USF Libraries
USF Digital Collections

Detailed geochemical and mineralogical analyses of naturally occurring arsenic in the Hawthorn Group

MISSING IMAGE

Material Information

Title:
Detailed geochemical and mineralogical analyses of naturally occurring arsenic in the Hawthorn Group
Physical Description:
Book
Language:
English
Creator:
Lazareva, Olesya
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla.
Publication Date:

Subjects

Subjects / Keywords:
phosphate
mining
pyrite
aquifer
trace metal
Florida
Dissertations, Academic -- Geology -- Masters -- USF
Genre:
government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
ABSTRACT: In order to understand the mineralogical association and distribution of arsenic (As) in the Hawthorn Group in central Florida, I examined in detail the chemical and mineralogical composition of 361 samples that were collected from 16 cores. Geochemical analyses were performed by hydride generation - atomic fluorescence spectrometry (HG-AFS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The identification of discrete minerals was aided by scanning electron microscopy (SEM) and chemical compositions were obtained by electron-probe microanalyses (EMPA). Arsenic concentrations for all Hawthorn samples vary from 0.1 to 69.0 ppm with a mean of 5.6 ppm. Average As concentrations for the individual units of the Hawthorn Group vary significantly from 9.0 ppm in the Peace River Formation to 3.0 ppm in the Tampa Member of the Arcadia Formation.This detailed mineralogical and geochemical study demonstrates that: (1) Arsenic in the Hawthorn Group varies from the formation to formation and is primarily concentrated in trace minerals, such as pyrite; (2) Concentrations of arsenic in pyrite crystals can vary drastically from a minimum of 0 ppm to a maximum of 8260 ppm; (3) Pyrite occurs in framboidal and euhedral forms and is unevenly distributed throughout the Hawthorn Group; (4) Hydrous ferric oxides can contain up to 540 ppm of arsenic; (5) Phosphate and organic material, and clays contain lower arsenic concentrations that pyrite and hydrous ferric oxides; and (6) Arsenic, sulfur, and iron have lognormal distribution throughout the Hawthorn Group. This study is important because phosphorous, arsenic and sulfur are chemically closely related, and thus they co-occur posing a potential problem for the phosphate industry.Information about the concentration, distribution and mineralogical association of naturally occurring arsenic is essential to forecast its behavior during anthropogenically induced physico-chemical changes in the aquifer. Recently, aquifer storage and recovery (ASR) facilities in west-central Florida reported arsenic concentrations in excess of 100 micro g/L (100 ppb) in recovered water. The ASR storage zone in this area is in the Suwannee Limestone, which directly underlies the Hawthorn sediments. It is crucial to the future of ASR in this area to understand the source, distribution, and cycling of arsenic in the overlying Hawthorn Group and the Florida Platform.
Thesis:
Thesis (M.S.)--University of South Florida, 2004.
Bibliography:
Includes bibliographical references.
System Details:
System requirements: World Wide Web browser and PDF reader.
System Details:
Mode of access: World Wide Web.
Statement of Responsibility:
by Olesya Lazareva.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 140 pages.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001498125
oclc - 57715404
notis - AJU6720
usfldc doi - E14-SFE0000521
usfldc handle - e14.521
System ID:
SFS0025212:00001


This item is only available as the following downloads:


Full Text

PAGE 1

D e t a i l e d G e o c h e m i c a l a n d M i n e r a l o g i c a l A n a l y s e s o f N a t u r a l l y O c c u r r i n g A r s e n i c i n t h e H a w t h o r n G r o u p b y O l e s y a L a z a r e v a A t h e s i s s u b m i t t e d i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r t h e d e g r e e o f M a s t e r o f S c i e n c e D e p a r t m e n t o f G e o l o g y C o l l e g e o f A r t s a n d S c i e n c e s U n i v e r s i t y o f S o u t h F l o r i d a M a j o r P r o f e s s o r : T h o m a s P i c h l e r P h D T h o m a s S c o t t P h D J o n a t h a n A r t h u r P h D P e t e r H a r r i e s P h D D a t e o f A p p r o v a l : N o v e m b e r 2 2 0 0 4 K e y w o r d s : p h o s p h a t e m i n i n g p y r i t e a q u i f e r t r a c e m e t a l f l o r i d a C o p y r i g h t 2 0 0 4 O l e s y a L a z a r e v a

PAGE 2

ACKNOWLEDGEMENTS First and foremost, I would like to gratefully acknowledge the help, support and encouragement of my advisor Dr. Thomas Pichler, who presented me with this wonderful opportunity, and assisted me with developing th e research topic and with completing and revising the paper. His contribution to my development as a geochemist cannot be underestimated. I am extremely thankful for his endless effort to provide invaluable assistance and inspired ideas. It was my luck to work with Dr. Thomas Pichler as my advisor. I would like greatly appreciate Southwes t Florida Water Management District (SWFWMD) and Mr. Greg Jones, Dir ector of Resource and Conservation Development for SWFWMD, for financial support of this project I would like to thank my Thesis Comm ittee, Dr. Thomas Scott, Dr. Jonathan Arthur, and Dr. Peter Harri es, for supporting me throughout my academic career, reviewing the manuscript a nd providing very valuable and helpful suggestions. I am also grateful to Dr. Chuck Connor Department of Geology Chair, for his support in my efforts to study statistics. I want to express my gratitude to a great colleague a nd a good friend, Roy Price, for his incredible help during fi eld work and throughout the entire academic period.

PAGE 3

I would like to thank faculty, staff and students in the Department of Geology, University of South Florida for their support and guidance throughout this work. Finally I am grateful to my famil y, my lovely boyfriend Dmitri Prokhorov, and his wonderful parents for their constant inspiration, advice, support, and wisdom. Without their help, patience, and love this work would never happen.

PAGE 4

i T A B L E O F C O N T E N T S L I S T O F T A B L E S i v L I S T O F F I G U R E S v A B S T R A C T v i i i C H A P T E R O N E : I N T R O D U C T I O N 1 P r o b l e m S t a t e m e n t 2 P u r p o s e o f R e s e a r c h 3 R e s e a r c h P l a n 4 C H A P T E R T W O : G E O L O G Y A N D H Y D R O G E O L O G Y 9 A r c a d i a F o r m a t i o n 1 1 T a m p a M e m b e r 1 1 N o c a t e e M e m b e r 1 3 P e a c e R i v e r F o r m a t i o n 1 3 O r i g i n o f F l o r i d a ’ s P h o s p h a t e D e p o s i t s 1 7 P o s s i b l e A r s e n i c i n t h e H a w t h o r n G r o u p 1 8 F r a n c o l i t e ( C a r b o n a t e F l u o r a p a t i t e ) 1 9 S u l f i d e M i n e r a l s 1 9 C l a y a n d O r g a n i c M a t e r i a l 2 0 H y d r o u s F e r r i c O x i d e s ( H F O ) 2 0 C H A P T E R T H R E E : M E T H O D S 2 2 S a m p l e C o l l e c t i o n a n d P r e p a r a t i o n 2 2 P e t r o g r a p h y a n d M i n e r a l o g y 2 3 S t e r e o a n d P e t r o g r a p h i c M i c r o s c o p y 2 3 S c a n n i n g E l e c t r o n M i c r o s c o p y 2 4 C h e m i s t r y 2 4 I n d u c t i v e l y C o u p l e d P l a s m a – O p t i c a l E m i s s i o n S p e c t r o m e t r y a n d H y d r i d e G e n e r a t i o n A t o m i c F l u o r e s c e n c e S p e c t r o m e t r y 2 4 E l e c t r o n P r o b e M i c r o a n a l y s e r – W a v e D i s p e r s i v e S p e c t r o m e t r y 2 6 S t a t i s t i c s 2 6 C H A P T E R F O U R : R E S U L T S 2 8 P e t r o g r a p h y a n d M i n e r a l o g y 2 8 S t e r e o a n d P e t r o g r a p h i c M i c r o s c o p y 2 8 A r c a d i a F o r m a t i o n 2 8

PAGE 5

i i P e a c e R i v e r F o r m a t i o n 3 0 S c a n n i n g E l e c t r o n M i c r o s c o p y 3 0 B u l k C h e m i c a l C o m p o s i t i o n 3 2 H a w t h o r n G r o u p ( A l l s a m p l e s ) 3 2 H a w t h o r n G r o u p ( I n t e r v a l S a m p l e s ) 3 5 U n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n 3 6 T a m p a M e m b e r 3 8 N o c a t e e M e m b e r 4 0 P e a c e R i v e r F o r m a t i o n 4 2 E l e c t r o n P r o b e M i c r o a n a l y s e r – W a v e D i s p e r s i v e S p e c t r o m e t r y 4 5 H a w t h o r n G r o u p ( A l l s a m p l e s ) 4 5 U n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n 4 6 T a m p a M e m b e r 4 9 N o c a t e e M e m b e r 4 9 P e a c e R i v e r F o r m a t i o n 5 0 P r o b a b i l i t y A n a l y s i s 5 3 C H A P T E R F I V E : D I S C U S S I O N 6 3 A b u n d a n c e o f A r s e n i c i n t h e H a w t h o r n G r o u p 6 3 S o u r c e s o f A r s e n i c i n t h e H a w t h o r n G r o u p 7 1 F r a n c o l i t e ( C a r b o n a t e F l u o r a p a t i t e ) 7 1 P y r i t e 7 2 C l a y a n d O r g a n i c M a t t e r 7 3 H y d r o u s F e r r i c O x i d e s ( H F O ) 7 4 Q u a n t i f i e d R o l e o f P y r i t e 7 4 M o b i l i z a t i o n o f A r s e n i c d u r i n g P h o s p h a t e M i n i n g 7 7 M o b i l i z a t i o n o f A r s e n i c d u r i n g A q u i f e r S t o r a g e a n d R e c o v e r y ( A S R ) 7 9 C H A P T E R F I V E : C O N C L U S I O N S 8 1 R E F E R E N C E S 8 3 A P P E N D I C E S 9 0 A P P E N D I X A : D e t a i l e d L i t h o l o g i c a l D e s c r i p t i o n s o f t h e A r c a d i a F o r m a t i o n C o r e S a m p l e s 9 1 A P P E N D I X B : D e t a i l e d L i t h o l o g i c a l C o m p o s i t i o n o f t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n C o r e S a m p l e s 9 7

PAGE 6

i i i A P P E N D I X C : D e t a i l e d L i t h o l o g i c a l C o m p o s i t i o n o f t h e N o c a t e e M e m b e r o f t h e A r c a d i a F o r m a t i o n C o r e S a m p l e s 1 0 0 A P P E N D I X D : D e t a i l e d L i t h o l o g i c a l D e s c r i p t i o n s o f t h e P e a c e R i v e r F o r m a t i o n C o r e S a m p l e s 1 0 2 A P P E N D I X E : I C P O E S R e s u l t s f o r t h e A r c a d i a F o r m a t i o n 1 0 5 A P P E N D I X F : I C P O E S R e s u l t s f o r t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n 1 1 3 A P P E N D I X G : I C P O E S R e s u l t s f o r t h e N o c a t e e M e m b e r o f t h e A r c a d i a F o r m a t i o n 1 1 7 A P P E N D I X H : I C P O E S R e s u l t s f o r t h e P e a c e R i v e r F o r m a t i o n 1 2 0 A P P E N D I X I : E l e c t r o n – P r o b e M i c r o a n a l y s i s o f P y r i t e s 1 2 2

PAGE 7

i v L I S T O F T A B L E S T a b l e 1 a L i s t o f 1 6 c o r e w e l l s c h o s e n f o r t h i s r e s e a r c h ( E n g l i s h u n i t s ) 7 T a b l e 1 b L i s t o f 1 6 c o r e s c h o s e n f o r t h i s s t u d y ( M e t r i c u n i t s ) 8 T a b l e 2 M a x i m u m M i n i m u m M e a n a n d S t a n d a r d D e v i a t i o n o f a r s e n i c c o n c e n t r a t i o n s i n p p m f o r t h e H a w t h o r n G r o u p a n d i t s F o r m a t i o n s / M e m b e r s 3 3 T a b l e 3 C o r r e l a t i o n m a t r i x f o r t h e H a w t h o r n G r o u p ( a l l s a m p l e s ) 3 5 T a b l e 4 C o r r e l a t i o n m a t r i x f o r t h e H a w t h o r n G r o u p ( i n t e r v a l s a m p l e s ) 3 6 T a b l e 5 C o r r e l a t i o n m a t r i x f o r t h e u n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n 3 8 T a b l e 6 C o r r e l a t i o n m a t r i x f o r t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n 3 9 T a b l e 7 C o r r e l a t i o n m a t r i x f o r t h e N o c a t e e M e m b e r o f t h e A r c a d i a F o r m a t i o n 4 2 T a b l e 8 C o r r e l a t i o n m a t r i x f o r t h e P e a c e R i v e r F o r m a t i o n 4 4 T a b l e 9 E l e c t r o n m i c r o p r o b e r e s u l t s f o r a r s e n i c i n p y r i t e s f o r t h e F o r m a t i o n / M e m b e r o f t h e H a w t h o r n G r o u p ( i n p p m ) 4 6 T a b l e 1 0 E l e c t r o n m i c r o p r o b e r e s u l t s f o r a r s e n i c i n p y r i t e s a n d p h o s p h a t e m a t r i x i n s a m p l e 5 1 2 3 5 f o r t h e u n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n ( w t % ) 4 8 T a b l e 1 1 E l e c t r o n m i c r o p r o b e r e s u l t s f o r a r s e n i c i n p y r i t e s a n d h y d r o u s f e r r i c o x i d e s i n s a m p l e 4 1 5 0 1 f o r t h e u n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n ( i n w e i g h t p e r c e n t ) 4 9 T a b l e 1 2 P r o b a b i l i t y o f a r s e n i c c o n c e n t r a t i o n s b e i n g l a r g e r t h a n c o r r e s p o n d i n g v a l u e s t h r o u g h o u t t h e H a w t h o r n G r o u p 6 2 T a b l e 1 3 M e a s u r e d b u l k a r s e n i c c o n c e n t r a t i o n s a n d c a l c u l a t e d a r s e n i c i n p y r i t e 7 5

PAGE 8

v L I S T O F F I G U R E S F i g u r e 1 M a p o f t h e r e s e a r c h a r e a i n c l u d i n g t h e R O M P l o c a t i o n s n u m b e r s n a m e s a n d t h e F G S w e l l n u m b e r s o f t h e 1 6 c o r e s t h a t w e r e s a m p l e d 5 F i g u r e 2 L i t h o s t r a t i g r a p h i c a n d h y d r o g e o l o g i c u n i t s o f t h e s t u d y a r e a 1 2 F i g u r e 3 G e o l o g i c a l c r o s s s e c t i o n s o f s o u t h w e s t e r n F l o r i d a 1 5 F i g u r e 4 G e o l o g i c a l c r o s s s e c t i o n s o f s o u t h w e s t e r n F l o r i d a H i l l s b o r o u g h a n d M a n a t e e C o u n t i e s 1 6 F i g u r e 5 B a c k s c a t t e r e d i m a g e s o f f r a m b o i d a l p y r i t e ( p y ) i n c a r b o n a t e m a t r i x ( c a r b ) f r o m s a m p l e 2 0 1 4 3 ( A r c a d i a F o r m a t i o n ) 2 9 F i g u r e 6 S c a n n i n g e l e c t r o n m i c r o g r a p h o f f r a m b o i d a l p y r i t e ( p y ) o n t o k a o l i n i t e ( k a o l ) i n s a m p l e 2 2 1 7 0 f r o m t h e T a m p a M e m b e r ( a r s e n i c c o n c e n t r a t i o n i s 1 4 0 p p m ) 3 1 F i g u r e 7 S c a n n i n g e l e c t r o n m i c r o g r a p h o f e u h e d r a l p y r i t e ( p y ) i n s a m p l e 4 1 5 9 9 f r o m t h e A r c a d i a F o r m a t i o n ( a r s e n i c c o n c e n t r a t i o n i s 7 5 p p m ) 3 1 F i g u r e 8 D i a g r a m s s h o w i n g c o r r e l a t i o n b e t w e e n F e a n d S i n t h e H a w t h o r n G r o u p a l l d a t a ( A ) a n d w i t h o u t t h e o u t l i e r ( B ) 3 4 F i g u r e 9 C o r r e l a t i o n b e t w e e n F e a n d S f o r t h e H a w t h o r n G r o u p i n t e r v a l s a m p l e s 3 5 F i g u r e 1 0 C o r r e l a t i o n b e t w e e n F e a n d S f o r t h e U n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n 3 7 F i g u r e 1 1 C o r r e l a t i o n b e t w e e n F e a n d S f o r t h e T a m p a M e m b e r 3 9 F i g u r e 1 2 C o r r e l a t i o n b e t w e e n A s a n d S f o r t h e T a m p a M e m b e r 4 0 F i g u r e 1 3 C o r r e l a t i o n b e t w e e n F e a n d S f o r t h e N o c a t e e M e m b e r 4 1 F i g u r e 1 4 D i a g r a m s s h o w i n g c o r r e l a t i o n b e t w e e n F e a n d S i n t h e P e a c e R i v e r F o r m a t i o n f o r a l l d a t a s e t ( A ) a n d w i t h r e m o v e d o u t l i e r ( B ) 4 4

PAGE 9

v i F i g u r e 1 5 E l e m e n t a l m a p p i n g o f p h o s p h o r i t e i n s a m p l e 5 1 2 3 5 ( A r c a d i a F o r m a t i o n ) 4 7 F i g u r e 1 6 ( A ) P h o t o g r a p h o f s a m p l e 4 1 5 0 1 ( u n d i f f e r e n t i a t e d A r c a d i a F o r m a t i o n ) ; ( B ) B a c k s c a t t e r e d i m a g e o f p y r i t e s ( p y ) h y d r o u s f e r r i c o x i d e s ( H F O ) a n d c a r b o n a t e m a t r i x ( c a r b ) 4 8 F i g u r e 1 7 ( A ) P h o t o g r a p h o f s a m p l e 1 2 – 1 2 5 ( P e a c e R i v e r F o r m a t i o n ) c o m p o s e d o f c l a y s ( 1 = 1 2 – 1 2 5 ( 1 ) ) a n d p y r i t e – p h o s p h a t e m a t r i x ( 2 = 1 2 1 2 5 ( 2 ) ) ; ( B ) P h o t o m i c r o g r a p h o f c o n t a c t b e t w e e n s a m p l e ( 1 ) a n d ( 2 ) ; ( C ) B a c k s c a t t e r e d i m a g e o f p y r i t e ( p y ) c l a y ( c l ) a n d p h o s p h a t e ( p h ) 5 1 F i g u r e 1 8 E l e m e n t a l m a p p i n g o f p y r i t e i n s a m p l e 1 2 1 2 5 ( P e a c e R i v e r F o r m a t i o n ) 5 2 F i g u r e 1 9 F r e q u e n c y h i s t o g r a m a n d n o r m a l P P p l o t o f l o g t r a n s f o r m e d a r s e n i c c o n c e n t r a t i o n s f r o m t h e H a w t h o r n G r o u p 5 3 F i g u r e 2 0 F r e q u e n c y h i s t o g r a m a n d n o r m a l P P p l o t o f l o g t r a n s f o r m e d s u l f u r c o n c e n t r a t i o n s f r o m t h e H a w t h o r n G r o u p 5 4 F i g u r e 2 1 F r e q u e n c y h i s t o g r a m a n d n o r m a l P P p l o t o f l o g t r a n s f o r m e d i r o n c o n c e n t r a t i o n s f r o m t h e H a w t h o r n G r o u p 5 4 F i g u r e 2 2 C u m u l a t i v e d i s t r i b u t i o n f u n c t i o n o f l o g t r a n s f o r m e d a r s e n i c c o n c e n t r a t i o n s f o r t h e a l l H a w t h o r n G r o u p 5 5 F i g u r e 2 3 F r e q u e n c y h i s t o g r a m a n d n o r m a l P P p l o t o f l o g t r a n s f o r m e d a r s e n i c c o n c e n t r a t i o n s f r o m t h e H a w t h o r n G r o u p i n t e r v a l s a m p l e s 5 6 F i g u r e 2 4 C u m u l a t i v e d i s t r i b u t i o n f u n c t i o n o f l o g t r a n s f o r m e d a r s e n i c c o n c e n t r a t i o n s f o r t h e i n t e r v a l H a w t h o r n s a m p l e s 5 6 F i g u r e 2 5 S u r v i v o r p r o b a b i l i t y f u n c t i o n s o f l o g t r a n s f o r m e d ( A ) a n d a c t u a l ( B ) a r s e n i c c o n c e n t r a t i o n s f o r t h e A r c a d i a F o r m a t i o n 5 8 F i g u r e 2 6 S u r v i v o r p r o b a b i l i t y f u n c t i o n s o f l o g t r a n s f o r m e d ( A ) a n d a c t u a l ( B ) a r s e n i c c o n c e n t r a t i o n s f o r t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n 5 9 F i g u r e 2 7 S u r v i v o r p r o b a b i l i t y f u n c t i o n s o f l o g t r a n s f o r m e d ( A ) a n d a c t u a l ( B ) a r s e n i c c o n c e n t r a t i o n s f o r t h e N o c a t e e M e m b e r o f t h e A r c a d i a F o r m a t i o n 6 0

PAGE 10

v i i F i g u r e 2 8 S u r v i v o r p r o b a b i l i t y f u n c t i o n s o f l o g t r a n s f o r m e d ( A ) a n d a c t u a l ( B ) a r s e n i c c o n c e n t r a t i o n s f o r t h e P e a c e R i v e r F o r m a t i o n 6 1 F i g u r e 2 9 D i a g r a m s h o w i n g t h e p r o b a b i l i t y o f a r s e n i c d i s t r i b u t i o n t h r o u g h o u t t h e H a w t h o r n G r o u p 6 2 F i g u r e 3 0 D i s t r i b u t i o n o f t h e m e a n a r s e n i c c o n c e n t r a t i o n s t h r o u g h o u t t h e H a w t h o r n G r o u p a l l d a t a ( A ) a n d w i t h o u t t h e o u t l i e r ( B ) 6 5 F i g u r e 3 1 D i s t r i b u t i o n o f t h e m e a n S F e A l a n d P c o n c e n t r a t i o n s t h r o u g h o u t t h e H a w t h o r n G r o u p 6 5 F i g u r e 3 2 S p a t i a l d i s t r i b u t i o n o f t h e m e a n c o n c e n t r a t i o n s ( i n p p m ) i n t h e H a w t h o r n G r o u p a l l d a t a ; s i z e o f p o i n t i n d i c a t e s r e l a t i v e m e a n o f a r s e n i c c o n c e n t r a t i o n 6 6 F i g u r e 3 3 S p a t i a l d i s t r i b u t i o n o f t h e m e a n c o n c e n t r a t i o n s ( i n p p m ) i n t h e A r c a d i a F o r m a t i o n ; s i z e o f p o i n t i n d i c a t e s r e l a t i v e m e a n o f a r s e n i c C o n c e n t r a t i o n 6 7 F i g u r e 3 4 S p a t i a l d i s t r i b u t i o n o f t h e m e a n c o n c e n t r a t i o n s ( i n p p m ) i n t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n ; s i z e o f p o i n t i n d i c a t e s r e l a t i v e m e a n o f a r s e n i c c o n c e n t r a t i o n 6 8 F i g u r e 3 5 S p a t i a l d i s t r i b u t i o n o f t h e m e a n c o n c e n t r a t i o n s ( i n p p m ) i n t h e N o c a t e e M e m b e r o f t h e A r c a d i a F o r m a t i o n ; s i z e o f p o i n t i n d i c a t e s r e l a t i v e m e a n o f a r s e n i c c o n c e n t r a t i o n 6 9 F i g u r e 3 6 S p a t i a l d i s t r i b u t i o n o f t h e m e a n c o n c e n t r a t i o n s ( i n p p m ) i n t h e P e a c e R i v e r F o r m a t i o n ; s i z e o f p o i n t i n d i c a t e s r e l a t i v e m e a n o f a r s e n i c c o n c e n t r a t i o n 7 0 F i g u r e 3 7 D i a g r a m s h o w i n g a r s e n i c c a l c u l a t e d v s a r s e n i c m e a s u r e d i n p y r i t e s f r o m t h e H a w t h o r n G r o u p i n c l u d i n g a l l d a t a ( A ) a n d e x c l u d i n g p o i n t s f r o m t h e c i r c l e ( B ) 7 7 F i g u r e 3 8 S t a b i l i t y d i a g r a m o f p y r i t e a n d F e ( O H ) 3 i n w a t e r a t 2 5 0 C a n d 1 a t m o s p h e r e t o t a l p r e s s u r e 8 0

PAGE 11

v i i i D e t a i l e d G e o c h e m i c a l a n d M i n e r a l o g i c a l A n a l y s e s o f N a t u r a l l y O c c u r r i n g A r s e n i c i n t h e H a w t h o r n G r o u p O l e s y a L a z a r e v a A B S T R A C T I n o r d e r t o u n d e r s t a n d t h e m i n e r a l o g i c a l a s s o c i a t i o n a n d d i s t r i b u t i o n o f a r s e n i c ( A s ) i n t h e H a w t h o r n G r o u p i n c e n t r a l F l o r i d a I e x a m i n e d i n d e t a i l t h e c h e m i c a l a n d m i n e r a l o g i c a l c o m p o s i t i o n o f 3 6 1 s a m p l e s t h a t w e r e c o l l e c t e d f r o m 1 6 c o r e s G e o c h e m i c a l a n a l y s e s w e r e p e r f o r m e d b y h y d r i d e g e n e r a t i o n a t o m i c f l u o r e s c e n c e s p e c t r o m e t r y ( H G A F S ) a n d i n d u c t i v e l y c o u p l e d p l a s m a o p t i c a l e m i s s i o n s p e c t r o m e t r y ( I C P O E S ) T h e i d e n t i f i c a t i o n o f d i s c r e t e m i n e r a l s w a s a i d e d b y s c a n n i n g e l e c t r o n m i c r o s c o p y ( S E M ) a n d c h e m i c a l c o m p o s i t i o n s w e r e o b t a i n e d b y e l e c t r o n p r o b e m i c r o a n a l y s e s ( E M P A ) A r s e n i c c o n c e n t r a t i o n s f o r a l l H a w t h o r n s a m p l e s v a r y f r o m 0 1 t o 6 9 0 p p m w i t h a m e a n o f 5 6 p p m A v e r a g e A s c o n c e n t r a t i o n s f o r t h e i n d i v i d u a l u n i t s o f t h e H a w t h o r n G r o u p v a r y s i g n i f i c a n t l y f r o m 9 0 p p m i n t h e P e a c e R i v e r F o r m a t i o n t o 3 0 p p m i n t h e T a m p a M e m b e r o f t h e A r c a d i a F o r m a t i o n T h i s d e t a i l e d m i n e r a l o g i c a l a n d g e o c h e m i c a l s t u d y d e m o n s t r a t e s t h a t : ( 1 ) A r s e n i c i n t h e H a w t h o r n G r o u p v a r i e s f r o m t h e f o r m a t i o n t o f o r m a t i o n a n d i s p r i m a r i l y c o n c e n t r a t e d i n t r a c e m i n e r a l s s u c h a s p y r i t e ; ( 2 ) C o n c e n t r a t i o n s o f a r s e n i c i n p y r i t e c r y s t a l s c a n v a r y d r a s t i c a l l y f r o m a

PAGE 12

i x m i n i m u m o f 0 p p m t o a m a x i m u m o f 8 2 6 0 p p m ; ( 3 ) P y r i t e o c c u r s i n f r a m b o i d a l a n d e u h e d r a l f o r m s a n d i s u n e v e n l y d i s t r i b u t e d t h r o u g h o u t t h e H a w t h o r n G r o u p ; ( 4 ) H y d r o u s f e r r i c o x i d e s c a n c o n t a i n u p t o 5 4 0 p p m o f a r s e n i c ; ( 5 ) P h o s p h a t e a n d o r g a n i c m a t e r i a l a n d c l a y s c o n t a i n l o w e r a r s e n i c c o n c e n t r a t i o n s t h a t p y r i t e a n d h y d r o u s f e r r i c o x i d e s ; a n d ( 6 ) A r s e n i c s u l f u r a n d i r o n h a v e l o g n o r m a l d i s t r i b u t i o n t h r o u g h o u t t h e H a w t h o r n G r o u p T h i s s t u d y i s i m p o r t a n t b e c a u s e p h o s p h o r o u s a r s e n i c a n d s u l f u r a r e c h e m i c a l l y c l o s e l y r e l a t e d a n d t h u s t h e y c o o c c u r p o s i n g a p o t e n t i a l p r o b l e m f o r t h e p h o s p h a t e i n d u s t r y I n f o r m a t i o n a b o u t t h e c o n c e n t r a t i o n d i s t r i b u t i o n a n d m i n e r a l o g i c a l a s s o c i a t i o n o f n a t u r a l l y o c c u r r i n g a r s e n i c i s e s s e n t i a l t o f o r e c a s t i t s b e h a v i o r d u r i n g a n t h r o p o g e n i c a l l y i n d u c e d p h y s i c o c h e m i c a l c h a n g e s i n t h e a q u i f e r R e c e n t l y a q u i f e r s t o r a g e a n d r e c o v e r y ( A S R ) f a c i l i t i e s i n w e s t c e n t r a l F l o r i d a r e p o r t e d a r s e n i c c o n c e n t r a t i o n s i n e x c e s s o f 1 0 0 g / L ( 1 0 0 p p b ) i n r e c o v e r e d w a t e r T h e A S R s t o r a g e z o n e i n t h i s a r e a i s i n t h e S u w a n n e e L i m e s t o n e w h i c h d i r e c t l y u n d e r l i e s t h e H a w t h o r n s e d i m e n t s I t i s c r u c i a l t o t h e f u t u r e o f A S R i n t h i s a r e a t o u n d e r s t a n d t h e s o u r c e d i s t r i b u t i o n a n d c y c l i n g o f a r s e n i c i n t h e o v e r l y i n g H a w t h o r n G r o u p a n d t h e F l o r i d a P l a t f o r m

PAGE 13

1 CHAPTER ONE INTRODUCTION The first discovery of phosphate rock in Florida was opened in 1879 near Hawthorne, Alachua County by Dr. C.A. Simmons (Blakey, 1973), who instigated mining operations there in 1883. The origin al find was a low-grade, phosphatic limestone, possibly from the Hawthorn Group. At the present time, Florida phosphate mining of the Hawthorn Group supplies about one-quarter of the world's and threequarters of United States domestic phosphate needs. Most phosphate is used to produce feed supplements, soft drinks, vitami ns, toothpaste and as fertilizers. In 2000, $1.13 billion dollars of fertilizer were sold overseas from the state of Florida (Hodges et al., 2001). In addition to the phosphate mining indus try there are several aquifer storage and recovery (ASR) facilities in Florida. Aquifer storage and recovery is the procedure of storing treated recharge water in a confined aquifer during rainy seasons with the subsequent recovery of that water during dry seasons. ASR is rapidly developing into substitute choice to wit hdrawing Florida aquifer groundwater due to growing water demands in highly populated areas of the Florida peninsula (Jones and Owen, 2001).

PAGE 14

2 Problem Statement The Environmental Protection Agency (EPA) approved a new standard for arsenic in drinking water of 10 g/L beginning January 23, 2006 (www.epa.gov/safewater/arseni c.html). Recently, aquife r storage and recovery (ASR) facilities in cen tral Florida reported arsenic concentrations in excess of 100 g/L (100 ppb) in recovered water (Arthur et al., 2001; Arthur et al., 2002). The ASR storage zone in the study area is the Su wannee Limestone, which directly underlies the Hawthorn sediments. The ASR storage z ones in other parts of Florida are the Avon Park Formation, Ocala Group, and a pa rt of the Hawthorn Group. The arsenic in the Suwannee Limestone storage zone may have migrated from the Hawthorn Group (Price and Pichler, 2002). Therefore, information about its concentration, distribution, and mineralogical a ssociation is important, becaus e this is a first step to forecast its behavior during anthropogenica lly induced physico-chemical changes in the aquifer. Because phosphorous, arsenic and sulfur are chemically closely related, they co-occur in nature. In add ition, the highly open crystal structure of francolite (carbonate fluorapatite) shows a tendency to accumulate such elements as As, Mo, Se, Y, Zn, and the REE during diagenesis which poses a potential problem for the phosphate industry. There have been several occurrences of swine fatalities due to arsenic poisoning as a result of phosphate feed supplements (El Bahri et al., 1991).

PAGE 15

3 The study area is located in the Southwes t Florida Water Management District (SWFWMD) between Tampa and Fort My ers. The research area includes both, phosphate mining facilities and aquifer st orage and recovery (ASR) projects. Purpose of Research This research was funded by the Southwest Florida Water Management District (SWFWMD) to determine the geogr aphic and stratigraphic distribution of arsenic in the Hawthorn Group and to provi de new information about the fate and cycling of arsenic throughout the Florida platform. Therefore, the six main questions to be answered in this research are: What is the concentration of arsenic in the Hawthorn Group? How does concentration of arsenic vary from the Formation to Formation and from the Member to Member of the Hawthorn Group? What are the mineralogical associatio ns and distribution of arsenic in the Hawthorn Group? What are the potential arsenic contamination problems for the phosphate mining industry? What is the predicted behavior of the arsenic in the Hawthorn Group during ASR? What is the spatial distribution of arsenic in the Hawthorn units?

PAGE 16

4 Research Plan A combination of petrographic and ge ochemical techniques was applied to evaluate the abundance and mine ralogical associations of ar senic in 16 cores from the Hawthorn Group (Table 1a, 1b and Figure 1). The cores were in itially collected as part of the Regional Observation Monitor We ll Program (ROMP) by the SWFWMD. The cores were chosen on the basis of their pr oximity to the Central Florida Phosphate District. In addition, core selection was based on a previous study (Price, 2003) detailing the abundance and mineralogical association of arsenic in the Suwannee Limestone, which directly underlies the Hawthorn Group sediments. The cores are archived at the warehouse of the Florida Ge ological Survey (FGS) in Tallahassee and were accessible for sampling. Each core wa s sampled at evenly spaced distance to represent the entire Hawthorn Group interval. In addition, samples with possibly high arsenic concentrations were taken, where trace minerals, organic matter, or minor constituents were visible. The samples were examined and described in detail using stereo microscopy, and polished thin sections of selected samples were studied using petrographic microscope for mineralogical determinations. Additionally, several samples were selected for a more focused mineral ogical analysis usi ng scanning electron microscopy (SEM). To perform a bulk chemical composition of the Hawthorn Group samples, the following chemical elements were analy zed by inductively coupled plasma optical emission spectroscopy (ICP-OES): calcium (Ca), iron (Fe), magnesium (Mg),

PAGE 17

5 Figure 1. Map of the research area includi ng the ROMP locations, numbers, names, and the FGS well numbers of the 16 cores that were sampled.

PAGE 18

6 manganese (Mn), sulfur (S), phosphorous (P ), silica (Si), and aluminum (Al). Bulk arsenic (As) concentrations were de termined by hydride generation-atomic fluorescence spectrometry (HG-AFS) at the Ce nter for Water Analysis, University of South Florida. These chemical elements we re selected to determine mineralogical composition of the Hawthorn Group and to asse ss possible correlations with arsenic. To better understand the mineral phases containing arsenic, several samples with high arsenic concentrations were se lected for electron-probe microanalysis (EMPA) at the University of New Mexico.

PAGE 19

Table.1a. List of 16 core wells chosen for this research (English units). County ROMP Number ROMP Name FGS well id Hawthorn Interval (ft) Monitor -top (ft bsl) Monitorbot (ft bsl) Total (ft bsl) Surface Elevation (ft bsl) DESOTO 13 Tippen Bay 17392 19-704 282 592 310 61.5 DESOTO 17 Horse Creek 15303 26-439 100 470 370 22.6 DESOTO 12 Prairie Creek 16578 40-719 280 710 430 41.0 HILLSBOROUGH 49 Balm 16456 78-379 195 620 425 151.1 HILLSBOROUGH DV-1 DV-1 16576 ?-153 90 139 49 112.5 HILLSBOROUGH TR 9-2 Apollo Beach 16618 36-268 118 148 30 10.6 MANATEE 39 Oak Knoll 16740 47-513 125 207 82 125.0 CHARLOTTE TR 3-3 Lemon Bay 15683 56-686 155 410 255 5.8 CHARLOTTE 5 Cecil Webb 16913 69-711 130 600 470 40.1 SARASOTA 9 North Port 17056 27.5-545 40 320 280 25.0 SARASOTA 20 Osprey 17087 38.5-479 75 370 295 18.4 SARASOTA TR 5-1 Laurel 15168 86-488 275 289 14 11.6 SARASOTA 22 Utopia 16783 18.6-373.5 95 290 195 34.5 SARASOTA TR SA-1 Payne Terminal 17452 29-484 328 388 60 6.5 SARASOTA TR 4-1 Casperson Beach 17488 26-599 30 645 615 10.0 HARDEE 25 Lily 17608 45-313 105 145 40 85 7

PAGE 20

Table 1b. List of 16 cores chosen for this study (Metric units). County ROMP Number ROMP Name FGS well id Hawthorn Interval (m) Monitor -top (m bsl) Monitor -bot (m bsl) Total (m bsl) Surface Elevation (m bsl) DESOTO 13 Tippen Bay 17392 6-215 86 180 94 19 DESOTO 17 Horse Creek 15303 8-134 30 143 113 7 DESOTO 12 Prairie Creek 16578 12-219 85 216 131 12 HILLSBOROUGH 49 Balm 16456 24-116 59 189 130 46 HILLSBOROUGH DV-1 DV-1 16576 2-47 27 42 15 34 HILLSBOROUGH TR 9-2 Apollo Beach 16618 11-82 36 45 9 3 MANATEE 39 Oak Knoll 16740 14-156 38 63 25 38 CHARLOTTE TR 3-3 Lemon Bay 15683 17-209 47 125 78 2 CHARLOTTE 5 Cecil Webb 16913 21-217 40 183 143 12 SARASOTA 9 North Port 17056 8-166 12 98 85 8 SARASOTA 20 Osprey 17087 12-146 23 113 90 6 SARASOTA TR 5-1 Laurel 15168 26-149 84 88 4 4 SARASOTA 22 Utopia 16783 6-114 29 88 59 11 SARASOTA TR SA-1 Payne Terminal 17452 9-148 100 118 18 2 SARASOTA TR 4-1 Casperson Beach 17488 8-183 9 197 187 3 HARDEE 25 Lily 17608 14-95 32 44 12 26 8

PAGE 21

9 CHAPTER TWO GEOLOGY AND HYDROGEOLOGY The stratigraphic unit for this study is the predominantly Miocene Hawthorn Group, which is subdivided into a lower section comprising the undifferentiated Arcadia Formation, Tampa and Nocatee Members of the Arcadia Formation and the upper section of the Peace River Formation (Scott, 1988). The hydrogeologic framework of the s outhwestern part of Florida is composed of three discrete hydrogeologi c units (Figure 2). The hydrogeologic units and their stratigraphic components include th e Floridan aquifer system (FAS), the Intermediate aquifer system (IAS) or Inte rmediate confining unit, and the Surficial aquifer system (SAS) (Figure 2). The Upper Pliocene to Pleistocene Surfic ial aquifer system (SAS) is generally comprised of unconsolidated to poorly indurat ed clastic deposits such as sands, sandy clays, phosphorite and some well-indurated carbonate rocks (Fi gure 2). The SAS is primarily unconfined with some semi-confin ed or locally confined sections (Gilboy, 1985). The Upper Oligocene to Lower Pliocene Intermediate aquifer system (IAS) consists of layers of clays, sand beds, carbonate lenses, and phosphorite (Figure 2). The water-yielding beds of car bonate lenses lie between cl ayey confining units. As a

PAGE 22

10 result, the water in the IAS is under prin cipally confined conditions excluding local areas, where the upper confining unit is missi ng and the system is in direct hydraulic contact with the overlying SAS. Generall y, water moves downward from the SAS and through the upper confining un it of the IAS and the majority of this water subsequently follows short flow paths and di scharges to surface drainage area. On the other hand, some water penetrates downward through the lower c onfining unit of the IAS to recharge the underlying FAS (USGS, 1999). The IAS is the major source of wate r supply in Charlotte and Sarasota Counties, where the underlyi ng FAS is deeply buried a nd holds only brackish or saltwater (SWFWMD, 2000). The FAS is a continuous sequence of carbonate rocks with generally high porosity and permeability. The confining unit separating the Upper and Lower Floridan aquifers consists of clay, dolomite with the pore spaces filled with anhydrite, or a very fine-grained (micritic) limestone (USGS, 1999). The FAS underlies a region of approximately 259,000 km2 throughout southern Alabama, southeastern Georgia, southern South Carolina, and the entire Florida peninsula; it is one of the most pr olific and extensive a quifers in the world. The Paleocene to Lower Miocene Floridan aquifer system (FAS) consists of the following stratigraphic uni ts (from oldest to youngest): The Oldsmar, Cedar Keys, and Avon Park Formations, and the Ocala and Suwannee Limestones (Figure 3). The Tampa Member and the lower part of th e Arcadia Formation of the Hawthorn Group

PAGE 23

11 are included in the upper part of the FA S where it comprises permeable carbonate lenses (Scott, 1991). Arcadia Formation The Arcadia Formation unconformabl y overlies the Oligocene Suwannee Limestone and achieves its maximum th ickness of about 183 m (600 ft) in the Okeechobee Basin (Scott, 1988). It was initia lly interpreted to be primarily Lower Miocene (Scott, 1988), but is now recogni zed to be Lower Oligocene to Middle Miocene (Brewster-Wingard et al., 1997; Missimer, 1997). The Arcadia Formation is comprised of the undifferentiated Arcadia Formation, the Tampa Member and the Nocatee Member (Figure 2). Throughout the research area the undi fferentiated Arcadia Formation is principally composed of variable amount of siliciclastics with in carbonate matrix (Figures 3, 4). The carbonates of the Arcad ia Formation are typically composed of fossiliferous, yellowish gray to light greenis h gray to light brown, microto finely crystalline limestones and dolostones with va riable amounts of quartz sands, gray to greenish gray clays, chert and phosphatic material (Scott, 1990). The clays are palygorskite, sepiolite illite/smectite mixed layer, and insignificant amounts of kaolinite (Compton et al., 1993). Thin beds of sand and clay are widespread and molds and casts of mollusks are commonly found in the dolostones.

PAGE 24

12 Figure 2. Lithostratigraphic and hydr ogeologic units of the study area (Modified from SWFWMD Report, 2000; Scott, 1989).

PAGE 25

13 Tampa Member The lithology of the Upper Oligocene to Lower Miocene Tampa Member of the Arcadia Formation (Figures 3, 4) vari es from a white to yellow-gray marine wackestone to packestone containing va riable amounts of dolostone, clay, quartz sand, and minor occurrences of phosphate material (Wingard et al., 1993; Scott, 1988). Thin carbonate, quartz sand and clay beds are commonly observed throughout the Tampa Member. The Tampa Member is typically a poor to well indurated limestone and in some areas it contains va riable amounts of fossils such as mollusks, corals, and foraminifera (Scott, 1988). Th e Tampa Member usually has intergranular or moldic porosity. The contact between the undifferentiated Arcadia Formation and Tampa Member in central Florida is sporadic ally marked by a chert layer at the top of the Tampa Member (Gilboy, 1985). Nocatee Member The Nocatee Member forms the base of the Arcadia Formation (Figure 2) in the southern area of SWFWMD. The study of Scott (1988) showed that the Upper Oligocene to Lower Miocene Nocatee Member of the Arcadia Formation contains the highest amount of siliciclas tic material compared to the entire Arcadia Formation.

PAGE 26

14 Peace River Formation The Peace River Formation unconformable overlies the Arcadia Formation and reaches a maximum thickness of 198 m (650 ft) in the Okeechobee Basin (Scott, 1990). The lithological composition of the Middle Miocene to Lower Pliocene (Missimer et al., 1994) Peace River Formation consists of gray to greenish gray clays (palygorskite, sepiolite, illite /smectite mixed layer), sandy clays, and carbonates with variable amounts of phosphate sand and grav el (Green at al., 1995). The carbonates are comprised of dolosilts, dolostones, and interbedded limestones (Figures 3, 4). The siliciclastic component is dominant th roughout the Peace River Formation (Scott, 1988). The Peace River Formation contains substantial amounts of phosphate material and is curr ently being exploited.

PAGE 27

Figure 3. Geological cross sections of southwestern Florida ( Modified from Gilboy, 1985 ). 15

PAGE 28

16 Figure 4. Geological cross sections of southwestern Florida Hillsborough and Manatee Counties ( Modified from Green et al., 1995 ).

PAGE 29

17 Origin of Florida’s Phosphorite Deposits Changes in global climate and sea leve l during the Miocene were associated with the development of widespread phos phorite deposits of the Hawthorn Group in Florida (Riggs, 1979, 1984; Compton et al., 1993). Phosphorite sediments in Florida consist of the carbonate fl uorapatite mineral francoli te. Other phosphorous-bearing minerals, such as crandallite and wavell ite, are a weathering product of francolite (Compton et al., 1993). These phosphorite sedi ments occur as sandto pebblesized peloidal grains that show no internal stru cture and are composed of black, brown or gray massive or cryptocrystalline francoli te. Other types of phosphorite particles are skeletal grains (teeth and bones) and molds of mollusks (Compton et al., 1993). The precipitation of phosphorite in th e Hawthorn Group is related to the upwelling of deep phosphorite-rich ocean wa ters along the continental margin during periods of high or rising sea level (Kazakov, 1937). The upwelling of deep cold water to shallow warmer regions caused the in crease of the surface productivity that contributed organic matter to sediment s (Compton et al., 1993). Degradation of organic substance in the sediment by bact erial activity caused the releasing of phosphorus to the pore water and eventual precipitation of pore-filling francolite. Hydrogen sulfide (H2S) that formed during sulfat e reduction under anoxic conditions resulted in the deposition of pyrite and dolomite rhombs or caused diffusion of H2S to bacterial mats with the subsequent oxidation back to sulfate. The inclusions of pyrite in the fibrous clay material (palygorskite and sepiolite) and numerous phosphorite

PAGE 30

18 grains indicate the same diagenetic envi ronment within the sulfate-reduction zone (Compton et al., 1993). Reworking of the Hawthorn sediment occurred during periods of marine regressions or low sea level. Alterati on of the deposits concentrated phosphorite grains and incorporated dolomite rhombs in to dolomite beds and dolosilt layers. In the same time much of the organic substa nce and pyrite were altered by oxidation. Possible Sources of Arsenic in the Hawthorn Group Generally, there are four major possibl e sources of arsenic in the Hawthorn Group: Francolite (Carbonate Fluorapatite); Sulfide minerals such as pyrite and arsenopyrite; Clay and organic matter; Hydrous ferric oxides (HFO). Hinkle and Polette (1999) re ported two principal proce sses that mainly control arsenic mobility in aquifers: (1) adso rption and desorption and (2) solid-phase precipitation and dissolution reactions. Arse nic adsorption and desorption reactions are influenced by changes in pH, red ox (reduction/oxidation) reactions and the presence of competing anions. Solid-phase precipitation and dissolution reactions are primarily controlled by pH, redox state a nd chemical composition (saturation).

PAGE 31

19 Francolite (Carbonate Fluorapatite) Francolite chemistry is extremely co mplex, but its chemical composition can be given as a general formula: Ca10-a-b NaaMgb (PO4) 6-x (CO3) x-y-z (CO3.F) y (SO4) zF2p OHp. The highly open crystal structure of fr ancolite permits substantial substitution at any of the fluorap atite sites, e.g. Na+, Mg2+, Sr2+ for Ca2+; OH-, AsO 3CrO 2-, VO 3for PO 3-; and Cl-, Brfor F (Shields, 2002). A tendency to accumulate elements, such as As, Mo, Se, Y, Zn, and the REE during diagenesis is a poorly understood characteristic of francolite (Shields, 2002). According to Smedley and Kinniburgh (2003) calcium phosphate or apatite can contain up to 1000 mg/kg of arsenic. On the other hand, Stow (1969) did not reveal any correlation between arsenic and phosphorous in the Bone Valley Member of the Hawthorn Group. Sulfide Minerals (Pyrite) Prior studies of sulfide minerals su ch as the abundance and occurrence of pyrite in the Suwannee Limestone (Price a nd Pichler, 2004, in re view; Price, 2003; Price and Pichler, 2002) revealed significan t enrichment of arse nic in pyrite with concentrations as high as 11,200 ppm. Thom as and Sanders (1998) reported arsenic concentrations in pyrite framboids of up to 1000 ppm as a substitute element for sulfur in the FeS2 structure. Huerta-Diaz and Morse (1990) found arsenic

PAGE 32

20 concentrations in marine sedimentary pyrit es of as much as 0.93 wt. %. Therefore, sedimentary pyrite can be a signif icant sink and source of arsenic. Clay and Organic Matter It has been reported that soil consti tuents, such as clays and organic substances, can easily interact with heavy metals such as arsenic via ion exchange or surface adsorption (Manning, Goldberg, 1997; Evangelou, 1995). Clays readily adsorb arsenic because of the oxide-like char acter of the edges of its grains (Claesson et al., 2003). Clays and organic substance have very small particle size, which therefore result in a large su rface area per unit volume and ab ility to adsorb arsenic. Moreover, the potential of hu mic substances to complex with heavy metals is due to the existence of oxygen-containing func tional groups such as carboxyl (COOH), hydroxyl (Oh), and carbonyl (C=O) (Evangelou, 1995). Hydrous Ferric Oxides (HFO) Reworking of the Hawthorn Group sedi ment during periods of marine regressions caused oxidation of some pyrite and forma tion of iron oxyhydroxides or hydrous ferric oxides (HFO) (Compton et al., 1993). It has been shown that arsenic integrates into sediments by co-precipitati on as hydrous ferric oxides (HFO), or is adsorbed onto extremely high surface area of precipitated HFO (Hongshao and Stanforth, 2001; Hinkle et al., 1999; Evangelou, 1995). High concentrations of arsenic are found in HFO (Bowell, 1994; Cha o, Theobald, 1976). It has been reported

PAGE 33

21 the close connection between hydrous ferric ox ides and arsenic (Pichler et al., 2000; Chao, Theobald, 1976). Stow (1969) concludes that most of the arsenic in the Bone Valley Member of the Hawthorn Group is adsorbed on HFO. Nickson et al. (2000) found high arse nic in the groundwater of Bangladesh that had been derived from reductive dissolu tion of arsenic-rich hydrous ferric oxides that exists as a coating on sedimentary grains.

PAGE 34

22 CHAPTER THREE METHODS Sample Collection and Preparation The present study addresse s the detailed mineralo gy and geochemistry of arsenic in the Miocene Hawt horn Group. In order to conduct the research, 55 samples from the Peace River Formation, 205 samples from the Arcadia Formation, 75 samples from the Tampa Member, and 27 samples from the Nocatee Member of the Hawthorn Group were collected and analyzed from the 16 ROMP wells (Figure 1). During sampling, each core was taken at an even distance to demonstrate the entire Hawthorn Group interval. Samples at intervals of 7.6 m (25f t) and samples of special interest were obtained. Samples of in terest were taken from sections likely to have high arsenic concentrations such as areas with pyrite crys tals, hydrous ferric oxides, green clays, and organic material. Sa mples were sealed and labeled in plastic bags and brought back from the Florida Geological Survey in Tallahassee to the University of South Florida. The sediment samples were powdered in an agate mortar and stored in plastic vials. The cross-c ontamination between samples was minimized by cleaning mortar and pestle with pure silica sand and deioni sed water (DI) of 17.9 m and with nitric acid (1:1 HNO3) if softy greenish clays were present.

PAGE 35

23 Approximately 0.5 g 0.001 g of dried, powdered, homogenous sample was weighted into a digestion vessel and 10 mL of a 3:1 mixture of hydrochloric (HCl) and nitric acid (3HNO) was added. The digestion vessel was immediately capped with a reflux cup to avoid the escape of arsine gas. The sample was heated to a temperature of 950C for 30 minutes. After digesti on, the solution was cooled down, diluted to 50 mL (5:1) with DI water, centrifuged for 15 minutes to remove nonsoluble particles, and filtered. Mineralogy and Petrography Stereo and Petrographic Microscopy Hand samples were examined and lithol ogically described in the field and laboratory using a 10x hand lens and a SZ -PT Olympus stereo microscope with FostecR 150 watt tungsten halogen light source. When high arsenic concentrations were determined by chemical analyses (expl ained below), the stereo microscope was used again for a more detailed study. Approximately 60 thin sections of se lected samples were made to get a detailed mineralogical composition of the Hawthorn Group. Thin sections have been made as polished sections with blue dye impregnation and were described using a Meiji Techno ML 9400 polarizing microscope with reflected and transmitted light. Subsequently, about 18 thin sections were selected for the EMPA to study chemical composition of individual minerals (explained below).

PAGE 36

24 Scanning Electron Microscopy Based on geochemical data, several samp les with high arsenic levels were selected for a more focused mineral ogical analysis usi ng scanning electron microscopy (SEM). The Hitachi S-3500N variable pressure scanning electron microscope is located at the College of Mari ne Science, University of South Florida. The SEM is equipped with a Robinson Backscattered de tector for atomic number contrast. This type of analysis consists of mounting small sample chips onto an aluminum stub. The sample was sputter coat ed with Au/Pd coating (for imaging). Chemistry Inductively Coupled Argon Plasma Op tical Emission Spectroscopy and Hydride Generation Atomic Fluorescence Spectrometry To determine the concentration of ar senic (As), calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), sulfur (S), phosphorous (P), silica (Si) and aluminum (Al) of the Hawthorn Group, samp les were analyzed by a combination of Inductively Coupled Argon Plasma Opti cal Emission Spectroscopy (ICP-OES) and Atomic Fluorescence Spectrometry (HG-AFS) at the Center for Water Analysis, University of South Florida. Total arsenic concentration for each sample was analyzed by HG-AFS on a PSA 10.055 Millennium Excalibur system. In preparation for AFS analysis, 10 mL of the sample solution was treated with 30% c oncentrated HCl, 2% saturated potassium iodide (KI) solution, and deionised water (DDI) with a final dilution volume of 50

PAGE 37

25 mL (5:1). This special treatment of the sa mples cause the reduction of As (V) to As (III) prior to the formati on of the arsenic hydride (3AsH) via addition of sodium tetraborohydride (4NaBH). The arsenic hydride generator is based on the reaction of sodium borohydride, hydrochloric acid and the sample. Formation of hydrogen free radical: NaBH4 + 3 H2O + HCl H3BO3 + 8H+ NaCl Formation of the volatile arsenic hydride (gas) 8H+ As3+AsH3 + H2 excess In a consequence, the AsH3 is then atomized in a hydrogen flame and concentrations are determined by fluorescence spectrometry. The elements Ca, Fe, Mg, Mn, S, P, Si and Al were analyzed by ICP-OES on a Perkin-Elmer Optima 2000 DV spectromete r. Sample preparation consisted of measuring 2 mL of the stored sample solution and was diluted with 8 mL of deionized water into a 10 mL centrifuge tube The sample dilution (5:1) is needed due to high acid concentration. The final solution is carried into the IC-OES via peristaltic pumps and the elements are atomized by hi gh temperature argon plasma and detected by emission spectrometry. Acid blanks for digestion, HG-AFS, and HG-ICP-OES did not revealed any detectable arsenic concentrations. Backgr ound signal drift monitor was less that 2%.

PAGE 38

26 Electron-Probe Microanalyser – Wave Dispersive Spectrometry The 16 polished thin sections with va riable arsenic concentrations and lithological compositions from each Formation/Member of the Hawthorn Group were chosen for the electron-probe microanaly sis – wave dispersive spectrometry (EMPA or Electron Microprobe) using a JEOL 8200 instrument at the Earth & Planetary Sciences Department, University of Ne w Mexico. Operating conditions of the electron microprobe were 20 kV acceler ating voltage, a spot size of 5 m, and a 20nA current. The electron microprobe was used fo r spot analysis and to create several chemical maps for examination of arseni c distribution in matrix and individual minerals. Statistical Methods To estimate statistical properties of th e analyzed elements the SPSS statistics software was used. The probability P-P plot s for the decimal logarithm of arsenic, iron and sulfur concentrations were created to determine if the variable is normally distributed (Landau and Everitt, 2004). Th e normal P-P statistics plot compares the observed cumulative distribution function of the variable against the cumulative distribution function that would be expected if the data were normally distributed (Swan and Sandilands, 1995). Therefore, if a value comes from a normal distribution, points on the plot will gr oup around a straight line. In addition, the bell-sha ped frequency histograms of the Hawthorn Group samples were generated to evaluate the distribution of a single numeric variable

PAGE 39

27 (Landau, Everitt, 2004). A histogram disp lays the distribution of a quantitative variable by showing the relative concentra tion of data points al ong different intervals or sections of the scale on which the da ta are measured (Landau, Everitt, 2004). Determination of the normal P-P plots and frequency histograms allowed to find a mean ( ) and standard deviation ( ) from the normal arsenic distribution and to get a normal cumulative distribution f unction (CDF.Normal). The CDF.Normal ( quant mean, stddev ) function gives the area under a normal curve with the given mean and standard deviation for values less than quant (known concentration) (Landau, Everitt, 2004), or in other words, CDF.Normal shows the probability of a concentration Q to be less than quant i.e. CDF.Normal ( quant, mean, stddev ) = P (Q< quant) P (Q< quant) = quantf(x)dx, where 2 22 2 1 22 / ) (x / -e ) ( f(x) is a density function for normal distribution with the given mean ( ) and standard deviation ( ) (Shiryaev, 1996). The normal P-P plots, frequency hi stograms and normal cumulative distribution functions were created for all Hawthorn samples and for selected interval samples. In addition, the survivor functions for each formation/member of the Hawthorn Group were found. The survival f unction is the probability that a concentration Q has a value greater than quant i.e. S (quant) = P (Q > quant) = 1 – P (Q < quant) (Evans et al., 2000; Shiryaev, 1996).

PAGE 40

28 CHAPTER FOUR RESULTS Petrography and Mineralogy Stereo and Petrographic Microscopy Arcadia Formation The inspection of the Arcadia Formation samples including the Tampa and the Nocatee Members demonstrates diverse lithologic and mineralogic compositions. Most samples consist of carbonate materi al (limestones and dolostones) with a variable amount of silicicl astic component. The general lithologic char acteristics of the Arcadia Formation, Tampa and the Nocatee Members are demonstrated in Appendices A-C. The siliciclastics are primar ily composed of gray and grayish green clays, quartz, and phosphatic material. Th e Tampa Member contains no or only a minor amount of phosphatic matter. In addi tion, the examination of sediments reveals presence of some minor mineral phases, such as pyrite, gypsum, chert, secondary calcite, feldspar, and hydrous ferric oxides The HFO were frequently observed as stains or rings around pyrites. Framboidal a nd euhedral pyrite cr ystals are ubiquitous throughout the Arcadia Formation. Organic matter was observed in several samples and revealed heterogeneous distribution throughout the undifferentiated Arcadia

PAGE 41

29 Formation. Detailed lithologic descriptions of the Arcadia sediments correspond to the reported studies of the Arcadia Fo rmation (Wingard et al., 1993; Scott, 1990, 1988). Thin sections with variable arsenic con centrations were investigated with the polarizing microscope with reflected and transmitted light, and demonstrated the presence of different mineralogies, such as phosphate, calcite, dolomite, feldspar, pyrite, quartz, clays, and hydrous ferric oxid es. Pyrite crystals were observed in about 90% of the thin sections occurring in th e sediment matrix and as inclusions in phosphate grains and calcite cr ystals. Figure 5 illustrates the presence of framboidal pyrites in the Arcadia Formation. Figure 5. Backscattered images of framboi dal pyrite (py) in carbonate matrix (carb) from sample 20-143 (Arcadia Formation). py py carb

PAGE 42

30 Peace River Formation The analyses of Peace River samples displays that the majority of sediments are generally composed of siliciclastics such as quartz sands, gray to dark greenish gray clays, and substantial amount of phos phates. The occurrence of several minor mineral phases revealed framboidal and euhedral pyrite, gypsum, native sulfur, secondary calcite, feldspar, and hydrous ferric oxides (HFO) or Fe-oxyhydroxides. These lithologic descriptions coincide w ith the reported studies of the Peace River Formation (Green at al., 1995; Compton et al., 1993; Scott, 1990, 1988). The general lithologic characteristics of the Peace River sediments are illustrated in Appendix D. Using the polarizing microscope with reflected and transmitted light on thin sections of the Peace River sediments with variable arsenic concentrations revealed the presence of different mineralogies, su ch as pyrite, phosphate, calcite, gypsum, dolomite, feldspar, quartz, clays, and hydrous ferric oxides. Generally, about 90% of all thin sections contained pyr ite crystals in the sediment matrix and several samples revealed the inclusions of pyrite in phosphate grains. Scanning Electron Microscopy Based on geochemical results several sa mples with high arsenic levels were selected for a more focused mineral ogical analysis usi ng scanning electron microscopy (SEM). The SEM of the selected samples from the Arcadia Formation and the Tampa Member confirm the existence of both framboidal a nd euhedral pyrite crystals (Figures 6, 7). Framboidal pyrites are approximately less than 10 m in

PAGE 43

31 diameter and consisted of e uhedral pyrite micro-crystals (Figure 6). SEM shows that pyrite was randomly scattered, occurring w ith clays, phosphate nodules and organic material. Figure 6. Scanning electron micrograph of fram boidal pyrite (py) and kaolinite (kaol) in sample 22-170 from the Tampa Member (arsenic concentration of the bulk sample is 14.0 ppm). Figure 7. Scanning electron micrograph of e uhedral pyrite (py) in sample 4-1-599 from the Arcadia Formation (arsenic con centration of the bulk sample is 7.5 ppm). kaol py py

PAGE 44

32 Bulk Chemical Composition Hawthorn Group (All samples) In the 362 Hawthorn Group samples, concen trations of arsenic vary from 0.1 ppm to as high as 69.0 ppm with a mean () of 5.6 ppm and standard deviation ( ) of 7.1 ppm (Table 2). The mean includes both interval samples and samples of the special interest and, therefore, should be used with caution. Bulk-rock chemical analyses by ICP-OES show that the most appreciable linear correlation for the Hawthorn Group sedi ments exists between S and Fe with R2 of 0.87, which could be due to the outlier effect (Swan and Sandilands, 1995) caused by sample 12 125(2) (Figure 8A). Elimin ation of the outlier point with the anomalously high concentration of Fe and S show a correlation of R2 = 0.77 (Figure 8B). Figure 8 displays the pyrit e line in case if only pyrite as a source of Fe and S is dissolved and analyzed. Some of the Ha wthorn samples plot above and under the pyrite line indicating that ir on is probably present with in hydrous ferric oxides and sulfur within gypsum. Correlation matrix between Ca, Fe, Mg, M n, Si, S, P, Al, and As for all 362 samples from the Hawthorn Group is demonstrated in Table 3. Hawthorn Group (Interval samples) The arsenic concentrations of the 285 interval samples from the Hawthorn Group range from 0.1 ppm to 40.8 ppm with a mean of 5.0 ppm ( is 5.8 ppm) (Table 2).

PAGE 45

33 Table 2. Maximum, Minimum, Mean a nd Standard Deviation of arsenic concentrations in ppm for the Hawtho rn Group and its Formations/Members. Maximum Minimum Mean Standard Deviation (n) Hawthorn Group (all samples) 69.0 0.1 5.6 7.1 362 Hawthorn Group (interval samples) 40.8 0.1 5.0 5.8 285 Peace River Formation 40.8 0.4 8.8 8.6 55 Undifferentiated Arcadia Formation 36.0 0.1 5.7 6.2 205 Tampa Member 15.2 1.2 3.0 3.7 75 Nocatee Member 69.0 0.5 6.5 13.1 27

PAGE 46

34 (A) R2 = 0.870 20000 40000 60000 80000 100000 120000 140000 020000400006000080000100000120000Fe (ppm)S (ppm) 12-125(2) Pyrite Line R2 = 0.770 5000 10000 15000 20000 25000 30000 35000 05000100001500020000250003000035000Fe (ppm)S (ppm) Pyrite Line Figure 8. Diagrams showing correlation be tween Fe and S in the Hawthorn Group all data (A) and without the outlier (B); see text for additional information. (B)

PAGE 47

35 Table 3. Correlation matrix for the Hawthorn Group (all 362 samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.43 -0.13 -0.24 -0.29 -0.27 -0.12 -0.64 -0.29 Fe 1.00 -0.03 0.38 0.25 0.87 0.27 0.57 0.35 Mg 1.00 0.23 0.09 -0.01 0.00 0.04 0.04 Mn 1.00 0.11 0.30 0.36 0.41 0.27 Si 1.00 0.22 0.28 0.24 0.28 S 1.00 0.29 0.35 0.40 P 1.00 0.28 0.14 Al 1.00 0.25 As 1.00 R2 = 0.69 0 5000 10000 15000 20000 25000 30000 35000 050001000015000200002500030000 S (ppm)Fe (ppm) Figure 9. Correlation between Fe and S fo r the Hawthorn Group interval samples.

PAGE 48

36 Bulk-rock analyses by ICP-OES reveal ed a significant degree of linear correlation between Fe and S, with R2 value of 0.69 for the all interval samples (Figure 9). Correlation matrix for all 285 in terval samples from the Hawthorn Group is demonstrated in Table 4. Table 4. Correlation matrix for the Ha wthorn Group (285 interval samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.55 -0.17 -0.24 -0.25 -0.40 -0.16 -0.59 -0.09 Fe 1.00 0.04 0.47 0.31 0.69 0.30 0.63 0.32 Mg 1.00 0.27 0.09 0.09 -0.02 0.07 0.01 Mn 1.00 0.15 0.42 0.38 0.42 0.07 Si 1.00 0.37 0.32 0.26 0.06 S 1.00 0.37 0.35 0.26 P 1.00 0.33 0.19 Al 1.00 0.25 As 1.00 Undifferentiated Arcadia Formation The arsenic concentrations of the undi fferentiated Arcadia Formation vary from 0.1 ppm to 36.0 ppm (Table 2). The mean of 205 samples is of 5.7 ppm ( is 6.2 ppm). Appendix B shows total arsenic c oncentrations for 205 samples from the undifferentiated Arcadia Formation. About 88% of all samples have less that 10 ppm of arsenic and approximately 11% less that 1 ppm (Appendix E). Samp les with mostly pure limestone and

PAGE 49

37 dolostone show low concentration of arseni c. High arsenic concentrations associate with the contribution of pyr ite, clays, hydrous ferric oxides, and phosphates. Bulk-rock chemical analyses by ICP-OES illustrate that the most significant linear correlation for the undifferentiate d Arcadia Formation sediments exists between S and Fe with R2 of 0.81 (Figure 10) and between Al and Fe (clay material) with R2 of 0.74. Correlation matrix for all 204 sa mples from the Arcadia Formation is shown in Table 5. R 2 = 0.810 5000 10000 15000 20000 25000 30000 35000 010000200003000040000S (ppm)Fe (ppm) Figure 10. Correlation between Fe and S for the Undifferentiated Arcadia Formation.

PAGE 50

38 Table 5. Correlation matrix for the undiffe rentiated Arcadia Formation (205 samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.46 -0.17 -0.19 -0.28 -0.32 -0.06 -0.51 -0.14 Fe 1.00 -0.06 0.38 0.18 0.81 0.14 0.74 0.30 Mg 1.00 0.19 -0.01 -0.08 -0.11 -0.03 0.00 Mn 1.00 0.03 0.37 0.33 0.35 0.12 Si 1.00 0.18 0.23 0.23 0.02 S 1.00 0.27 0.51 0.28 P 1.00 0.21 0.10 Al 1.00 0.35 As 1.00 Tampa Member The arsenic concentrations of the Ta mpa Member of the Arcadia Formation range from 0.2 ppm to 15.2 ppm (Table 2). The mean value for 75 samples is of 3 ppm ( is 3.7 ppm). Values for all 75 samples from the Tampa Member are listed in Appendix B. Approximately 92% of all samples cont ain less that 10 ppm of arsenic and about 39% less that 1 ppm (Appendix B). Samples of a pure carbonate sandstone, limestone and dolostone consistently demons trate low arsenic concentrations. Arsenic concentrations increase with increasing abundance of pyrite, clays, and phosphates. Bulk-rock analyses by ICP-OES reveal ed a significant degree of linear correlation between Al with Fe and S (clay material), with R2 of 0.76 and 0.78

PAGE 51

39 respectively. In addition, high degree of linear correlati on found between Fe and S, with R2 value of 0.63 (Figure 11). Correlation ma trix for all 75 samples from the Tampa Member is shown in Table 6. R2 = 0.63 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 050001000015000 S (ppm)Fe (ppm) Figure 11. Correlation between Fe and S for the Tampa Member. Table 6. Correlation matrix for the Tampa Member of the Arcadia Formation (75 samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.52 -0.27 -0.18 -0.28 -0.34 -0.29 -0.58 -0.17 Fe 1.00 0.24 0.44 0.19 0.63 0.51 0.76 0.53 Mg 1.00 0.54 0.23 0.24 0.03 0.22 0.11 Mn 1.00 0.25 0.30 0.05 0.29 0.23 Si 1.00 0.16 0.08 0.16 0.23 S 1.00 0.58 0.78 0.61 P 1.00 0.48 0.16 Al 1.00 0.55 As 1.00

PAGE 52

40 A combination of ICP-OES and HG-AFS re sults revealed a significant degree of linear correlation between As and S, with R2 of 0.61(Figure 12). R 2 = 0.610 2000 4000 6000 8000 10000 12000 14000 05101520As (ppm)S (ppm) Figure 12. Correlation between As and S for the Tampa Member. Nocatee Member The arsenic concentrations of the No catee Member of the Arcadia Formation range from 0.5 ppm to as high as 69.0 ppm (Table 2). The mean value for 27 samples is 6.5 ppm ( is 13.1 ppm). Arsenic values for all 27 samples from the Nocatee Member are demonstrated in Appendix C. Approximately 88% of all samples cont ain less that 10 ppm of arsenic and roughly 23% less that 1 ppm (A ppendix C). Arsenic concentrat ions increase with the abundance of pyrite, hydrous ferric oxides, clays, and phosphate. The sample 12-529

PAGE 53

41 from the Nocatee Member represents the hi ghest arsenic concentr ation (69.0 ppm) of the all Hawthorn Group samples. Bulk-rock analyses by ICP-OES reveal ed a significant degree of linear correlation between Fe and S, with R2 of 0.85 (Figure 13). In addition, a high degree of linear correlation fou nd between Fe and Al (clay material), with a R2 value of 0.81. Correlation matrix for all 27 samples from th e Nocatee Member is shown in Table 7. R 2 = 0.850 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 050001000015000S (ppm)Fe (ppm) Figure 13. Correlation between Fe and S for the Nocatee Member.

PAGE 54

42 Table 7. Correlation matrix for the Nocat ee Member of the Arcadia Formation (27 samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.44 -0.12 -0.39 -0.28 -0.38 -0.01 -0.36 -0.08 Fe 1.00 0.25 0.77 0.50 0.85 0.03 0.81 0.49 Mg 1.00 0.31 -0.05 0.13 0.29 0.42 0.002 Mn 1.00 0.58 0.61 0.10 0.45 0.11 Si 1.00 0.74 0.16 0.44 0.61 S 1.00 0.12 0.51 0.51 P 1.00 0.05 0.001 Al 1.00 0.28 As 1.00 Peace River Formation The total arsenic concentrations of the Peace River Formation range from 0.4 ppm to 40.8 ppm (Table 2). The mean value for 54 samples is 8.8 ppm ( is 8.6 ppm). Values for all 55 samples from the Peace River Formation are listed in Appendix D. Arsenic concentrations of the Peace Ri ver Formations are diverse but can be explained by different lithol ogical compositions of sedime nts. Approximately 70% of all samples have arsenic concentrations le ss that 10 ppm, and about 7% less than 1 ppm (Appendix D). Samples that represent pu re carbonate matrix, sandstone with no visible trace minerals contain low arsenic concentrations. Arsenic concentrations increase with increasing abundance of pyrite, clays, hydrous ferric oxides, and phosphates.

PAGE 55

43 The ICP-OES results show that the str ongest linear correlation for the Peace Formation exists between Fe and S, with corresponding R2 of 0.94 (Figure 14A), which could be due to the outlier effect (Swan and Sandilands, 1995). According to geochemical studies, the outlier (sample 12-125(2)) has anomalously high values of iron, sulfur and phosphorous compared to all Hawthorn Group sediments. Removing the outlier from the plot results in a signi ficantly lower degree of linear correlation, R2 = 0.59 (Figure 14B). This is because analyz ed samples contain not only pyrite, but also composed of hydrous ferric oxides (HFO) and gypsum, as a source of iron and sulfur. The correlation matrix for all 55 samples from the Peace River Formation is shown in Table 8. R 2 = 0.940 20000 40000 60000 80000 100000 120000 020000400006000080000100000120000140000S (ppm)Fe (ppm) 12-125(2) (A)

PAGE 56

44 R 2 = 0.590 5000 10000 15000 20000 25000 30000 050001000015000200002500030000S (ppm)Fe (ppm) Figure 14. Diagrams showing correlation between Fe and S in the Peace River Formation for all data set (A) and with re moved outlier (B); see text for additional information. Table 8. Correlation matrix for the Peace River Formation (55 samples); significant correlations are in bold. Ca Fe Mg Mn Si S P Al As Ca 1.00 -0.05 0.44 0.04 0.11 0.03 0.30 -0.39 0.06 Fe 1.00 -0.16 0.23 0.18 0.94 0.27 0.15 0.15 Mg 1.00 0.14 -0.19 -0.10 -0.26 -0.23 -0.003 Mn 1.00 -0.09 0.19 0.21 0.29 0.01 Si 1.00 0.19 0.29 -0.02 0.02 S 1.00 0.27 0.02 0.12 P 1.00 0.13 0.29 Al 1.00 0.004 As 1.00 (B)

PAGE 57

45 Electron-Probe Microanalyser – Wave Dispersive Spectrometry Hawthorn Group (All samples) After determination of the total arsenic concentrations, 60 polished thin sections of the Hawthorn Group samples w ith the high bulk arsenic concentrations were selected for a more detailed ch emical investigation and mineralogical association. The electronpr obe microanalyses of 16 thin sections with different lithological composition revealed that substant ial arsenic concentrations are present in framboidal and euhedral pyrite. The EMPA was used for spot analysis and to generate several chemical maps for examination of arsenic distribu tion in matrix and individual minerals. About 126 single pyrite crystals were examined by EMPA. Arsenic concentrations in these pyrites ranged from 0 ppm to as high as 8260 ppm with mean value of 1272 ppm and standard deviation of 1379 ppm (Table 9). Values of arsenic concentrations for all 126 pyrites from th e Hawthorn Group are listed in Appendix I. Prior studies of framboidal pyrite in Suwa nnee Limestone (Price and Pichler, 2004, in review; Price, 2002) revealed significant ar senic enrichment ranging from 100 to as high as 11,200 ppm. The EMPA elemental mapping of cl ays, pyrite, dolomite, quartz and phosphorite demonstrates that high concentratio ns of arsenic are associated with the framboidal, euhedral pyrite and hydrous ferric oxides and shows heterogeneous distribution of arsenic within all analyzed samples.

PAGE 58

46 Table 9. Electron microprobe results for arse nic in pyrites for the Formation/Member of the Hawthorn Group (in ppm). Maximum MinimumMean Standard Deviation (n) Peace River Formation 4160 0 772 1082 30 Undifferentiated Arcadia Formation 8260 0 1437 1569 48 Tampa Member 3220 0 1004 770 39 Nocatee Member 5710 560 2884 1896 9 Undifferentiated Arcadia Formation Arsenic concentrations in pyrites from the undifferentiated Arcadia Formation range from 0 ppm to 8260 ppm (Table 9). The mean for 48 pyrites is 1437 ppm ( is 1569 ppm). Values for all 48 pyrites from th e undifferentiated Arcadia Formation are listed in Appendix I. The elemental mapping of the internal chemical composition of the phosphate nodule (sample 5-1-235) reveals the occurren ce of pyrite crystals (Figure 15) and demonstrates arsenic enrichment in pyrit es to as high as 3700 ppm (0.37 weight %) compared to phosphate matrix with arsenic of 0 ppm (Table 10). The EMPA elemental mapping of samp le 4-1-501 demonstrates arsenic enrichment in both pyrites and hydrous ferri c oxides (Figure 16, Table 11), and shows heterogeneous distribution of arsenic within the sample.

PAGE 59

47 Figure15. Elemental mapping of phosphorite in sample 5-1-235 (Arcadia Formation). Background was not subtracted; relative con centrations increase with a change in color from blue to yellow to red.

PAGE 60

48 Table 10. Electron microprobe results for ar senic in pyrites and phosphate matrix in sample 5-1-235 for the undifferentiated Arcadia Formation (wt. %) Sample S As Fe P Ca Total 5-1-235map-1 51.21 0.03 44.57 95.80 5-1-235map-2 47.18 0.12 41.48 88.78 5-1-235map-3 45.73 0.37 41.72 87.83 5-1-235map-4 1.46 0.00 0.82 5.00 33.11 40.39 5-1-235map-5 0.65 0.00 0.45 4.73 26.96 32.79 5-1-235map-6 0.66 0.00 0.43 4.58 25.86 31.52 Figure 16. (A) Photograph of sample 4-1501 (undifferentiated Arcadia Formation); (B) Backscattered image of pyrites (py), hydrous ferric ox ides (HFO), and carbonate matrix (carb). carb (A) HFO py (B)

PAGE 61

49 Table 11. Electron microprobe results for ar senic in pyrites and hydrous ferric oxides in sample 4-1-501 for the undifferentiate d Arcadia Formation (in wt% percent) Sample S As Fe Total 4-1-501-1 34.333 0.046 35.593 69.97 4-1-501-2 33.371 0 39.865 73.24 4-1-501-3 41.008 0 43.05 84.06 4-1-501-4 38.601 0.047 48.143 86.79 4-1-501-5 35.618 0 45.718 81.34 4-1-501-6 2.235 0.054 38.535 40.82 4-1-501-7 2.282 0.018 38.457 40.76 4-1-501-8 1.026 0.018 39.687 40.73 Tampa Member Arsenic concentrations in pyrites from the Tampa Member range from 0 ppm to 3220 ppm (Table 9). The mean value for 39 pyrites is 1004ppm ( is 770 ppm). Values for all 39 pyrites from the Tamp a Member are listed in Appendix I. The electron microprobe an alysis of sample 22-170 for 31 pyrites evidently illustrates significantly range of arsenic from 10 ppm to as high 2,180 ppm in pyrite crystals (Appendix I). These results confirm occurrence of diverse arsenic concentrations in pyrite crystals ev en within one analyzed sample.

PAGE 62

50 Nocatee Member The electron microprobe an alysis of sample 12-529 from the Nocatee Member for nine pyrites showed that arsenic concen trations vary from 560 ppm to as high as 5710 ppm with mean value of 2884 ppm and standard deviation of 1896 ppm (Table 9). Bulk arsenic analysis of all Hawthorn Group samples showed that sample 12-529 has the highest arsenic concen tration of 69 ppm (Appendix C). Peace River Formation Arsenic concentrations in pyrites fr om the Peace River Formation range from 0 ppm to 4160 ppm (Table 9). The mean value for 30 pyrites is 772 ppm ( is 1082 ppm). Values for all 30 pyrites from the Peace River Formation are demonstrated in Appendix I. The elemental mapping of sample 12 – 125 clearly shows the dominated arsenic concentrations in pyr ite compare to clays and phosphate (Figure 18). For the bulk-rock analysis, sample 12-125 was divided into two parts due to its heterogeneity (Figure 17). Total arsenic for sample 12-125(1) was 8.1 ppm and 26.7 ppm for 12125(2) (Appendix D). Sample 12 – 125 (2) pos sibly represents a burrow fill with a significant amount of pyrite in the phosphate matrix.

PAGE 63

51 Figure 17. (A) Photograph of sample 12 125 (Peace River Formation) composed of clays (1 = 12 125(1)) and pyrite phosphate matrix (2 = 12-125(2)); (B) Photomicrograph of contact between sample (1) and (2); (C) Backscattered image of pyrite (py), clay (cl) and phosphate (ph). 1 2 (C) py cl ph cl (A) (B)

PAGE 64

52 Figure 18. Elemental mapping of pyrite in sample 12 – 125 (Peace River Formation). Background subtracted; relative concentrations increase with a change in color from blue to yellow to red.

PAGE 65

53 -1.0-0.50.00.51.01.5Log As (ppm) 0 10 20 30 40Frequency Mean = 0.495 Std. Dev. = 0.4976 N = 362Probability Analysis The statistical analysis indicated that arsenic (As), sulfur (S) and iron (Fe) concentrations for all Hawthorn samples fo llow a lognormal distri bution (Figures 1921), i.e., all points follow a straight line. Figures 19-21 demonstrate the bell-s haped frequency histograms indicating the lognormal distribution of analyzed el ements (As, S and Fe). Histograms were generated to evaluate the dist ribution of an element and to calculate values of a mean ( ) and standard deviation ( ). Determination of and of the normal arsenic distribution allow the app lication of the normal cumu lative distribution function (CDF.Normal) (Figures 22, 24). Figure 19. Frequency histogram and nor mal P-P plot of log-transformed arsenic concentrations from the Hawthorn Group 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Observed cumulative Probability Expected cumulative probability

PAGE 66

54 0.0 0.2 0.4 0.6 0.8 1.0Observed Cumulative Probability 0.0 0.2 0.4 0.6 0.8 1.0Expected Cumulative Probability 2.0 4.0Log Fe (ppm) 0 10 20 30 40 50 60Frequency Mean = 3.301 Std. Dev. = 0.5919 N = 362 Figure 20. Frequency histogram and normal P-P plot of log-transformed sulfur concentrations from the Hawthorn Group Figure 21. Frequency histogram and norma l P-P plot of log-transformed iron concentrations from the Hawthorn Group 20 2.5 30 3.5 404.550Log S (ppm) 0 10 20 30 40 50 60 Mean = 3.351 Std. Dev. = 0.4538 N = 362Frequency 0.0 0.2 0.4 0.6 0.8 1.0Observed Cumulative Probability 0.0 0.2 0.4 0.6 0.8 1.0Expected Cumulative Probability

PAGE 67

55 The CDF.Normal ( quant, mean, stddev ) function gives the area under a normal curve with the given mean and st andard deviation for values less than quant (known concentration) (Landau, Everitt, 2004). 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 -1.5-1-0.500.511.52 Log As (ppm)Cumulative Function Figure 22. Cumulative distribution function of log-transformed arse nic concentrations for the all Hawthorn Group The statistical analysis indicated that arsenic concentrations for the interval Hawthorn samples also follows a lo gnormal distribution (Figure 23).

PAGE 68

56 -1.00-0.500.000.501.001.50Log As (ppm) 0 10 20 30Frequency Mean = 0.4575 Std. Dev. = 0.4826 N = 285 Figure 23. Frequency histogram and normal P-P plot of log-transformed arsenic concentrations from the Hawthorn Group interval samples 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 -1.5-1.0-0.50.00.51.0152.0Log As (ppm)Cumulative Function Figure 24. Cumulative distribution function of log-transformed arsenic concentrations for the interval Hawthorn samples. 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Expected cumulative probability Observed cumulative Probability

PAGE 69

57 In addition, survivor probability func tions of log-transformed and actual arsenic concentrations were created fo r Arcadia Formation (Figure 25), Tampa (Figure 26) and the Nocatee (Figure 27) Me mbers of the Arcadia Formation, and the Peace River Formation (Figure 28). The surviv al function is the probability that a concentration Q has a value greater than quant i.e. S (quant) = P (Q > quant) = 1 – P(Q < quant) (Evans et al., 2000; Connor et. al., 2003). Detailed examinations of the survivor functions indicate a general decrease of arsenic concentration from the Peace River Formation to the Tampa Member of the Arcadia Formation with the increasing valu es in the Nocatee Member of the Arcadia Formation (Table 12, Figure 29). For example, it shows that, there is a probability of 0.06 of finding a sample from the Peace Rive r Formation with arsenic concentration greater than 30 ppm and only 0.01 for the Ta mpa Member of Arcadia Formation. On the other hand, probabilities of arsenic w ith corresponding values for the Arcadia Formation and the Nocatee Member of Arcadia Formation are approximately the same (Table 12). Generally, the distribution of arsenic concentrations depends on the presence of pyrite, clays and phosphate ma terial, and, according to Scott (1988), the siliciclastics are dominant throughout the Pe ace River Formation and more prevalent within the Nocatee Member as compar ed to the entire Arcadia Formation.

PAGE 70

58 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -1.5-1-0.500.511.52Log As(ppm)Survivor Function 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 010203040506070As (ppm)Survivor Functio n Figure 25. Survivor probability functions of log-transformed (A) and actual (B) arsenic concentrations fo r the Arcadia Formation. (A) (B)

PAGE 71

59 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -15-1-0.500.51152Log As(ppm)Survivor Function 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 01 02 03 0As (ppm)Survivor Functio n Figure 26. Survivor probability functions of log-transformed (A) and actual (B) arsenic concentrations for the Tamp a Member of the Arcadia Formation. (B) (A)

PAGE 72

60 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -1.5-1-0.500.511.52Log As (ppm)Survivor Function 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0102030405060 As (ppm)Survivor Function Figure 27. Survivor probability functions of log-transformed (A) and actual (B) arsenic concentrations fo r the Nocatee Member of the Arcadia Formation. (B) (A)

PAGE 73

61 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -1.5-1.0-0.50.00.51.01.52.0Log As (ppm)Survivor Function 0 0.1 02 03 0.4 05 0.6 0.7 08 09 1 01 0203040506070As (ppm)Survivor Functio n Figure 28. Survivor probability functions of log-transformed (A) and actual (B) arsenic concentrations for the Peace River Formation (A) (B)

PAGE 74

62 Table 12. Probability of arsenic co ncentrations being larger than corresponding values th roughout the Hawthorn Group Probability Hawthorn Group Unit Q > 1ppm 5ppm 15ppm 30ppm Peace River Formation 0.95 0.55 0.18 0.06 Arcadia Formation 0.89 0.36 0.08 0.02 Tampa Member 0.64 0.16 0.03 0.01 Nocatee Member 0.82 0.34 0.09 0.03 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Probability Peace River Formation Arcadia Formation Tampa Member Nocatee Member 1 ppm 5 ppm 15 ppm 30 ppm Figure 29. Diagram showing the probability of arsenic distribution throughout the Hawthorn Group

PAGE 75

63 CHAPTER FIVE DISCUSSION Abundance of Arsenic in the Hawthorn Group The abundance of arsenic in the upper c ontinental crust significantly varies from 1.5 ppm (Taylor et al., 1985) to 4.8 pp m (average data from Sims et al., 1990; Gao et al. 1998). These values of arsenic concentrations depend on the lithology of individual rocks. The average for limest one geostandard GSR-6 is reported as 2.6 ppm (Baur, Onishi, 1969). The average con centrations for shale and river mud are 12.4 and 8.4 ppm respectively (Govindar aju, 1994). The average value for phosphorite is 23 ppm (Li, 2000). The present research demonstrates that arsenic occurs th roughout the whole Hawthorn Group and varies drastically from the formation to formation (Table 2). Figure 30 shows the distribution of arsenic mean values for the each formation and member of the Hawthorn Group. It noticeab ly indicates the decrease of arsenic concentration with depth from the Peace River Formation to the Tampa Member of the Arcadia Formation. The same distribution patterns occur for iron (Fe), sulfur (S), aluminum (Al), and phosphorous (P) (Figur e 32). According to Scott (1988), the siliciclastic component, such as clay, phos phate, and quartz sand is dominant in the Peace River Formation and its input to the Hawthorn Group decreases with depth.

PAGE 76

64 Therefore, the overall decrease of the arseni c concentrations with depth correlate with a source of siliciclastic content. The Nocatee Member of the Arcadia Formation reveals much higher arsenic mean concentr ation which could be due to the outlier effect (Swan and Sandilands, 1995) caused by sample 12 529 with the highest arsenic value of the all Hawthorn Group sa mples (69 ppm) (Figure 30A). Elimination of the outlier results in lower arsenic m ean value (4.1 ppm) for the Nocatee Member (Figure 30B). In addition, the higher contribution of siliciclastic material in the Nocatee Member (Scott, 1988) demonstrates th e elevated values of Fe, S, Al and P compared to those in the Tampa Member (Figure 31). Spatial distribution of the mean arse nic concentrations for each core was determined for the Hawthorn Group all data (Figure 32), Arcadia Formation (Figure 33), Tampa (Figure 34) and the Nocatee (Figure 35) Members of the Arcadia Formation, and the Peace Ri ver Formation (Figure 36). 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0Mean As (ppm) Peace River Formation Undifferentiated Arcadia Formation Tampa MemberNocatee Member (A)

PAGE 77

65 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0Mean As (ppm) Peace River Formation Undifferentiated Arcadia Formation Tampa MemberNocatee Member Figure 30. Distribution of the mean arseni c concentrations throughout the Hawthorn Group all data (A) and without the ou tlier (B); see text for additional information. 0 2000 4000 6000 8000 10000 12000 14000 16000Mean (ppm) Peace River Formation Undifferentiated Arcadia Formation Tampa MemberNocatee Member Mean S (ppm) Mean Fe (ppm) Mean Al (ppm) Mean P (ppm) Figure 31. Distribution of the mean S, Fe Al and P concentrations throughout the Hawthorn Group (B)

PAGE 78

66 Figure 32. Spatial distribution of the mean concentrations (in ppm) in the Hawthorn Group all data; size of point indicates re lative mean of arsenic concentration.

PAGE 79

67 Figure 33. Spatial distribution of the mean concentrations (in ppm) in the Arcadia Formation; size of point indicates re lative mean of arsenic concentration.

PAGE 80

68 Figure 34. Spatial distribution of the mean concentrations (in ppm) in the Tampa Member of the Arcadia Formation; size of point indicates relativ e mean of arsenic concentration.

PAGE 81

69 Figure 35. Spatial distribution of the mean concentrations (in ppm) in the Nocatee Member of the Arcadia Formation; size of point indicates relativ e mean of arsenic concentration.

PAGE 82

70 Figure 36. Spatial distribution of the mean c oncentrations (in ppm) in the Peace River Formation; size of point indicates re lative mean of arsenic concentration.

PAGE 83

71 Sources of Arsenic in the Hawthorn Group Detailed mineralogical and geochemi cal study the Hawthorn Group sediments demonstrates four major po ssible sources of arsenic: Substitution at any of the fluorap atite sites in Francolite; Substitution in the crystal structure of sulfide minerals such as pyrite and arsenopyrite; Adsorption or ion exchange ont o clay and organic matter; Adsorption or coprecipitation with hydrous ferric oxides (HFO). The following section is a brief expl anation of arsenic sources in the Hawthorn Group. Francolite (Carbonate Fluorapatite) The highly open crystal structure of francolite permits substitution at any of the fluorapatite sites, e.g. Na+, Mg2+, Sr2+ for Ca2+; OH-, AsO 3CrO 2-, VO 3for PO 3-; and Cl-, Brfor F (Shields, 2002). According to Smedley and Kinniburgh (2003) calcium phosphate or apatite can contain up to 1000 mg/kg of arsenic. On the other hand, Stow (1969) did not reveal any corre lation between arsenic and phosphorous in the Bone Valley Member of the Hawthorn Group. The combination of the ICP-OES and HG-AFS showed no correlation between arsenic and phosphorous. However, the

PAGE 84

72 EMPA elemental mapping of the internal chemical composition of the phosphate nodule from the undifferentiated Arcadia Form ation revealed the occurrence of pyrite crystals with arsenic enrichment as high as 3700 ppm (0.37 wt. %) compared to phosphate matrix with arsenic of 0 ppm (Table 10, Figure 15). Pyrite Detailed lithologic exam inations of the Hawthorn Group sediments with stereo microscope and SEM revealed the existence of unevenl y distributed pyrite occurring mostly with greenish clays, phosphate and organic material. These lithological components are deposited under the reducing environment. Examination of thin sections with the polarizing micr oscope demonstrated that euhedral and framboidal pyrites occur in a bout 90% of all samples as a minor mineral phase in the sediment matrix and as inclusions in phosphate grains a nd calcite crystals. Prior studies of sulfide minerals such as th e abundance and occurrence of pyrite in the Suwannee Limestone (Price, Pichler, 2004, in review; Price, 2003; Price, Pichler, 2002) revealed significant enrichment of arseni c in pyrite with concentrations as high as 11,200 ppm. Thomas and Sanders (1998) repo rted arsenic concentrations in pyrite framboids of up to 1000 ppm as a substitute element for sulfur in the FeS2 structure. Huerta-Diaz and Morse (1990) found arsenic concentrations in marine sedimentary pyrites of as much as 0.93 wt. %. Therefor e, sedimentary pyrite can be a significant sink and source of arsenic.

PAGE 85

73 The ICP-OES results revealed strong lin ear correlation be tween sulfur and iron (R2 = 0.87) confirming presence of pyrite (Figure 8). Lack of significant correlation between arsenic and sulfur or iron is probably due to the contribution of other sources of arsenic. The electron microprobe analyses of 16 thin sections with a different lithological composition revealed that substant ial arsenic concentrations are present in framboidal and euhedral pyrit e. Arsenic concentrations in 126 analyzed pyrites crystals range from 0 ppm to as high as 8260 ppm showing the heterogeneous distribution of arsenic within all samples (Table 9). Clay and Organic Matter Clays readily adsorb arsenic because of the oxide-like character of the edges of its grains (Claesson et al., 2003). Lit hologic examinations of the Hawthorn Group sediments revealed the abundance of green or even brownish green clays mostly in the Peace River Formation. Generally, green clays contained unevenly distributed pyrite and phosphate. The HG-AFS analysis of clay material generally showed high arsenic concentrations (Appendix A-D). Clays and organic substance have very small particle size, which therefore result in a large surface area per unit volume and ability to adsorb arsenic. Moreover the potential of organic materi al to generate complexes with heavy metals is due to the existence of oxygen-containing func tional groups such as carboxyl (COOH), hydroxyl (Oh), and carbonyl (C=O) (Eva ngelou, 1995). Detailed lithologic

PAGE 86

74 examinations of the Hawthorn Group samp les revealed the abundance of organic matter mostly in the Arcadia Formation. The AFS analysis of samples with organic substance revealed arsenic concentrati on of about 5 ppm. At the same time, concentration of arsenic in samples contai ning green clays with pyrite was as high as 69 ppm (Appendix C). Hydrous Ferric Oxides (HFO) It has been shown that ar senic incorporates into se diments by co-precipitation as hydrous ferric oxides (HFO), or is adsorbed onto extr emely high surface area of precipitated HFO (Hongshao, Stanforth, 2001; Hinkle et al., 1999; Evangelou, 1995; Bowell, 1994; Chao, Theobald, 1976). It has been reported the close connection between hydrous ferric oxides and arsenic (Pichler et al., 2000; Chao, Theobald, 1976). Stow (1969) reported that most of the arsenic in th e Bone Valley Member of the Hawthorn Group is adsorbed onto HFO. Detailed lithologic examinations revealed the occurrence of hydrous ferric oxides throughout the Hawthorn Group as stains or rings around pyrites. According to Compton et al. (1993) reworking of the Hawthorn Group sediment during periods of marine regressions caused oxidation of some pyrite and formation of hydrous fe rric oxides. The electron microprobe elemental mapping showed that hydrous ferric oxides from the undifferentiated Arcadia Formation contain as high as 540 ppm (0.054 weight %) of arsenic (Table 11, Figure 16).

PAGE 87

75 Quantified Role of Pyrite Based on the data presented above it a ppears evident that most arsenic is present in pyrite crystals. In order to quantify the responsibility of pyrite (FeS2) to contain arsenic we can ca lculate its abundance in th e Hawthorn Group sediments. According to the strong linear co rrelation between S and Fe (R2 = 0.87) suppose that Fe and S in our bulk rock studies are co mpletely derived from dissolved pyrite crystals. The calculated percent of pyrite amount was multiplied by arsenic concentration in pyrite of the each analyzed thin section and finally compared to the actual bulk concentration of arseni c obtained by AFS (Table 13). Table 13. Measured bulk arse nic concentrations and calcu lated arsenic in pyrite Sample Hawthorn Formation/ Member S, ppm Fe, ppm FeS2, ppm FeS2 (%) As, ppm (pyrite) Number of pyrite crystals As, ppm (p y rite) calc. As, ppm (bulk), meas. 9-30 Peace River 4479 3 905 8384 1 1337 15 11 41 13-195 Peace River 7545 6579 14124 1 688 4 10 18 12-48 Peace River 5833 5086 10919 1 15 4 0 3 20-215 Arcadia 7293 6358 13651 1 1096 10 15 36 20-143 Arcadia 7429 6477 13906 1 2570 11 36 32 49-154.5 Arcadia 10563 9210 19773 2 2620 3 52 28 5-1-235 Arcadia 7350 6408 13758 1 1468 8 20 17 25-299 Arcadia 9356 8158 17514 2 1734 5 30 28 4-1-501 Arcadia 2839 2475 5314 1 186 5 1 1 5-320 Arcadia 9595 8365 17960 2 34 5 1 24 22-170 Tampa 10190 8883 19073 2 929 31 18 14 3-3-275 Tampa 4892 4265 9157 1 2036 5 19 12 12-529 Nocatee 13805 12036 25841 3 2884 9 75 69

PAGE 88

76 Figure 37A demonstrates the distribu tion of the calcula ted and measured arsenic concentrations in pyr ites. For those samples that lie significantly above the equal concentration line of pyrite, calculated arsenic con centrations are lower than these measured in the bulk sample (Figur e 37A). These results can be explained by existence of other sources of arsenic (cla ys, phosphate and organic material, hydrous ferrous oxides) or underestimation of the po ssible amount of pyrite, or an insufficient number of analyzed pyrite crystals. Sample 49 – 154.5 s hows much higher calculated arsenic concentration compared to a measur ed result probably due to overestimation of pyrite constituent or a insufficient number of analyzed pyrites. Elimination of the outlier data points results in str ong linear correlation, with corresponding R2 value of 0.89 for arsenic calculated versus measured by AFS (Figure 37B). 0 10 20 30 40 50 60 70 80 90 0102030405060708090As (ppm) calculatedAs (ppm) measure d As meas.=As calc. (A)

PAGE 89

77 R2 = 0.890 10 20 30 40 50 60 70 80 01020304050607080As (ppm) calculatedAs (ppm) measured Figure 37. Diagram showing arsenic calcula ted vs. arsenic measured from the Hawthorn Group including all data (A) and ex cluding points from the circle (B); see text for additional information. Mobilization of Arsenic during Phosphate Mining Apatite group minerals are stable under a broad range of geologic conditions for millions of years (Nriagu, 1974; Wri ght 1990). The trace elemental composition of the apatite fossil teeth and bones, a nd analyses of the sedimentary phosphorite deposits by Wright (1990) and others (Kovach and Zartman, 1981; Shaw and Wasserburg, 1985; Keto and Jacobsen, 1987) revealed that biogenic and sedimentary apatite incorporates consider able amounts of radionuclides and metals from seawater. Different elements substitute for calciu m, phosphate, and hydroxide in the apatite crystal structure (Deer et al., 1992; Skinne r, 1989, 2002). Apatite locks these metals (B)

PAGE 90

78 and radionuclides in a crystal structure fo r billions of years with no consequent leaching, exchange, desorption, even due to diagenetic changes in water chemistry, pH, and temperatures. This is because the apat ite mineral structure is very stable in a broad range of environmental conditions, such as pH 2 to 12, temperature as high as 1000 degrees C, in the presence of aque ous and non-aqueous solutions (Shields, 2002). Central Florida has extensive phosphor ite mining facilities for the Miocene Hawthorn Group sediments. The mineable phosphate sources expand through central Florida from Hillsborough and Polk Coun ties south throughout Hardee, Desoto, Manatee, Sarasota, and Char lotte Counties (Blakey, 1973). The Peace River Formation of the Ha wthorn Group contains substantial amounts of phosphate and is currently bei ng exploited for phosphate ore. According to our comprehensive geochemical studies, the Peace River Formation contains the highest concentration of ar senic ( = 9 ppm) compared to the Arcadia Formation, Tampa and Nocatee Members (Table 2). Deta iled mineralogical analyses confirm the presence of ubiquitous pyrite crystals har boring considerable am ounts of arsenic. In addition, EMPA elemental mapping revealed that pyrite crystals are located both inside the francolite matrix with arseni c as high as 3730 ppm (Table 10, Figure 15) and as a minor mineral phase in the sedi ment with varying concentrations. Therefore, even if phosphate minerals are stable in a wide range of environmental conditions, arsenic contam ination of the mineable Peace River Formation can cause several latent problem s for the phosphate industry. First of all,

PAGE 91

79 there have been several incidences of swin e fatalities due to arsenic poisoning as a result of phosphate feed supplements (El Bahri, Romdane, 1991). In addition, oxidation of pyrite in aerobic conditions w ill release significant amounts of sulfate, acidity and naturally occurring ar senic (Smedley and Kinniburgh, 2003). Furthermore, these results could lead to c ontamination of water supplies, pollution of rivers and bays in Florida, hamper the operation of wetlands, affect wildlife and aquatic life, and cause serious health problems, such as leukemia, colon cancer and lung cancer. Mobilization of Arsenic during Aquifer Storage and Recovery (ASR) Recently, ASR facilities in central Florid a reported that arsenic concentrations in recovered water are in excess of 100 g/L (Arthur et al., 2001; Ar thur et al., 2002). The ASR storage zone in the study area is the Suwannee Limestone, which directly underlies the Hawthorn sediments. The mobilization of arsenic from the aquifer is caused by the change in redox conditions via the pumping of oxygen-rich surface water into groundwater that is under reduc ing conditions (Arthur et al., 2002). The arsenic in the Suwannee Limestone probabl y could migrate from the Hawthorn Group deposits through the downward leaching processes (Price, Pichler, 2002). When pyrite is exposed to atmospheric O2 and water at the earth's surface, it reacts to form H+, SO4 2-, and Fe2+ (Evangelou, 1995): FeS2 + 7/2O2 + H2O Fe2+ + 2SO4 2+ 2H+

PAGE 92

80 The Fe2+ formed can be further oxidized into Fe3+, which hydrolyzes into iron hydroxide to discharge extra amount s of acid into the environment: Fe2+ + 1/4O2 + H+ Fe3+ + H2O and Fe3++ 3H2O Fe(OH)3 + 3H+ (Evangelou, 1995) Eh-pH diagram (Figure 38) is used to s how if a particular geologic site is under pyrite oxidizing conditions or pyrite stabilizing conditions (Evangelou, 1995). The diagram clearly demonstrates that Fe(OH)3 is not stable under reducing subsurface environment and pyrite is not st able under oxidizing conditions resulting in release of possible arsenic. Figure 38. Stability diagram of pyrite and Fe(OH)3 in water at 25C and 1 atmosphere total pressure (Modified from Evangelou, 1995) Oxidizing Conditions Reducing Conditions

PAGE 93

81 CHAPTER SIX CONCLUSIONS Our detailed mineralogical and geoc hemical study demonstrates that: (1) Arsenic in the Hawthorn Group varies fr om the formation to formation and is mostly concentrated in tr ace minerals, such as pyrite; (2) Average arsenic concentrations signif icantly change from 9.0 ppm in the Peace River Formation to 3.0 ppm in the Tampa Member of the Arcadia Formation. As concentrations for all Hawthorn samples vary from 0.07 to 69.0 ppm; (3) Pyrite occurs in framboidal and euhedr al forms and is unevenly distributed throughout the Hawthorn Group; (4) Concentrations of the arsenic in pyrite crystals can vary drastically from a minimum of 0 ppm to a maximum of 8260 ppm; (5) Hydrous ferric oxides can cont ain arsenic as high as 540 ppm; (6) Phosphate, organic material, a nd clays contain lower arsenic concentrations than in pyrite; (7) Arsenic, sulfur and iron have l ognormal distribution throughout the Hawthorn Group; (8) Phosphorous, arsenic and sulfur are chem ically closely related; they often occur together in nature, thus posi ng a potential problem for the phosphate industry; (9) Aquifer storage and recovery processe s could cause migration of released arsenic from the Hawthorn Group to the Suwannee Limestone through downward leaching processes, depending on chemical gradient in ground water;

PAGE 94

82 (10) Further investigations should be appl ied to understand the ultimate source of arsenic in Florida deposits. Information about the concentrati on, distribution and mineralogical association of naturally occurring arsenic in the Hawthorn Group is important, because this is a first step to forecas t its behavior during anthropogenic induced physico-chemical changes in the aquifer and to understand its cyc ling in the Florida platform.

PAGE 95

83 REFERENCES Andrews, J.E., Brimblecombe, P., Jickells T.D., Liss, P.S., 1996, An introduction to environmental chemistry, Blackwell Science Ltd., London, pp. 136-138. Arthur, J.D., Dabous A.A., Cowart J.B., 2002, Mobilization of arsenic and other trace elements during aquifer storage and recovery, Southwest Florida, OpenFile Report U. S. Geological Survey, Report: OF 02-0089, pp.47-50. Arthur, J.D., Cowart J.B., Dabous A.A., 2001, Florida aquifer storage and recovery geochemical study; year three progress report, Open File Report Florida Geological Survey, Report: 83, 46 pp. Arthur, J.D., Cowart J.B., Dabous A. A.,2000, Arsenic and uranium mobilization during aquifer storage and recovery in the Floridan Aquifer system, Geological Society of America, vol.32, no.7, pp.356. Bang, B.S., 1994 Framboidal pyrite and a ssociated organic matrices. A risky composite for preservation of foss ils. In: Kejser, U.B. (ed.), Surface Treatment: Cleaning, Stabilization and Coatings. IIC Nordic Group, Danish Section, XIII Congress, Copenhagen, pp 66-82. Baur, W.H., Onishi, B.H., 1969, Arsenic. In: K.H. Wedepohl (Ed.), Handbook of Geochemistry. Springer Verlag, Berlin, A1-33. Belzile, N., Tessier, A., 1990, Interactions between arsenic a nd iron oxyhydroxides in lacustrine sediments, Geochimi ca et Cosmochimica Acta, vol.54, no.1, pp.103-109. Bhattacharya, R., Jana J., DeDalal, S.S. et. al, Groundwater arse nic contamination in the Bengal delta plain; use of geological material, laterite as the remedial option, Memoires des Sciences de la Terre, vol.40, pp.19-22, 2001. Blakey, A.F., 1973, The Florida phosphate indu stry: a history of the development and use of a vital mineral, Harvard University press, Cambridge, 199 pp. Bowell, R.J., 1994, Sorption of arsenic by iron oxides and oxyhydroxides in soils, Applied Geochemistry, vol.9, no.3, pp.279-286.

PAGE 96

84 Brewster-Wingard, G.L., Scott, T.M., Edwards, L.E., Weedman, S.D., Simmons, K.R., 1997, Reinterpretation of the pe ninsular Florida Oligocene; an integrated stratigraphic appro ach, Sedimentary Geology, vol.108, no.1-4, pp.207-228. Chao, T.T., and Theobald, P.K., 1976, The significance of secondary iron and manganese oxides in geochemical e xploration, Economic Geology and the Bulletin of the Society of Economic Geologists, vol.71, no.8, pp.15601569. Chow, L.C., Eanes E.D., 2001, Solubility of calcium phosphates, Monographs in oral science, vol.18, pp. 94-111. Claesson, M., Fagerberg, J., 2003, Arsenic in groundwater of Santiago del Estero, Argentina; sources, mobilization cont rols and remediation with natural materials, Minor field studies, 62pp. Compton, J.S., Mulabisana, J. and McMill an, I. 2002, Origin and age of phosphorite from the Last Glacial Maximum to Holocene transgressive succession off the Orange River, South Af rica, Marine Geology 186, 243-261. Compton, J.S., Donald, H.L., Mallinson, D.J., and Hodell, D.A., 1994. Origin of dolomite in the phosphatic Miocene Hawthorn Group of Florida, J. Sediment. Res., 64: 638–649. Compton, J. S., D. A. Hodell, J. R. Garri do and D. J. Mallinson. 1993. Origin and age of phosphorite from the south-central Florida Platform: Relation of phosphogenesis to sea-level fluctuations and d13C excursions. Geochimica et Cosmochimica Acta 57:131-146. Connor, C.B., Sparks R.S.J., Mason R. M., Bonadonna C., 2003, Exploring links between physical and probabilistic models of volcanic eruptions: the Soufriere Hills Volcano, Monserrat, Geophysical Research Letters vol.30, no.13, 1701. Deer, F.R.S., Howie, R.A., Zussman, J ., 1992, An introduction to the rock-forming minerals, Longman Scientific Technical, Harlow, United Kingdom (GBR). El Bahri, L., Romdane, S.B., 1991, Arseni c poisoning in livestock, Veterinary and Human Toxicology, vol. 33, no. 3, pp. 259-264. Evangelou, V.P. (Bill), 1995, Pyrite oxidati on and its control, CRC Press, Inc., Corporate Blvd., N.W., Boca Raton, Florida.

PAGE 97

85 Evans, M.; Hastings, N.; and Peacock, B. St atistical Distributions, 3rd ed. New York: Wiley, pp. 6-8, 2000. Gao S., Luo, T.-C., Zhang B.-R., Zhang,H.-F., Han, Y.-W., Hu, Y.-K., and Zhao, Z.D, 1998, Chemical composition of the continental crust as revealed by studies in east China. Geochi mica et Cosmochimica Acta 62, 1959–1975. Govindaraju, K., 1994, Compliation of worki ng values and sample description for 383 geostandards. Geostandards Newletter, 18, 1-158. Gilboy, A.E., 1985, Hydrogeology of the Southwest Florida Water Management District, regional Analysis Section Technical Report 85-01. Green, R.C., Arthur J.D., DeWitt D., 1995, Lithostratigraphic and hydrostratigraphic cross sections through Pinellas a nd Hillsborough counties, Southwest Florida, Open File Report Florida Geological Survey, Report: 61, 26 pp. Hinkle, S.R., Polette, D.J., 1999, Arse nic of the Willamette Basin, Oregon, Geochemistry of Arsenic, report 8 (Accessed March, 2003) Hodges, A., Mulkey, D., Philippakos, E., Economic Impact of Florida's Agricultural Chemical and Mining Industries, 2001, Department of Food and Resource Economics, Institute of Food and Agri cultural Sciences, University of Florida, 4pp. Hongshao, Z., Stanforth, R., 2001, Competitiv e adsorption of phosphate and arsenate on goethite, Environ. Sci. and Technol., 35, 4753-4757. Huerta-Diaz, M.A., Morse J. W., 1990, Geoche mistry of trace metals associated with sedimentary pyrite from anoxic marine sediments, Eos, Transactions, American Geophysical Union, vol.71, no.2, pp.98. Jain, C. K. and Ali. I., 2000, Arsenic: occu rrence, toxicity and speciation techniques, Water Research, 34(17), 4304-4312. Jones, S.K. and Owen, R.S., 2001, Regional Water Supply Plan. Southwest Florida Water Management District Report, Brooksville Florida. Kolker, A., Cannon, W. F., Westjohn, D. B ., Woodruff, L. G. 1998, Arsenic-rich pyrite in the Mississippian Marsha ll Sandstone: Source of anomalous arsenic in southeastern Michigan ground water: Geological Society of America, Abstracts with Programs, v. 30, no. 7, p. A-59.

PAGE 98

86 Kolker, A., Goldhaber, M. B., Hatch, J. R ., Meeker, G. P., and Koeppen, R. P., 1999, Arsenic-rich pyrite in coals of the Warrior Field, north western Alabama: Mineralogical evidence for a hydrotherm al origin: Geological Society of America, Abstracts with Programs, v. 31, no. 7, p. A-402. Kazakov, A.V., 1937. The phosphate facies: origin of the phosphorite and the geologic factors of formation of the deposits. Proc. Sci. Inst. Fertilizers and Insectofungicides, 145:1-106. Keto, L.S., Jacobsen S.B., 1987, Nd and Sr isotopic variations of early Paleozoic oceans, Earth and Planetary Science Letters, vol.84, no.1, pp.27-41. Kovach, J., Zartman R.W., 1981, U-Th-Pb dati ng of conodonts, Geological Society of America Abstracts with programs 13:285. Landau, S., Everitt, B.S., 2004, A handbook of statistical analyses using SPSS, Chapman & Hall/CRC Press, 354pp. Lebel, J., Belzile, N., Silverberg, N., Sundby, B., 1983, Geochemistry of arsenic in coastal marine sediments, Eos, Transactions, American Geophysical Union, vol.64, no.45, pp.735. Lepertier, C., 1969, A simplified statisti cal treatment of geochemical data by graphical representation Economic Geology, vol.64, pp.538-550. Li, Y.H., 2000, A compendium of geochemi stry: from solar nebula to the human brain, 55. Princeton University Press, Princeton, 476. Manning, J.A., Goldberg, S., 1997, Adsorption and stability of arsenic (III) at the clay mineral-water interface, Environ. Sci. Technol, vol. 31, pp. 2005-2011. Miller, J.A., 1986, Hydrogeologic framework of the Floridan aquifer system in Florida and in parts of Georgia, So uth Carolina, and Alabama, U. S. Geological Survey Professional Pa per, Report: P 1403-B, pp. B1-B91. Missimer, T.M., 1997, Late Oligocene to Plio cene sea level history of the southern Florida Platform based on sequen ce stratigraphy, Geological Society of America, vol.29, no.3, pp.59. Missimer, T.M., McNeill, D.F., Ginsburg, R. N., Mueller, P.A., Covington, J.M., Scot, T.M., 1994, Cenozoic record of global sea level events in the Hawthorn Group and Tamiami Formation on th e Florida Platform, Geological Society of America, vol.26, no.7, pp.151.

PAGE 99

87 Nickson R.T., McArthur J. M., Ravenscr oft, P., Burgess W. G., Ahmed K.M., 2000, Mechanism of arsenic release to groundwater, Bangladesh and West Bengal, Applied Geochemistry, vol.15, no.4, pp.403-413. Nriagu, 1974, Lead orthophosphates, IV. Format ion and stability in the environment, Geochimica et Cosmochimica Acta 38:887-898. Pichler, T., Arthur, J.D., Price R.E., J ones, G.W., 2004, The arsenic problem during aquifer storage and recovery (ASR), Goldschmidt Conference, Copenhagen, Denmark. Pichler, T., Hendry, J. and Hall, G.E.M., 2001, The Mineralogy of Arsenic in Uranium Mine Tailings at the Rabb it Lake In-pit Facility, Northern Saskatchewan, Canada. Envir onmental Geology, v.40, 4-5, p. 495-506. Price, R.E., Pichler T., 2004, Abundance and mi neralogical associa tion of arsenic in the Suwannee Limestone (Florida): imp lications for arsenic release during water-rock interaction, (in review). Price, R., 2003, Abundance and mineralogica l associations of naturally occurring arsenic in the upper Floridan Aquifer, Suwannee Limestone, University of South Florida, Tampa, Florida, 80 p. Price, R. and Pichler, T., 2002, Naturally occurring arsenic in the Upper Floridan Aquifer, southwest Florida: Implicati ons for aquifer storage and recovery. in Kenny, J. F. (Ed.) GroundWater/Surface Water Interactions, American Water Resources Association, Mi ddleburg, Virginia, TPS-02-2, p. 387392. Pyne, R.D.G., 1994, Groundwater recharge and wells: A guide to Aquifer Storage and Recovery. CRC Press, Inc., 2000 Cor porate Blvd., N.W., Boca Raton, Florida. Riggs, S.R., 1984, Paleoceanographic model of Neogene phosphorite deposition; U.S. Atlantic continental margin, Science, vol.223, no.4632, pp.123-131. Riggs, S.R., 1979, Phosphorite sedimentati on in Florida; a model phosphogenic system, Economic Geology and the Bulle tin of the Society of Economic Geologists, vol.74, no.2, pp.285-314. Schreiber, M.E., Gotkowitz M.B., Simo J.A., Freiberg, P.G., 2003, Mechanism of arsenic release to groundwater from naturally occurring sources, eastern Wisconsin, Kluwer Academic Publishers, Boston, MA, United States.

PAGE 100

88 Scott, T M., 1991, Depositional patterns of the Hawthorn Group in Florida, Geological Society of America, vol.23, no.1, pp.126. Scott, T.M., 1990, The lithostr atigraphy of the Hawthorn Group of peninsular Florida, Open File Report Florida Geological Survey, Report: 36, 12 pp. Scott, T.M., 1989, Florida's phosphorites; deposition to reclamation, Geological Society of America, vol.21, no.3, pp.57. Scott, T.M., 1989, The lithostratigraphy and hydrostratigraphy of the Floridan Aquifer system in Florida, Am. Geophys. Union, Washington, DC, United States. Scott, T.M., 1988, The lithostr atigraphy of the Hawthorn Group (Miocene) of Florida: Florida Geological Survey Bulletin 59, 148 p. Shaw, S.K., 1989, Occurrence, Geochemistry and origin of early diagenetic carbonates of the Hawthorn Group (Mio cene), Marion County, Florida: University of South Florida, Tampa, Florida, 169 p. Shaw, H.F., Wasserburg G.J., 1985, Sm-Nd in marine carbonates and phosphates: implications for Nd isotopes in seaw ater and crustal ages, Geochimica et Cosmochimica Acta, vol.49, no.2, pp.503-518. Shields G., 2002, Phosphorites: a mine of information, Economic Geology Research Unit Newsletter, pp.6-7. Shiryaev, A. N., 1996, Probability, 2nd edition New York: Springer, 621 pp. Sims, K. W. W., Newsom, H. E., and Gladney, E. S.,1990, Chemical fractionation during formation of the Earth’s core and continental crust: clues from As, Sb, W, and M., and In Origin of th e Earth (eds. H. E. Newsom, J. H. Jones, and J. H. Newson). Oxford University Press, Oxford, pp. 291–317. Skinner, H. C. W., 2002, In praise of phospha tes, or why vertebrates chose apatite to mineralize their skeletal elements International Book Series, vol.6, pp.4149. Skinner, H. C. W., 1989, Low temperat ure carbonate phosphate materials or the carbonate-apatite problem; a review, Plenum Press, New York, NY, USA. Smedley, P. L., Kinniburgh, D.C., 2002, A re view of the source, behavior and distribution of arsenic in natural waters, Applied Geochemistry, vol.17, no.5, pp.517-568.

PAGE 101

89 SWFWMD, 2000, Aquifer characteristics wi thin the Southwest Florida Water Management District, Report 99-1, 123 pp. Stow, S.H., 1969, The occurrence of arseni c and the color-causing components in Florida land-pebble phosphate rock, Economic Geology, vol.64, pp.667671. Swan, A.R.H., Sandilands, M., 1995, Introduc tion to geological data analysis, Blackwell Science, United Kingdom, Oxford, 446pp. Taylor, S.R. and McLennan, S.M., 1985, The Continental Crust; Composition and Evolution. Geoscience Texts. Blackwell Scientific Publications, Oxford, 312. Thomas, R.C., Sanders, J.A., 1998, Arseni c coprecipitation in low temperature pyrites: implications for bioremedia tion via sulfate reducing bacteria. Geological Society of America Abst racts with Program, vol. 30, no. 7, pp. A-58. Upchurch, S.B., 1989, Hydrology and chemis try of ground waters in the Central Florida phosphate district, Am. Geop hys. Union, Washington, DC, United States. USGS, 1999, Ground water atlas of the United States Alabama, Florida, Georgia, South Carolina, HA 730-G, Reston, Va.: The Survey, Welch, A. H., Westjohn D.B., Helsel, D. R., Wanty R. B., 2000,Arsenic in ground water of the United States; occurren ce and geochemistry, Ground Water, vol.38, no.4, pp.589-604. Wilkin, R.T., Barnes, H.L., 1997. Formation processes of framboidal pyrite. Geochimica and Cosmochimica Acta, 61 (2), 323-339. Wingard, G.L., Weedman, S.D., McCartan, L ., 1993, Age and diagenesis of Miocene and Oligocene strata of the interm ediate and upper Floridan Aquifer systems in Southwest Florida, Geological Society of America, vol.25, no.6, pp.208. Wright, J., 1990, Conodont apatite: stru cture and geochemistry, p.445-449, 28th International Geological Congress, Pa leontological Society and American Geophysical Union, Washington, D.C.

PAGE 102

90 APPENDICES

PAGE 103

91 APPENDIX A Detailed Lithological Descriptions of the Arcadia Formation Core Samples Sorted by arsenic concentr ations in ascending order

PAGE 104

92Sample Lithological Composition As (ppm) TR-SA-1-55 dolostone;gray ;quartz,phosphate 0.1 12-365 limestone;white gray;quartz,phosphate 0.2 4-1-100 dolostone;gray;phosphate,quartz,pyrite 0.3 12-660 limestone;gray;iron oxides,phosphate,pyrite 0.4 5-1-310 limestone;gray;quartz,phosphate 0.4 4-1-316 dolostone;creamy gray;quartz,phosphate 0.5 20-440 limestone;yellowish gray 0.5 20-90 dolostone;gray to light gray;pyrite 0.6 4-1-350 carbonate-quartz matrix;gray;phosphate 0.6 5-1-285 carb-quartz matrix;gray;phosphate 0.6 12-685 limestone;gray;iron oxides,phosphate,pyrite,quartz 0.8 4-1-275 limestone;white-gray;pho sphate,quartz,iron oxides 0.8 4-1-375 quartz-carb.matrix;gray;phosphate,clay 0.8 5-1-110 dolostone;gray;phosphate,clay,pyrite 0.9 9-480 limestone;light to yellow-gray;iron oxides 0.9 49-225 dolostone;gray 0.9 TR-3-3-475 dolostone;light gray,quartz 0.9 TR-3-3-500 limestone;light gray 0.9 13-370 clay;white;calcite,quartz,phosphate 0.9 20-115 dolostone;light gray;iron oxides 1.0 20-465 limestone;yellowish gray 1.0 12-643 limestone;gray;iron oxides,phosphate,pyrite 1.1 12-380 dolostone;dark gray;pyrite,phosphate,iron oxides 1.1 17-120 dolostone;gray;oxidized pyrite(?) 1.1 TR-3-3-600 limestone;gray;pyrite(?),phosphate 1.1 5-170 dolostone;gray;phosphat e,quartz,iron oxides 1.1 9-455 limestone;light gray 1.2 TRSA-1-255 dolostone;gray; quartz,phosphate,clay 1.2 TR-3-3-650 carbonate-quartz matrix;gray;clay, phosphate 1.2 TRSA-1-355 limestone;creamy gray;qua rtz,phosp.,pyrite,iron oxides 1.2 9-430 carbonate-clay ma trix;light gray 1.3 12-615 limestone;gray;iron oxides,phosphate,pyrite 1.3 12-717 limestone;gray;iron oxides,phosphate,pyrite,quartz 1.3 4-1-425 carb-quartz matrix ;gray;phosphate,clay 1.3 4-1-550 carbonate-clay matr ix;gray;phosphate,quartz 1.3 TR-3-3-575 carbonate-clay matrix;gray;organics 1.4 4-1-501 dolostone;gray;pyrite, iron oxides,quartz,clay 1.5 5-470 limestone;gray;quartz,phosphate,pyrite 1.5 25-290 dolostone;light gray 1.5 4-1-450 limestone;gray;phosphate,quartz,clay 1.5 22-323.5-328.5 pure carbonate sand; gray 1.6 12-390 limestone;gray;phosphate,quartz 1.6 TR-3-3-544 carbonate-clay matr ix;white-green;pyrite(?) 1.7 TR-3-3-611 calcilutite;gray; green clay (algae mats) 1.7 13-545 limestone;gray;quartz,phosphate,iron oxides 1.7 5-705 sandstone;gray;cal cite,pyrite,phosphate 1.7

PAGE 105

93TR-3-3-175 dolostone;gray;oxidized pyrite(?) 1.8 9-380 sand;light gray 1.8 5-445 dolostone;gray;phosphate 1.8 9-405 calcilutite;gray,quartz,phosphate 1.8 5-1-360 carb.-quartz matrix;dark gr ay;pyrite,iron oxides,phosph. 1.9 12-315 limestone;gray;quartz,phosphate 1.9 5-145 carb.-quartz matrix;gra y;phosphate,iron oxides 1.9 5-1-335 limestone;gray;quartz,pyr ite,iron oxides,phosphate 1.9 12-340 limestone;gray;quartz,phosphate 1.9 12-265 limestone;gray;phosphate,clay,quartz 2.0 4-1-475 clay;gray;pyrite,phos phate,quartz,iron oxides 2.0 13-445 limestone;gray;clay,quartz,phosphate 2.0 22-348.5-353.5 carbonate sand; gray;clay 2.1 TR-3-3-678 carbonate-quartz matrix;gray 2.1 5-620 limestone;gray;quartz,phosphate,clay 2.1 25-203 dolostone;olive gray 2.1 13-395 limestone;gray;clay,quartz,phosphate 2.1 49-200 quartz-phosphate sand;light gray;oxidized pyrite(?) 2.1 9-130 dolostone;yellowish gray 2.1 13-470 quartz-carbonate matrix;gray;clay,phosphate 2.1 22-95 calcilutite; light gray 2.2 20-190 dolostone;light gray 2.2 4-1-325 limestone;gray;phosphate,quartz 2.2 13-320 limestone; gray;quartz,phosphate 2.3 39-275 dolostone; gray to yellowish gray 2.3 9-355 carbonate-clay matrix;gray,quartz 2.4 4-1-575 quartz-carb.matrix;gray;quartz,pyrite,phosphate 2.4 22-120 dolostone; gray to li ght gray,clay,phosphate 2.4 4-1-125 carb-quartz matrix ;gray;phosphate,clay 2.4 4-1-150 dolostone;gray;phospate,quartz 2.4 5-1-210 quartz-carb.matrix;white;phosphate;clay 2.4 20-415 limestone;yellowish gray 2.5 TRSA-1-130 carbonate-quartz matr ix;gray,pyrite,phosphate 2.5 4-1-75 dolostone;gray;phosphate,quartz,clay 2.7 13-220 limestone;gray;clay,phosphat e,quartz,pyrite;iron oxides 2.7 20-165 dolostone;gray 2.8 TRSA-1-310 carb.-clay matrix;g ray;quartz,pyrite,phosphate 2.8 TR-3-3-200 carbonate-quartz matrix;gray,phosphate 2.8 13-420 carbonate-quartz matrix;g ray;clay,phosphate,pyrite 2.9 13-520 limestone;gray;clay,quartz,phosphate 3.1 4-1-200 quartz-carb.matrix;gray;p hosph.,pyrite,iron oxides,clay 3.1 5-1-260 carb.-quartz matrix;gre en-gray;pyrite,clay,phosphate 3.1 9-95.5 carb.-clay matr.;gray;pyrite ,iron ox.,phosph,org.(lignite) 3.2 12-215 limestone;gray;phosphat e,pyrite,clay,quartz 3.2 4-1-175 carb-quartz matr ix;gray;clay,phosphate 3.2 4-1-210 quartz-carb.matrix;green-gray;clay,phosphate,pyrite 3.2 13-345 dolostone; gray;quartz,phosphate,clay 3.2 TRSA-1-105 carbonate-quartz matr ix;gray,pyrite,phosphate 3.3

PAGE 106

9412-293 limestone;white gray ;quartz,phosphate,pyrite 3.3 TRSA-1-205 carbonate-clay matrix;gray,quartz,pyrite,phosphate 3.3 TRSA-1-330 quartz-carb.matrix;dark brown;pyrite,pho sphate,clay 3.3 22-70 carb.-quartz matrix; li ght gray,phosphate,clay 3.3 25-265 limestone;yellowish gray 3.3 13-495 limestone;gray;clay,quartz,phosphate 3.4 TR-SA-1-280 sandy clay;d ark gray;phosphate 3.5 4-1-485 clay;dark gr ay;pyrite,phosphate 3.5 5-495 carb.-quartz matrix;dark gray;pyrite,clay,phosphate 3.6 5-195 limestone;gray;phosphate,quartz,iron oxides 3.6 TR-3-3-625 carbonate-quartz matrix;gray,clay, phosphate 3.7 5-595 carb.-quartz matrix;gray; phosphate,pyrite,iron oxides 3.7 12-240 carb.-clay matrix;dark gr ay;phosphate,pyrite,quartz 3.7 TR-3-3-125 carb.-quartz matrix;green-gray,clay,phoshate 3.7 49-117.5 carbonate-clay matrix ;light gray;phosphate 3.9 4-1-225 quartz-carb.matrix;gray;p hosphate,pyrite,iron oxides 4.0 TR-3-3-644 carbonate-clay ma trix;green;iron oxides 4.2 4-1-400 sandstone;dark gray; phosphate,iron oxides,clay 4.2 5-646 limestone;gray;quartz,phosphate,clay,pyrite 4.3 9-505 clay;greenish gray 4.3 5-670 limestone;gray;quartz,pho sphate,clay,iron oxides 4.3 25-313 limestone;light gray;pyrite 4.3 TR-9-2-65 carbonate-quartz matrix;gray;clay 4.4 5-284 carb.-clay matrix;green gr ay,phoshate,pyrite,organics 4.4 TRSA-1-80 carbonate-clay matrix;gray,quartz,pyrite,phosphate 4.4 5-295 carb.-clay matrix,green gray;pyrite,quartz,phosphate 4.6 39-325 dolostone;white to light gray,phosphate 4.6 5-245 quartz-carb.matrix;dar k gray;clay,phosphate 4.8 4-1-514 clay;dark gray;pyrite,iron oxides 4.8 9-155 quartz-carb.matrix; gray; phosphate,clay 4.8 TRSA-1-155 carbonate-clay matrix ;dark gray,pyrite,phosphate 4.8 TRSA-1-180 carbonate-clay matrix ;white-gray,pyrite,phosphate 4.9 25-165 limestone;gray;phosphate 4.9 17-195 dolostone;light greenish gray,clay 4.9 TRSA-1-230 carb.-clay matrix;green -gray,quartz,pyrite,phosphate 4.9 TR-3-3-250 carbonate-quartz matrix;gray,phosphate 4.9 5-395 quartz-carb.matrix;gray;phosphate,clay 5.0 5-270 carb-quartz matrix;gray;pyrite,phosphate 5.1 TRSA-1-305 carb.-clay matrix;green -gray,quartz,pyrite,phosphate 5.3 TR-3-3-450 dolostone;yellowish gray;pyrite(?) 5.3 TR-3-3-525 limestone;light gray;pyrite(?) on organics 5.3 5-345 carb.-quartz matrix;gray;pyrite,clay,phosphate 5.6 39-375(2) dolostone;light gray,phosphate,clay 5.7 25-115 carb.-quartz matrix;g ray;pyrite,phosphate,clay 5.9 17-148 sand;grayish green;organics 5.9 TRSA-1-29 quartz-carb.matrix;gray;pyri te,iron oxides,phosph.,clay 5.9 TR-3-3-99 quartz-carb.matrix;green-gray,clay,phosphate 6.0 39-300 quartz-carb.matrix;li ght gray,clay,phosphate 6.0

PAGE 107

955-695 carb.-quartz matrix;gray;phosphate,clay,pyrite 6.1 5-370 carb.-quartz matrix;g ray;pyrite,phosphate,clay 6.1 5-570 quartz-carb.matrix;gray;phosphate,clay,pyrite 6.2 39-225 dolostone; gray 6.3 4-1-525 clay;gray;pyrite;iron ox ides;phosphate,quartz,calcite 6.4 39-350 carb.-clay matrix;gray,quartz,phosphate 6.7 20-240 clay;greenish gray 6.7 13-295 limestone;dark gray;quartz,phosphate,clay,pyrite 6.7 13-570 carbonte-quartz matrix;green;pyrite,iron oxides 6.9 22-145 calcilutite; light gray 6.9 25-284.5 carbonate-clay matrix;light gray 7.0 39-250 clay;gray to greenish gray 7.1 5-220 carb.-clay matrix,gra y;pyrite,quartz,phosphate 7.2 17-95 limestone;light gray;quartz,clay 7.3 TR-3-3-225 dolostone;yell owish gray,phosphate 7.4 9-105 limestone;grayish olive,phosphate,clay 7.4 9-207 dolomitic sandstone; gray 7.4 4-1-599 limestone;dark gray;phosphate,iron oxides 7.5 TRSA-1-300 carb.-clay matrix;green -gray,quartz,pyrite,phosphate 7.7 49-175 quartz-carbonate matrix;light gray;pyrite,phosphate 8.0 22-73.8 quartz-carb.matrix;light gray,clay 8.0 20-140 dolostone;yellow-gray;phosphate 8.2 25-178.5 carbonate-clay matrix;gray, phosphate 8.3 17-167 carb.-clay matrix;green-gray;pyrite 8.5 TR-3-3-138 clay;green;oxidized pyrite(?) 8.8 TR-3-3-550 carbonate-clay matrix ;gray;oxidized pyrite(?) 8.8 25-140 calcilutite;gray 9.2 5-1-218 clay;gray-gre en;pyrite,quartz 9.3 5-1-135 carb.-quartz matrix;gray;pyrite,clay,phosphate 9.4 17-145 dolostone;gray;iron oxides 9.5 13-245 carbonate-clay matrix;gra y,pyrite,phosphate,quartz 9.6 TR-3-3-150 carb.-quartz matrix;g ray-brown,pyrite,clay,phosphate 9.7 25-215 dolomite-clay matrix ;light gray,pyrite 9.9 49-150 carbonate-clay matrix;greenish gray;organics 9.9 TR-3-3-523.5 clay-carb.matr.;gray-br own,pyrite,quartz,phosphate 10.2 4-1-250 clay;gray;pyrite,calcite,iron oxides 10.3 9-55 carb.-clay matrix;green-g ray,pyrite,phosph.,quartz 10.5 39-375(1) clay;gray;phosphate 11.1 17-170 carb.-clay matrix;green-g ray,quartz,phosphate,pyrite 11.1 TR-3-3-145 clay;green;iron oxi des,quartz,pyrite,phosphate 11.2 9-80 carb.-clay matrix;green-g ray,pyrite,phosph.,quartz 11.4 49-115 carbonate-clay matrix;gre en-gray;pyrite,phosphate 11.7 5-1-160 carb.-clay matrix;gray;quartz ,pyrite,iron oxides,phosph. 11.9 39-200 carb.-clay;yellow-gray ,pyrite,quartz,phosphate 12.1 49-125 carbonate-clay matrix;li ght gray;pyrite,phosphate 12.8 12-190 carb.-clay matrix;gra y;pyrite,quartz,phosphate 14.6 25-190 calcilutite;green-gray;clay,quartz,pyrite,phosphate 15.4 9-530 limestone;light gray;cla y,pyrite,quartz,phosphate 16.5

PAGE 108

96TRSA-1-44.8 clay;gray;pyrite,calcite,phosphate 17.1 5-1-235 carb.-clay matrix;gray;ir on oxides,quartz,pyrite,phosph. 17.2 9-180 quartz-carb.matrix;yello w-gray,pyrite,phosphate 17.9 5-1-187 clay;gray-green; pyrite,iron oxides 18.1 4-1-115 clay;dark gray;pyrite,iron oxides,gypsum,calcite,quartz 18.1 13-270 clay;dark gray,pyrite on gypsum 18.7 5-320 carb.-clay matrix;gra y;pyrite,quartz,phosphate 23.7 5-420 clay;dark gray;pyrite,quar tz,iron oxides,phosphate 25.9 TRSA-1-213 clay;dark gray;pyr ite,gypsum,phosphate 26.2 25-299 clay;dark green-gray;quart z,calcite,pyrite,phosphate 27.9 49-154.5 carbonate-clay matrix;gre en-gray;pyrite,iron oxides 28.5 20-143 dolostone;yellow-gray;pyrite,phosphate 32.3 4-1-111 clay;dark gray ;pyrite,gypsum 33.1 20-215 dolomite-clay matrix ;light gray,pyrite 36.0

PAGE 109

97 APPENDIX B Detailed Lithological Descriptions of th e Tampa Member of the Arcadia Formation Core Samples Sorted by arsenic concentr ations in ascending order

PAGE 110

98Sample Lithological Composition As (ppm) 22-273.5-278.5 pure carbonate sand.;gray 0.2 20-290 limestone;light gray;pyrite(?) 0.2 39-425 sandstone;gr een-gray;clay 0.3 39-400 limestone; light gray 0.3 22-250 carbonate sand;yellowish gray 0.3 20-315 limestone;yellowish gray;pyrite(?) 0.3 39-450 carb.-quartz matrix; light to greenish gray 0.3 TR-3-3-400 limestone;yellow-gray;pyrite(?) 0.3 TR-3-3-404 limestone;light gray;pyrite(?) 0.4 DV-1-139.5 carbonate-quartz matrix;gray;pyrite(?) 0.4 TR-3-3-309.5 limestone;yellow-gray;pyrite(?) 0.4 9-255 limestone;light to yellow-gray;pyrite(?) 0.4 5-1-385 sandstone;gr ay;phosphate,clay 0.4 20-279 limestone;yellowish gray;pyrite(?) 0.4 20-265 carbonate-quartz ma trix;yellowish gray 0.5 49-350 limestone;yellow-gray;pyrite(?) 0.5 TR-3-3-300 limestone;yellow-gray;pyrite(?) 0.5 39-510 limestone; white to yellowish gray 0.5 TR-9-2-140 limestone;yellowish gray 0.6 TRSA-1-380 limestone;white-gray;quartz,phosphate,iron oxides 0.6 49-375 limestone;yelllow-gray ;Tampa/Suwannee contact 0.7 17-245 limestone;light gray;oxidized pyrite(?) 0.8 39-467 limestone; yellowish gray 0.8 9-230 limestone;light to yellow-gray;pyrite(?) 0.9 DV-1-125 limestone;light gray 0.9 22-300 carbonate sandstone; gray 0.9 TR-9-2-190 dolostone;brownish gray 0.9 TRSA-1-405 limestone;white-gray;quartz,phosphate,iron oxides 0.9 TRSA-1-430 limestone;white-gray;quartz,phosphate,iron oxides 0.9 4-1-300 limestone;gray;phosphate,quartz 1.0 TR-9-2-165 dolostone;dark gray 1.1 TR-3-3-325 limestone;light gray;pyrite(?) 1.1 5-1-410 carbonate-quartz matrix;gray;phosphate 1.2 DV-1-106 limestone;yellowish gray 1.3 TRSA-1-455 limestone;white-gray;quartz,phosphate,iron oxides 1.3 TR-9-2-265 limestone;light gray;iron oxides 1.4 39-500 limestone; yellowish gray 1.4 17-270 carbonate-quartz matrix;gray 1.5 TRSA-1-419 quartz-carb.matrix;green-gray;pyrite,phosphate 1.5 9-280 limestone;light to yellow-gray;pyrite(?) 1.5 49-325 limestone;yellow-gray;pyrite(?) 1.6 49-300 cuttings;carb-quartz matrix;gray;iron oxides 1.8 17-220 limestone;light gray;oxidized pyrite(?) 2.1 20-365 limestone;yellowish gray;pyrite(?) 2.2 TR-9-2-115-119 quartz-carbonate matrix; light gray 2.3 TR-3-3-375 limestone;yellow-gray;pyrite(?) 2.3

PAGE 111

995-1-488 limestone;gray;quartz,pyrite;iron oxides 2.4 9-305 limestone;light gray;pyrite(?) 2.4 TRSA-1-480 limestone;white-gray;quartz,phosphate,iron oxides 2.4 TRSA-1-484 limestone;white-gray;quartz,phosphate,iron oxides 2.5 TR-3-3-350 limestone;yellow-gray;pyrite(?) 2.6 49-250 carbonate-quartz matrix;grayish white 2.7 9-330 limestone;light gray 2.9 22-225 calcilutite;gray to white;clay 3.0 TR-3-3-425 dolostone;yellowish gray 3.0 20-390 clay;yellowish gray 3.2 TR-9-2-90 quartz-clay matrix;gray;iron oxides,phosphate 3.8 DV-1-150 quartz-carbonate matrix;gray;clay 3.9 39-390 carbonate-clay ma trix;gray;pyrite(?) 4.3 5-1-436 quartz-carb.matrix;gray;phosphate,clay 4.5 TR-9-2-101.5 sandy clay; gray;oxideized pyrite(?),phosphate 5.2 20-340 quartz-carb.matrix;yellowish gray;pyrite(?) 5.5 5-1-460 dolostone;gray;clay,quartz,pyrite,phosphate 5.6 DV-1-100 limestone;light gray;pyrite(?) 6.8 49-275-280 cuttings;carb.-quartz matrix;gray-green;clay 7.1 TR-9-2-215 carb.-clay matrix;gr een-yellow-gray,quartz,pyrite 8.1 TR-9-2-240 sandy clay;greengray;phosphate,pyrite 8.3 5-1-421 clay;dark brown;pyri te,iron oxides,quartz 10.0 39-475 dolostone;dark gray;pyrite 10.4 22-195 clay; grayish green 12.3 TR-3-3-275 carb.-clay matrix;grayish brown;pyrite,quartz 12.3 22-170 carb.-clay matrix;gr een-gray;pyrite,phosphate 14.0 DV-1-113 limestone;light gray;pyrite,quartz 14.2 9-352.5 clay;gray;pyrite,ir on oxides,feldspar,quartz 15.2

PAGE 112

100 APPENDIX C Detailed Lithological Descriptions of the Nocatee Member of the Arcadia Formation Core Samples Sorted by arsenic concentr ations in ascending order

PAGE 113

101Sample Lithological Composition As (ppm) 13-704 limestone;white gray,quartz,phosphate 0.5 13-690 limestone;gray;quartz,phosphate 0.5 12-462-467 sandstone;white gray,phosphate 0.5 12-545 limestone;gray;pyrite,iron oxides,phosphate,quartz 0.8 12-590 limestone;gray;iron oxides,phosphate,quartz 0.9 12-490 limestone;gray;pyrite,quartz,phosphate,iron oxides 0.9 17-395 limestone;light gray;pyrite 1.0 17-295 limestone;light gray 1.5 12-517 limestone;gray;pyrite,i ron oxides,phosphate 1.5 12-567 limestone;gray;pyrite,iron oxides,phosphate,quartz 1.6 12-454 sandstone;green-gray,phosphate,clay 1.8 12-414-419 quartz-carb.matrix;gray;phosphate,clay 1.9 17-412 limestone;light gray;pyrite 2.0 17-420 limestone;light gray;pyrite 2.6 17-370 dolostone;gray;clay 2.7 13-644 sandstone;green-gray;c lay,phosphate,calcite 3.5 5-520 limestone;gray;quartz,phosphate,clay 3.8 13-627 sandy clay;brown;pyrite,phosphate 5.2 17-320 carb.-quartz matrix;yellow-gray,phosphate 6.5 5-545 limestone;gray;quartz,phosphate,clay 6.6 13-620 sandstone;gray;clay,pyri te,iron oxides,phosphate 7.1 12-440 carb.-quartz matrix ;gray;pyrite,clay 8.2 17-345 quartz-carb.matrix;light gray;pyrite,phosphate 8.8 17-434 carb.-clay matrix;gra y,quartz,pyrite,phosphate 9.9 13-595 clay;gray;pyrite,iron oxides,feldspar,quartz 13.1 13-630 quartz-clay matrix;brown;pyrite,gypsum 13.8 12-529 clay;dark green-gray;pyrite,iron oxides,quartz,calcite 69.0

PAGE 114

102 APPENDIX D Detailed Lithological Descriptions of the Peace River Formation Core Samples Sorted by arsenic concentr ations in ascending order

PAGE 115

103Sample Lithological Composition As (ppm) 13-19 sandy clay;brown gray;phosphate 0.4 39-47.5-52.5 sand;brown 0.4 13-23 clay;green-gray,iron oxides,gypsum,quartz,phosphate 0.4 13-69 quartz-carb.matrix;gray,py rite,clay,ir.ox.,phosphate 0.9 DV-1-6 sand;dark brown 1.1 DV-1-25-26 clay;brownish gray 1.1 13-134 sandstone;gray;clay,phosp hate,pyrite,iron oxides 1.1 12-90 carb.-quartz matrix;g ray;pyrite,phosphate,clay 1.8 20-65 carb.-quartz matrix;grayish green,clay 1.9 12-64.5 limestone;gray;pyrite,phosphate 2.1 12-48 carb.-clay;green-gray,iro n oxides,pyrite,phosphate 2.9 DV-1-48.5-51 clay;brownish gray 3.0 13-108 dolomitic sandstone; gray,pyrite,phosphate 3.2 5-110 clay;dark green-gray ;pyrite,quartz,phosphate 3.2 13-120 quartz-carb.matrix;gra y;clay,phosphate,pyrite 3.3 5-95 clay;green-gray;pyrite,quartz,phosphate 3.8 12-115 carb.-clay matrix;green-g ray;pyrite,phosphate,quartz 3.9 TR-9-2-40 clay;grayish green 4.0 39-125 carbonate matrix;gray,clay,quartz 4.3 25-45-47 sand;gray;clay, phosphate 4.5 22-29 sandy clay; grayish dark green 5.3 39-155 clay-carb.matrix;gray, phosp.,quartz 5.3 4-1-50 sandstone;dark brown;phosphate,iron oxides,clay 5.4 5-85 sandy clay;green-gray ,pyrite,phosphate 5.4 12-41 clay;green-gray;phosphate,iron oxides,pyrite 5.6 39-173-178 sandstone;light bluish gray,clay, phosphate 5.9 39-100 clay;greenish gray 6.1 39-150 clay;dark gray 6.1 12-165 clay;dark gray;phosphat e,quartz,calcite,pyrite 6.2 39-130 clay;greenish gray;iron oxides 6.5 12-125(1) clay;gray-green; pyrite,iron oxides 7.7 12-125(1)dup. clay;gray-gre en;pyrite,iron oxides 8.1 39-72.5-77.5 sand;gray; iron oxides,phosphate 8.1 13-45 carb.-clay matrix;green-gray;quartz,pyrite,phosphate 8.2 13-95 carb.-quartz matrix;gray, pyrite,clay,iron oxides 8.4 13-170 clay;dark gray;pyrite, quartz,calcite,phosphate 8.7 22-45 clay; grayish green 9.3 17-70 clay;greenish gray;iron oxides 9.4 17-50-56 cuttings;limestone;ye llowish gray,phosphate 9.7 20-48.5 sandy clay;green.gray;ir on oxides,pyrite,calc,phosp. 9.8 13-145 quartz-carb.matrix;gray,py rite,clay,iron oxides 10.2 22-20 carb.-clay matrix;grayish green;pyrite,phosp.,quartz 11.2 DV-1-74.5-77 carb.-clay matrix;gra y;iron oxides,pyrite,phosphate 11.4 12-140 carb.-clay matrix;dark gr ay;quartz,pyrite,phosphate 11.8 20-38.5 carb.-quartz matrix;ye llowish gray,clay,phoshate 12.2

PAGE 116

10425-90 calcilutite;gray,clay,quartz,phosphate,pyrite 13.1 TR-3-3-81.5-86.5 cuttings;quartz-carb.m atrix;greenish gray,clay,phosp. 13.9 49-77.3-82.3 phosphate-quartz sand;br own-gray,clay,pyrite,iron ox. 14.9 13-195 carbonate-clay matrix;gray;pyrite 17.7 5-69-74 phosphate-clay matrix; quartz,pyrite,iron oxides 20.0 5-120 carb.-clay matrix;dark gray ;pyrite,quartz,ir.ox.,phosp. 25.1 TR-3-3-56.5-61 cuttings;phos phate-quartz sand;gray 25.8 12-125(2) phosphate matrix;calci te,pyrite,iron oxides,gypsum 26.7 25-65-70 cuttings;carbonate -c lay matrix;gray,quartz 37.2 9-30 clay;dark greenish gr ay,pyrite,phosphate 40.8

PAGE 117

105 APPENDIX E Inductively Coupled Plasma – Optic al Emission Spectrometry (ICP-OES) Results for the Arcadia Formation Samples sorted by well

PAGE 118

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 39-200 257426 9653 73020 456.1 873 9481 52030 12129 12.1 39-225 327946 6204 150678 460.9 1174 5378 34620 7091 6.3 39-250 94756 16924 57569 317.0 1994 9064 21552 25805 7.1 39-275 227056 1782 120381 97.1 981 1481 10488 1990 2.3 39-300 202281 1921 108043 87.0 678 2306 17783 2797 6.0 39-325 240718 1980 123144 101.5 781 2494 22932 3775 4.6 39-350 126856 4239 39542 27.2 499 3474 28271 8354 6.7 39-375(1) 102041 12245 56391 43.5 877 5927 26992 21375 11.1 39-375(2) 246906 2401 125000 50.1 1378 3325 16992 2104 5.7 22-70 261185 2503 121524 35.1 500 3361 10074 1542 3.3 22-73.8 213535 3114 122865 32.9 479 3805 10202 4494 8.0 22-95 202881 2287 129052 61.8 373 1217 4063 3944 2.2 22-120 270696 1386 154402 49.9 302 1282 7360 1419 2.4 22-145 206771 3634 120314 42.9 291 2665 8593 5750 6.9 22-323.5-328.5 185340 3731 2312 27.4 132 465 3412 989 1.6 22-348.5-353.5 256785 4452 6367 32.4 367 720 4527 2234 2.1 9-55 183496 6189 39794 255.7 385 5877 40463 9229 10.5 9-80 228013 3675 116178 101.5 158 4046 9809 5863 11.4 9-95.5 229099 1553 103692 31.5 369 3051 13215 2894 3.2 9-105 265472 1819 83605 46.1 1615 4716 38760 3073 7.4 9-130 253529 1412 141694 51.6 149 1576 3072 2530 2.1 9-155 146037 1971 58632 30.9 401 2275 20232 4066 4.8 9-180 173673 4032 63053 32.6 823 5752 34243 6527 17.9 9-207 255139 3936 132406 39.9 217 2873 5296 4976 7.4 9-355 199642 2330 58164 62.0 298 3217 12428 3129 2.4 9-380 261621 2557 6734 31.6 439 3475 16882 2723 1.8 9-405 195795 3305 13403 32.9 370 3752 17056 5381 1.8 106

PAGE 119

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 9-430 275091 5574 108827 69.5 334 4399 5874 12515 1.3 9-455 479444 1620 6530 28.4 262 2044 9333 1300 1.2 9-480 379619 1305 6317 26.8 153 1351 3757 1210 0.9 9-505 21294 9845 96792 33.7 1719 4458 9209 18418 4.3 9-530 335534 2137 15066 12.6 817 1943 9970 2215 16.5 25-115 211058 1471 110577 53.8 1064 1716 11614 1462 5.9 25-140 204071 2923 103340 98.6 433 3068 10448 4880 9.2 25-165 277924 2628 99869 31.5 2161 3499 38240 3798 4.9 25-178.5 241584 3713 44010 16.8 3523 6386 72456 5941 8.3 25-190 205288 4952 46683 28.4 2238 6250 58068 6154 15.4 25-203 268176 1085 137068 47.1 708 1074 3369 757 2.1 25-215 258654 5769 112981 51.4 748 5288 26413 9808 9.9 25-265 238975 2640 24493 28.6 3335 2399 2823 2938 3.3 25-284.5 188461 5433 40144 20.7 1134 5433 48972 12500 7.0 25-290 326923 716 143269 18.8 658 1591 8787 1091 1.5 25-299 147030 12030 28069 43.6 819 9356 40082 19059 27.9 TR-9-2-65 173267 1802 97030 94.6 784 851 6321 2738 4.4 20-90 239011 577 126923 26.9 405 1181 1387 295 0.6 20-115 278230 1013 144354 76.8 519 1649 5469 757 1.0 20-140 223516 2689 108265 28.5 870 2439 17207 4302 8.2 20-143 309080 7334 142026 66.9 1436 7429 20278 1787 32.3 20-165 233467 1403 128257 26.6 570 1600 2506 1373 2.8 20-190 210922 1693 120240 33.6 1417 1270 1575 1849 2.2 20-215 157315 8267 98196 40.6 1140 7293 6323 9669 36.0 20-240 147796 6563 70641 53.1 905 4407 16159 10571 6.7 20-415 345650 769 7330 4.2 3442 2255 4474 1204 2.5 20-440 443981 353 6973 3.6 235 1193 172 <0.0009 0.5 20-465 360440 388 4346 2.7 2196 879 927 535 1.0 107

PAGE 120

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 17-95 276768 10505 49444 114.1 2223 4743 43311 4480 7.3 17-145 303535 1152 143434 61.1 609 1640 5537 1601 9.5 17-148 211765 2539 114706 40.2 510 2779 6569 3093 5.9 17-167 123529 2529 40049 26.0 935 3144 24259 5294 8.5 17-170 203407 6413 65631 26.1 1093 6716 37061 9068 11.1 17-195 241667 5637 48775 25.0 2221 7030 61471 9657 4.9 TR-3-3-99 245588 1799 117647 22.1 648 2045 3063 1701 6.0 TR-3-3-125 172772 4604 68812 80.2 960 2965 15725 2530 3.7 TR-3-3-138 400835 1931 63152 65.2 252 2572 6716 1508 8.8 TR-3-3-145 8549 16310 24353 60.2 358 10436 2635 20754 11.2 TR-3-3-150 83433 21990 54529 127.5 767 19717 3695 16925 9.7 TR-3-3-175 246699 3397 107443 29.4 884 3917 18750 3037 1.8 TR-3-3-200 238295 1164 129052 22.2 206 1573 2567 858 2.8 TR-3-3-225 193811 1059 85233 48.3 905 1825 16349 1732 7.4 TR-3-3-250 265440 1380 120237 19.1 924 2271 16900 1294 4.9 TR-3-3-450 171669 2251 65426 33.6 1011 2809 19271 2005 5.3 TR-3-3-475 234157 1096 126208 19.9 201 2793 2596 1042 0.9 TR-3-3-500 248657 806 127282 54.2 156 3609 749 2658 0.9 TR-3-3-523.5 296993 1896 25242 28.5 246 3269 7555 2089 10.2 TR-3-3-525 134282 7859 56993 60.0 405 6753 9699 27166 5.3 TR-3-3-544 336333 2672 22666 34.9 1183 2618 1560 4016 1.7 TR-3-3-550 141176 16225 65686 79.9 1211 12228 17179 18529 8.8 TR-3-3-575 135294 6765 53922 35.8 1225 6373 17779 9314 1.4 TR-3-3-600 243147 5012 151371 85.8 4112 3758 6573 7092 1.1 TR-3-3-611 453431 2828 29363 23.5 1279 6176 10897 3505 1.7 TR-3-3-625 116388 7933 111169 55.3 2445 4034 4204 15084 3.7 TR-3-3-644 298039 3309 49510 17.6 2342 2738 4281 4711 4.2 TR-3-3-650 58455 12787 100731 53.8 1275 3799 5858 14248 1.2 108

PAGE 121

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) TR-3-3-678 248352 3044 29121 19.2 1052 2648 14366 5390 2.1 49-115 267582 1544 4846 13.2 572 1564 5429 2247 11.7 49-117.5 220955 2676 123778 200.9 304 2109 7289 5212 3.9 49-125 148481 6355 59055 87.2 526 4281 28155 11136 12.8 49-150 193476 4561 109111 87.2 521 3090 11442 9224 9.9 49-154.5 221805 9560 26423 152.5 916 10563 63668 15789 28.5 49-175 193584 4928 19082 67.5 3126 5944 72306 7799 8.0 49-200 144544 1265 75928 92.8 300 1456 10680 3830 2.1 49-225 232420 781 125745 78.7 868 655 3842 638 0.9 13-220 320833 935 30602 47.7 2708 3222 30093 1255 2.7 13-245 166063 3489 58371 80.5 1869 4706 28824 8597 9.6 13-270 10000 10856 76577 43.2 1856 6937 4068 20631 18.7 13-295 378995 1557 18402 40.6 1041 2292 4840 1954 6.7 13-320 381448 422 2149 5.9 1900 2502 26244 418 2.3 13-345 273756 1796 29276 10.9 2154 1620 6199 6697 3.2 13-370 19801 28756 15025 71.1 657 27662 2194 12239 0.9 13-395 377561 634 30732 8.3 325 1356 3707 1298 2.1 13-420 193243 1221 82883 13.5 1284 2802 11892 2532 2.9 13-445 172059 2510 72059 20.6 463 4284 12451 7353 2.0 13-470 133333 2132 49020 34.3 662 4152 10098 3500 2.1 13-495 372549 956 4824 17.2 966 2348 13284 2103 3.4 13-520 278140 2665 25535 28.8 614 3567 15116 5860 3.1 13-545 172222 1755 55093 13.0 1301 3847 26065 4120 1.7 13-570 325561 438 1857 4.0 420 552 1395 151 6.9 TRSA-1-29 243000 2850 124000 28.0 2135 3225 2400 3825 5.9 TRSA-1-44.8 24163 13846 54299 54.8 2014 6833 7919 21176 17.1 TR-SA-1-55 203182 1032 110909 30.5 1636 1523 2245 1841 0.1 109

PAGE 122

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) TRSA-1-80 131035 4478 25369 68.5 2360 4680 28276 6798 4.4 TRSA-1-130 191031 1175 97309 29.1 857 1511 4529 1166 2.5 TRSA-1-155 195067 1233 104484 31.4 1058 1336 4040 1390 4.8 TRSA-1-180 154751 4077 98190 50.7 1923 1670 2778 6335 4.9 TRSA-1-205 170136 3783 103620 61.1 1977 2439 900 4706 3.3 TRSA-1-213 38670 15813 46946 61.6 2207 8571 5764 20000 26.2 TRSA-1-230 133663 6485 50000 37.6 2257 4901 21386 9505 4.9 TRSA-1-255 217290 2271 113551 39.3 2093 2009 2379 3374 1.2 TR-SA-1-280 68519 9398 59259 82.9 1741 5556 1917 12037 3.5 TRSA-1-300 89604 7871 33762 36.1 2450 7475 20149 12030 7.7 TRSA-1-305 137624 5000 81188 41.6 2054 4564 8564 8465 5.3 TRSA-1-310 940 1614 124651 9.8 4837 3386 1326 3530 2.8 TRSA-1-330 158878 2136 65888 10.3 1734 2944 11729 3206 3.3 TRSA-1-355 305941 258 23119 2.0 594 916 3262 94 1.2 4-1-75 223223 2152 101422 79.6 1066 3308 11232 2204 2.7 4-1-100 241232 407 108531 78.7 886 1763 3934 1005 0.3 4-1-111 10597 19303 23731 145.3 701 18159 2338 22388 33.1 4-1-115 13860 20465 20698 118.1 2140 15349 3005 16930 18.1 4-1-125 238424 1197 125123 20.2 1345 2276 1591 1365 2.4 4-1-150 227442 879 121861 18.6 1512 2242 1940 1060 2.4 4-1-175 200472 1481 91509 48.6 1382 2028 7877 2892 3.2 4-1-200 234259 2597 93056 34.3 2250 4907 20926 1824 3.1 4-1-210 214612 1763 108676 21.9 1242 2342 1333 2128 3.2 4-1-225 177169 2575 91781 28.3 2050 1849 3438 4434 4.0 4-1-250 32277 13119 67327 35.6 2688 5198 3391 23218 10.3 4-1-275 401887 56 3783 1.4 219 410 272 <0.0009 0.8 4-1-316 257870 145 102315 16.2 291 1065 718 16 0.5 4-1-325 319118 471 37941 7.4 417 1363 3873 686 2.2 110

PAGE 123

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 4-1-350 159722 356 82407 11.1 829 968 2185 727 0.6 4-1-375 143981 1847 70833 19.9 1259 2051 10139 3301 0.8 4-1-400 53704 4472 7037 25.9 2356 6852 11759 4435 4.2 4-1-425 171689 1817 78539 35.2 1406 3219 5205 2530 1.3 4-1-450 243056 1569 33009 30.1 1306 2764 6111 1935 1.5 4-1-475 76617 6070 67662 60.2 701 5622 7960 13433 2.0 4-1-485 14406 12426 86634 29.2 772 10050 5644 17525 3.5 4-1-501 162439 3356 104878 53.2 486 2839 4976 5415 1.5 4-1-514 25920 20149 96517 53.2 746 13284 4776 16517 4.8 4-1-525 115423 7761 108955 46.8 647 3080 1846 14129 6.4 4-1-550 109479 5166 55450 27.0 2967 3810 8057 7488 1.3 4-1-575 193981 1972 49537 17.1 2657 1255 1949 3463 2.4 4-1-599 441176 701 2005 4.9 183 1578 359 272 7.5 5-145 205046 794 7110 2.3 537 940 1138 592 1.9 5-170 244811 689 117925 36.3 693 1792 360 774 1.1 5-195 237615 2693 31514 22.9 1023 2688 1294 2280 3.6 5-220 206132 2476 84906 31.1 797 3241 6934 3000 7.2 5-245 103153 4775 18739 60.4 1212 4270 19324 5991 4.8 5-270 299074 1269 1787 63.9 1389 2051 13056 1088 5.1 5-284 136986 7215 73516 158.0 1941 5479 2142 9224 4.4 5-295 127723 6881 7228 156.9 1807 6634 13465 9208 4.6 5-320 96396 11216 66667 78.8 3108 9595 8423 17387 23.7 5-345 310648 1139 51389 31.5 2000 2458 16898 1898 5.6 5-370 247534 1170 39283 93.3 1910 2538 21166 1471 6.1 5-395 159174 2780 41193 51.4 1972 4307 23028 6972 5.0 5-420 8565 12556 78475 48.0 2901 7713 3664 22466 25.9 5-445 252133 536 115640 41.2 455 929 1156 255 1.8 5-470 292202 165 79816 16.1 317 697 844 <0.0009 1.5 111

PAGE 124

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 5-495 235648 1472 104167 15.7 421 2074 6991 2926 3.6 5-570 187963 2417 78704 25.0 1079 3829 6528 3514 6.2 5-595 213426 597 96759 13.4 704 1977 5741 416 3.7 5-620 280660 632 69811 6.6 892 1835 5094 1231 2.1 5-646 292924 835 18632 10.8 1080 2047 7170 1542 4.3 5-670 294495 1257 23165 11.9 1101 2564 8761 2697 4.3 5-695 163014 1516 14338 2.3 918 1475 3795 3662 6.1 5-705 173636 809 85455 17.3 891 1318 923 1382 1.7 5-1-110 245098 451 126471 28.9 442 1691 1034 667 0.9 5-1-135 174074 2519 88889 69.9 1032 2829 8657 3912 9.4 5-1-160 199526 4787 97156 36.0 1645 4559 13744 7678 11.9 5-1-187 10139 16806 38889 53.2 258 7731 2810 22407 18.1 5-1-210 205000 2965 99000 31.0 1560 1940 8950 4735 2.4 5-1-218 14834 16872 44455 46.4 2313 7725 3910 26398 9.3 5-1-235 161000 8950 97000 48.5 2245 7350 8550 12800 17.2 5-1-260 195455 3159 99545 40.5 1845 3432 4591 5227 3.1 5-1-285 207009 172 343 3.7 194 682 2556 214 0.6 5-1-310 416500 247 2580 5.0 455 685 300 142 0.4 5-1-335 261395 329 0 1.4 902 1009 8698 160 1.9 5-1-360 206481 519 1597 1.9 630 769 2648 625 1.9 12-190 153704 6620 58333 66.7 437 6204 22361 15694 14.6 12-215 289352 1069 54167 42.1 2546 2065 9398 1648 3.2 12-240 206393 1845 73059 75.8 2269 3005 14932 5023 3.7 12-265 241509 972 18538 11.8 1858 1792 10330 2783 2.0 12-293 338389 640 68720 46.0 1313 1057 1062 431 3.3 12-315 368519 171 11111 21.8 690 843 1875 58 1.9 12-340 253554 701 85308 8.5 1687 1938 10427 1085 1.9 12-365 378199 163 12607 7.1 343 701 2218 <0.0009 0.2 112

PAGE 125

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 12-380 243137 362 106373 8.8 618 1721 6471 53 1.1 12-390 366667 390 3958 3.2 866 1361 8194 537 1.6 12-590 386500 324 <0.0001 0.5 241 321 865 <0.0009 0.9 12-615 308072 753 64 3.6 619 380 1009 516 1.3 12-643 314545 301 <0.0001 <0.00003305 402 2986 75 1.1 113

PAGE 126

114 APPENDIX F Inductively Coupled Plasma – Optic al Emission Spectrometry (ICP-OES) Results for the Tampa Member of the Arcadia Formation Samples sorted by well

PAGE 127

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 39-390 85392 2583 38185 21.5 460 1737 9890 8700 4.3 39-400 145421 155 <0.0001 2.5 71 244 759 <0.0009 0.3 39-425 57692 313 25440 2.7 988 319 121 1143 0.3 39-450 190118 405 1595 4.8 640 337 675 1300 0.3 39-467 374255 445 1484 10.1 584 378 2895 <0.0009 0.8 39-475 230689 497 114823 34.4 616 1083 945 435 10.4 39-500 448153 852 822 28.0 562 716 19 35 1.4 39-510 379332 117 267 8.7 135 426 23 <0.0009 0.5 22-170 104595 11729 51088 58.6 498 10190 25778 18984 14.0 22-195 32302 15038 71661 60.8 997 5865 4462 24756 12.3 22-225 208585 5429 109432 41.1 965 2165 1711 8283 3.0 22-250 261104 630 92 3.6 236 331 4382 930 0.3 22-273.5-278.5 73897 2193 <0.0001 9.5 145 232 3175 530 0.2 22-300 298292 1110 3647 5.9 213 737 2399 1938 0.9 9-230 441354 647 24244 6.0 228 741 5052 80 0.9 9-255 397124 341 8020 5.5 122 828 3568 131 0.4 9-280 403265 834 13906 9.7 259 1146 5763 <0.0009 1.5 9-305 379106 1163 5138 11.2 247 1441 5896 157 2.4 9-330 354796 1472 8476 14.5 251 1620 5016 194 2.9 9-352.5 72029 11465 7083 61.2 373 11783 13691 30732 15.2 TR-9-2-90 41337 4193 9059 9.9 563 1168 16495 7475 3.8 TR-9-2-101.5 48516 4912 6703 18.1 700 1753 10759 10879 5.2 TR-9-2-115-119 153846 10048 1644 85.1 1045 587 9815 1394 2.3 TR-9-2-140 386634 772 5990 20.8 824 530 2169 1441 0.6 TR-9-2-165 214286 241 124176 103.3 550 717 280 255 1.1 TR-9-2-190 236591 745 131704 57.8 660 900 1875 632 0.9 TR-9-2-215 174613 2652 95352 76.9 4200 1665 3326 4195 8.1 TR-9-2-240 14257 2342 18119 5.0 658 1847 4250 8069 8.3 TR-9-2-265 487745 691 931 32.4 824 956 39 382 1.4 115

PAGE 128

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 20-265 212425 332 368 1.5 968 551 10304 424 0.5 20-279 373063 564 2974 6.0 952 973 2773 <0.0009 0.4 20-290 282565 240 2074 0.5 863 530 2049 28 0.2 20-315 265842 369 2050 0.0 388 668 2718 363 0.3 20-340 298039 1314 4191 12.7 652 1657 6257 1789 5.5 20-365 446154 500 6779 3.4 346 1966 3289 611 2.2 20-390 697259 989 10906 13.7 1459 2569 2636 <0.0009 3.2 17-220 358823 760 3956 7.4 1529 1877 19656 515 2.1 17-245 262255 430 14902 3.4 739 1045 10044 672 0.8 17-270 232353 468 1603 2.0 1171 1213 12239 89 1.5 DV-1-100 384343 1323 13485 138.9 574 807 883 241 6.8 DV-1-106 275000 2255 1216 46.6 1241 604 264 1642 1.3 DV-1-113 302525 2475 732 66.2 756 1680 306 662 14.2 DV-1-125 393434 279 763 23.7 319 314 219 <0.0009 0.9 DV-1-139.5 204993 567 <0.0001 15.8 567 375 30 <0.0009 0.4 DV-1-150 188889 2712 2773 27.3 1878 1044 56 2126 3.9 TR-3-3-275 153806 7091 86548 38.6 470 4892 13038 10010 12.3 TR-3-3-300 392576 345 10967 1.7 199 719 4986 675 0.5 TR-3-3-309.5 414604 251 3224 3.1 79 554 1677 <0.0009 0.4 TR-3-3-325 436518 792 3821 4.2 427 1215 7281 262 1.1 TR-3-3-350 490384 837 8462 13.0 554 1548 7965 314 2.6 TR-3-3-375 358830 900 9055 17.4 325 1486 6262 799 2.3 TR-3-3-400 410011 247 6299 2.2 119 755 2795 <0.0009 0.3 TR-3-3-404 483909 703 5906 8.3 124 826 2636 <0.0009 0.4 TR-3-3-425 233516 566 115385 16.5 614 1483 2848 479 3.0 49-250 230727 471 5863 27.7 899 422 90 1243 2.7 49-275-280 106874 1966 10150 10.2 378 1309 996 5306 7.1 49-300 204410 1710 101311 98.9 882 747 2112 1335 1.8 49-325 356748 625 3252 13.3 226 822 454 1338 1.6 116

PAGE 129

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm)As (ppm) 49-350 415073 154 1108 7.3 288 236 40 <0.0009 0.5 49-357 19624 2463 4071 2.6 569 1409 19 8142 2.3 49-375 456731 112 505 10.6 296 731 48 <0.0009 0.7 TRSA-1-380 372093 127 1144 0.5 382 464 516 <0.0009 0.6 TRSA-1-405 378995 189 2434 4.6 401 466 303 <0.0009 0.9 TRSA-1-419 167488 990 1355 2.5 2507 1005 901 3488 1.5 TRSA-1-430 344500 414 675 6.5 1065 790 3040 1195 0.9 TRSA-1-455 297525 748 3896 16.3 1817 787 4386 3312 1.3 TRSA-1-480 396040 851 4490 10.9 220 604 530 921 2.4 TRSA-1-484 351598 735 3968 11.0 218 571 344 1059 2.5 4-1-300 250000 389 3723 1.5 302 520 3272 718 1.0 5-1-385 57727 686 1218 0.0 1332 664 3859 2527 0.4 5-1-410 206818 274 2745 4.5 389 723 3609 289 1.2 5-1-421 25682 7591 14409 21.4 2768 6364 8409 12636 10.0 5-1-436 121818 2086 52273 42.7 1168 3059 8409 6045 4.5 5-1-460 200976 2839 104878 42.4 1732 4141 1507 5268 5.6 5-1-488 384475 183 562 1.8 152 1484 53 16 2.4 117

PAGE 130

118 APPENDIX G Inductively Coupled Plasma – Optic al Emission Spectrometry (ICP-OES) Results for the Nocatee Member of the Arcadia Formation Samples sorted by well

PAGE 131

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 17-295 266176 975 11667 4.9 668 1208 10044 2382 1.5 17-320 191884 1408 38627 16.0 743 2335 11183 997 6.5 17-345 289290 2293 3917 15.1 1640 3383 26072 1560 8.8 17-370 119907 4086 31665 23.3 938 3635 21495 8149 2.7 17-395 376601 319 5239 7.0 393 753 4728 308 1.0 17-412 380675 594 59953 12.8 692 1112 8227 600 2.0 17-420 399301 675 8382 8.1 550 938 6083 931 2.6 17-434 274738 2526 30675 11.6 760 1681 7880 4348 9.9 13-595 3151 16732 50732 53.2 434 6634 2444 27707 13.1 13-620 30180 8559 24054 95.5 2239 7748 2514 8243 7.1 13-627 34459 11847 12477 81.5 2275 10315 8559 10676 5.2 13-630 9318 12091 2668 37.7 2373 11500 4305 6909 13.8 13-644 40556 4815 16435 42.1 425 4611 4722 5000 3.5 13-690 384091 288 2659 3.6 258 673 923 <0.0009 0.5 13-704 479311 41 3562 3.0 118 452 140 <0.0009 0.5 5-520 311574 1093 37824 12.5 764 1944 4861 1435 3.8 5-545 323697 1464 8152 10.0 1000 2626 8152 2246 6.6 12-414-419 127602 4339 14751 33.0 525 1032 6878 2294 1.9 12-440 211111 1213 2227 13.0 1310 1421 217 2384 8.2 12-454 <0.00002 1441 <0.0001 <0.00003 1417 1607 10 1754 1.8 12-462-467 18900 555 <0.0001 <0.00003 900 227 335 650 0.5 12-490 356621 258 1269 3.2 203 321 195 <0.0009 0.9 12-517 278704 247 <0.0001 <0.00003 481 532 921 <0.0009 1.5 12-529 345320 92 <0.0001 <0.00003 194 382 1325 <0.0009 69.0 12-545 349537 161 <0.0001 <0.00003 254 284 1611 <0.0009 0.8 12-567 386500 324 0 0.5 241 321 865 <0.0009 1.6 12-590 266176 975 11667 4.9 668 1208 10044 <0.0009 0.9 119

PAGE 132

120 APPENDIX H Inductively Coupled Plasma – Optic al Emission Spectrometry (ICP-OES) Results for the Peace River Formation Samples sorted by well

PAGE 133

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 39-47.5-52.5 <0.00002 264 <0.0001 2.5 133 55 326 761 0.4 39-72.5-77.5 42920 2284 <0.0001 44.8 851 1713 17667 2019 8.1 39-100 28872 12223 20962 84.6 347 4814 8117 19635 6.1 39-125 116704 4712 61947 148.8 308 3800 9277 8131 4.3 39-130 52157 15487 16759 99.6 383 11014 6760 19303 6.5 39-150 82302 14666 56559 259.9 652 10390 7504 21844 6.1 39-155 80199 8075 22954 140.5 347 6876 15143 14436 5.3 39-173-178 58628 3258 1892 55.9 623 3065 20941 3512 5.9 22-20 168057 14362 2187 85.2 2376 1825 55029 12217 11.2 22-29 22989 9004 5216 28.2 449 487 8036 11465 5.3 22-45 155462 11164 90636 184.9 416 6815 8929 14106 9.3 9-30 45277 17101 10695 30.4 242 4479 12602 23236 40.8 25-45-47 59901 1520 <0.0001 14.9 1347 1292 22199 4550 4.5 25-65-70 220330 15330 48352 97.3 1645 11597 48881 13462 37.2 25-90 268317 7178 97030 106.4 1503 7327 41624 9307 13.1 TR-9-2-40 39167 12500 44510 98.5 2892 6275 7404 18873 4.0 20-38.5 206198 5822 15018 47.1 3583 5632 60253 3033 12.2 20-48.5 16834 16283 13377 37.6 894 13379 4801 12826 9.8 20-65 250873 2509 140861 50.6 666 2466 1842 1857 1.9 17-50-56 353922 6176 27941 209.8 1407 4142 29614 4382 9.7 17-70 148529 13088 40882 455.4 859 9901 34632 13824 9.4 DV-1-6 <0.00002 8 <0.0001 <0.00003 56 103 161 1414 1.3 DV-1-25-26 66162 1889 <0.0001 27.3 954 200 50000 46212 1.1 DV-1-48.5-51 92929 10606 30455 127.3 1228 1080 22149 16061 3.0 DV-1-74.5-77 118182 8737 34899 123.7 898 1589 20778 14596 11.4 TR-3-3-56.5-61 121086 5376 13413 64.2 1986 5213 34453 2056 25.8 TR-3-3-81.5-86.5 187289 5304 61867 75.9 910 5059 23509 4235 13.9 49-77.3-82.3 85396 5365 8911 131.8 830 4292 25338 5662 14.9 13-19 12537 2605 <0.0001 1.5 507 590 5561 10634 0.4 121

PAGE 134

Sample Ca (ppm) Fe (ppm) Mg (ppm) Mn (ppm) Si (ppm) S (ppm) P (ppm) Al (ppm) As (ppm) 13-23 25248 11584 5644 18.8 2361 1629 8465 13366 0.4 13-45 180930 11395 23116 45.6 488 8465 4130 12093 8.2 13-69 180556 2778 101389 68.1 340 1421 852 4384 0.9 13-95 207407 2644 100926 19.9 1014 3556 755 1935 8.4 13-108 233659 883 118049 14.6 247 2127 737 756 3.2 13-120 171759 2898 81944 29.6 348 4106 2139 4120 3.3 13-134 25099 3040 7822 20.8 435 3327 3891 4272 1.1 13-145 167123 2904 49772 61.6 1187 5160 19909 3740 10.2 13-170 95434 9498 17991 125.6 498 9954 21781 16164 8.7 13-195 185455 6182 89545 78.2 1577 7545 12727 7636 17.7 4-1-50 46364 4441 <0.0001 21.4 1405 4291 16318 4091 5.4 5-69-74 317561 9171 16976 25.9 2180 12000 52195 8585 20.0 5-85 76852 10185 10741 24.1 3204 10324 4347 11944 5.4 5-95 82938 12559 14313 28.0 3043 14929 5782 13223 3.8 5-110 69159 7944 6168 24.8 2047 8364 14019 9533 3.2 5-120 260550 8578 10550 24.3 1904 9495 33761 10000 25.1 12-41 36864 19364 16727 40.5 3355 15364 3323 15500 5.6 12-48 206019 7593 10000 38.0 3454 5833 1755 8565 2.9 12-64.5 377251 2564 5735 3.8 468 3370 383 133 2.1 12-90 208057 1640 106635 19.4 1858 1972 1019 1649 1.8 12-115 89450 7202 45000 65.1 2271 7431 2743 8486 3.9 12-125(1) 55721 23483 40149 167.7 557 24279 4836 20149 7.7 12-125(2) 161692 104975 9254 140.8 2209 120398 52736 5970 26.7 12-125(1)dup 56098 20976 43268 173.7 416 20585 4927 20585 8.1 12-140 106849 12694 47032 206.4 3169 12192 10091 14795 11.8 12-165 119444 7963 23611 263.0 1750 6806 27778 17639 6.2 122

PAGE 135

123 APPENDIX I Electron –Probe Microanalysis of Pyrites Sorted by Formation/Member of the Hawthorn Group

PAGE 136

Sa mple Hawthorn Unit S (wt.%) As (wt.%) Fe (wt.%) Pb (wt.%) Cu (wt.%) Zn (wt.%) Total (wt.%) 12-125-1 Peace R. 53.134 0 45.888 0 0 0.006 99.028 12-125-2 Peace R. 53.47 0.024 46.549 0 0 0.015 100.058 12-125-3 Peace R. 53.024 0 45.456 0 0 0.011 98.491 12-125-4 Peace R. 53.694 0 46.06 0 0 0.004 99.758 12-125-2-1 Peace R. 53. 775 0.005 46.183 0 0 0.01 99.973 12-125-2-2 Peace R. 53.227 0 45.851 0 0 0.002 99.08 12-125-2-3 Peace R. 53.394 0.002 46.297 0 0 0 99.693 13-195-1 Peace R. 35.866 0.027 34.764 0 0 0.145 70.802 13-195-2 Peace R. 15.111 0.048 16.268 0 0 0.132 31.559 13-195-3 Peace R. 47.443 0.063 46.297 0 0 0.034 93.837 13-195-4 Peace R. 27.88 0.137 32.178 0 0 0.172 60.367 12-48map-1 Peace R. 18.309 0 43.709 0 0 0.021 62.039 12-48map-2 Peace R. 23.855 0 40.263 0 0 0.052 64.17 12-48map-3 Peace R. 9.985 0.006 40.87 0 0 0.028 50.889 12-48map-4 Peace R. 17.89 0 36.716 0 0 0.014 54.62 9-30-1 Peace R. 50.578 0.164 45.262 0 0 0.042 96.046 9-30-2-1 Peace R. 52.51 0.163 45.018 0 0 0.002 97.693 9-30-2-2 Peace R. 51.628 0 43.07 0 0 0.031 94.729 9-30-2-3 Peace R. 46.517 0.411 43.619 0 0 0.047 90.594 9-30-2-4 Peace R. 49.517 0.078 44.921 0 0 0.012 94.528 9-30-2-5 Peace R. 27.039 0.128 42.084 0 0 0.002 69.253 9-30-2-6 Peace R. 26.388 0.06 36.802 0 0 0.044 63.294 9-30-2-7 Peace R. 46.048 0.416 44.74 0 0 0.019 91.223 9-30-2-11 Peace R. 47. 727 0.099 45.704 0 0 0.026 93.556 9-30-2-12 Peace R. 48.094 0 46.465 0 0 0.008 94.567 9-30-2-13 Peace R. 52. 692 0.071 45.56 0 0 0.025 98.348 9-30-2-14 Peace R. 48. 036 0.2 43.442 0 0 0.014 91.692 9-30-2-15 Peace R. 41.469 0.082 48.093 0 0 0.03 89.674 124

PAGE 137

Sa mple Hawthorn Unit S (wt.%) As (wt.%) Fe (wt.%) Pb (wt.%) Cu (wt.%) Zn (wt.%) Total (wt.%) 9-30-2-16 Peace R. 47. 299 0.06 42.145 0 0 0.037 89.541 9-30-2-17 Peace R. 46. 969 0.073 45.197 0 0 0.031 92.27 4-1-111-3 Arcadia F. 28.151 0.082 39.712 0 0 0.007 67.952 20-143-1 Arcadia F. 49.175 0.448 44.283 0 0 0.017 93.923 20-143-2 Arcadia F. 49.55 0.412 43.537 0 0 0.014 93.513 20-143-3 Arcadia F. 51.748 0.826 44.184 0 0 0.016 96.774 20-143-4 Arcadia F. 52.838 0.346 43.994 0 0 0.015 97.193 20-143-5 Arcadia F. 53.163 0.228 44.501 0 0 0.03 97.922 20-143-6 Arcadia F. 52.693 0.261 44.937 0 0 0 97.891 20-143-7 Arcadia F. 52.417 0.016 45.644 0 0 0.029 98.106 20-143-8 Arcadia F. 35.261 0.079 42.171 0 0 0.098 77.609 20-143-9 Arcadia F. 40.587 0.067 39.415 0 0 0.018 80.087 20-143-10 Arcadia F. 51.318 0.024 46.282 0 0 0.001 97.625 20-143-11 Arcadia F. 53.397 0.12 46.181 0 0 0.005 99.703 49-154.5-1 Arcadia F. 49.523 0.244 39.691 0 0 0.172 89.63 49-154.5-2 Arcadia F. 51.195 0.382 43.216 0 0 0.28 95.073 49-154.5-3 Arcadia F. 51.564 0.16 43.944 0 0 0.208 95.876 4-1-501-1 Arcadia F. 34.333 0.046 35.593 0 0 0.045 70.017 4-1-501-2 Arcadia F. 33.371 0 39.865 0 0 0.052 73.288 4-1-501-3 Arcadia F. 41.008 0 43.05 0 0 0.057 84.115 4-1-501-4 Arcadia F. 38.601 0.047 48.143 0 0 0.015 86.806 4-1-501-5 Arcadia F. 35.618 0 45.718 0 0 0.032 81.368 5-1-235-1 Arcadia F. 40.059 0.154 42.642 0 0 0.059 82.914 5-1-235-2 Arcadia F. 41.397 0.081 44.876 0 0 0.056 86.41 5-1-235-3 Arcadia F. 39.732 0.151 45.49 0 0 0.067 85.44 5-1-235-4 Arcadia F. 40.444 0.124 46.162 0 0 0.067 86.797 5-1-235-5 Arcadia F. 49.319 0.141 40.762 0 0 0.024 90.246 5-1-235map-1 Arcadia F. 51.21 0.026 44.568 0 0 0.029 95.833 5-1-235map-2 Arcadia F. 47.177 0.124 41.479 0 0 0.014 88.794 125

PAGE 138

Sa mple Hawthorn Unit S (wt.%) As (wt.%) Fe (wt.%) Pb (wt.%) Cu (wt.%) Zn (wt.%) Total (wt.%) 5-1-235map-3 Arcadia F. 45.732 0.373 41.723 0 0 0.027 87.855 5-320-2 Arcadia F. 54.977 0 44.838 0 0 0.037 99.852 5-320-3 Arcadia F. 53.836 0 45.275 0 0 0.018 99.129 5-320-4 Arcadia F. 52. 994 0.007 45.277 0 0 0.009 98.287 5-320-5 Arcadia F. 53. 378 0.01 45.111 0 0 0.016 98.515 25-299-2 Arcadia F. 43.211 0.254 37.304 0 0 0.091 80.86 25-299-3 Arcadia F. 50.562 0.221 40.733 0 0 0.044 91.56 25-299-4 Arcadia F. 46.154 0.028 43.031 0 0 0.068 89.281 25-299-5 Arcadia F. 45.503 0.054 43.396 0 0 0.07 89.023 20-215-1 Arcadia F. 41.059 0.065 36.259 0 0 0.041 77.424 20-215-2 Arcadia F. 44.65 0.112 39.014 0 0 0.058 83.834 20-215-3 Arcadia F. 35.645 0.209 40.982 0 0 0.13 76.966 20-215-4 Arcadia F. 37.568 0.124 43.779 0 0 0.075 81.546 20-215-5 Arcadia F. 51.615 0.059 43.654 0 0 0.052 95.38 20-215-6 Arcadia F. 47.05 0.154 37.511 0 0 0.083 84.798 20-215-7 Arcadia F. 47.505 0.166 39.077 0 0 0.08 86.828 20-215-8 Arcadia F. 21.463 0.148 40.561 0 0 0.068 62.24 20-215-9 Arcadia F. 40.9 0.059 41.971 0 0 0.056 82.986 20-215-10 Arcadia F. 50.113 0 44.057 0 0 0.033 94.203 20-215-11 Arcadia F. 35.899 0.266 34.3 0 0 0.083 70.548 3-3-275-1 Tampa M. 34.098 0.17 46.564 0 0 0.194 81.026 3-3-275-2 Tampa M. 35.866 0.111 47.027 0 0 0.177 83.181 3-3-275-3 Tampa M. 35.402 0.144 46.575 0 0 0.181 82.302 3-3-275-4 Tampa M. 40.622 0.322 46.135 0 0 0.035 87.114 3-3-275-5 Tampa M. 40.697 0.271 46.528 0 0 0.035 87.531 DV-1-113-1 Tampa M. 52.879 0 45.286 0 0 0.021 98.186 DV-1-113-2 Tampa M. 52.799 0.017 45.586 0 0 0.02 98.422 DV-1-113-3 Tampa M. 51.681 0 44.432 0 0 0.019 96.132 22-170-1 Tampa M. 36.444 0.083 44.629 0 0 0.09 81.246 126

PAGE 139

Sa mple Hawthorn Unit S (wt.%) As (wt.%) Fe (wt.%) Pb (wt.%) Cu (wt.%) Zn (wt.%) Total (wt.%) 22-170-2 Tampa M. 37.22 0.105 43.399 0 0 0.029 80.753 22-170-3 Tampa M. 48.8 0.001 43.915 0 0 0.075 92.791 22-170-5 Tampa M. 49.712 0.015 42.956 0 0 0.038 92.721 22-170-6 Tampa M. 25.307 0.207 47.414 0 0 0.117 73.045 22-170-7 Tampa M. 19.282 0.218 48.069 0 0 0.251 67.82 22-170-8 Tampa M. 32.888 0.092 45.315 0 0 0.202 78.497 22-170-9 Tampa M. 17.138 0.149 49.456 0 0 0.184 66.927 22-170-10 Tampa M. 27.52 0.135 45.406 0 0 0.218 73.279 22-170-11 Tampa M. 48.593 0.036 42.909 0 0 0.001 91.539 22-170-12 Tampa M. 49.081 0.109 39.947 0 0 0.064 89.201 22-170-13 Tampa M. 48.77 0.117 39.931 0 0 0.071 88.889 22-170-14 Tampa M. 41.516 0.054 45.434 0 0 0.034 87.038 22-170-15 Tampa M. 43.637 0.057 45.853 0 0 0.042 89.589 22-170-16 Tampa M. 51.398 0.085 41.672 0 0 0.028 93.183 22-170-17 Tampa M. 51.768 0.116 41.715 0 0 0.07 93.669 22-170-18 Tampa M. 51.977 0.002 44.852 0 0 0.082 96.913 22-170-19 Tampa M. 39.34 0.107 46.424 0 0 0.061 85.932 22-170-20 Tampa M. 39.826 0.09 45.994 0 0 0.035 85.945 22-170-21 Tampa M. 38.955 0.06 43.708 0 0 0.076 82.799 22-170-22 Tampa M. 50.903 0.018 44.354 0 0 0.047 95.322 22-170-23 Tampa M. 14.196 0.154 50.962 0 0 0.121 65.433 22-170-24 Tampa M. 47.987 0.012 44.931 0 0 0.025 92.955 22-170-25 Tampa M. 50.436 0.049 44.467 0 0 0.016 94.968 22-170-26 Tampa M. 26.583 0.136 46.548 0 0 0.094 73.361 22-170-27 Tampa M. 51.394 0.053 43.982 0 0 0.388 95.817 22-170-28 Tampa M. 50.041 0.003 43.948 0 0 0.027 94.019 22-170-29 Tampa M. 39.067 0.131 44.698 0 0 0.047 83.943 22-170-30 Tampa M. 30.558 0.139 46.681 0 0 0.146 77.524 22-170-31 Tampa M. 46.109 0.17 37.962 0 0 0.118 84.359 127

PAGE 140

Sa mple Hawthorn Unit S (wt.%) As (wt.%) Fe (wt.%) Pb (wt.%) Cu (wt.%) Zn (wt.%) Total (wt.%) 12-529-3 Nocatee M. 38.617 0.056 34.056 78.055 12-529-4 Nocatee M. 33.399 0.064 36.169 74.56 12-529-5 Nocatee M. 53.059 0.571 45.144 0 0 0.028 98.802 12-529-7 Nocatee M. 52.98 0.42 44.963 0 0 0.036 98.399 12-529-8 Nocatee M. 51.97 0.391 44.142 0 0 0.03 96.533 12-529-9 Nocatee M. 51.523 0.102 45.126 0 0 0.019 96.77 12-529-10 Nocatee M. 52.759 0.483 44.616 0 0 0.022 97.88 12-529-11 Nocatee M. 33.705 0.273 33.781 0 0 0.023 67.782 128


xml version 1.0 encoding UTF-8 standalone no
record xmlns http:www.loc.govMARC21slim xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.loc.govstandardsmarcxmlschemaMARC21slim.xsd
leader nam Ka
controlfield tag 001 001498125
003 fts
006 m||||e|||d||||||||
007 cr mnu|||uuuuu
008 041209s2004 flua sbm s000|0 eng d
datafield ind1 8 ind2 024
subfield code a E14-SFE0000521
035
(OCoLC)57715404
9
AJU6720
b SE
SFE0000521
040
FHM
c FHM
090
QE26.2 (ONLINE)
1 100
Lazareva, Olesya.
0 245
Detailed geochemical and mineralogical analyses of naturally occurring arsenic in the Hawthorn Group
h [electronic resource] /
by Olesya Lazareva.
260
[Tampa, Fla.] :
University of South Florida,
2004.
502
Thesis (M.S.)--University of South Florida, 2004.
504
Includes bibliographical references.
516
Text (Electronic thesis) in PDF format.
538
System requirements: World Wide Web browser and PDF reader.
Mode of access: World Wide Web.
500
Title from PDF of title page.
Document formatted into pages; contains 140 pages.
520
ABSTRACT: In order to understand the mineralogical association and distribution of arsenic (As) in the Hawthorn Group in central Florida, I examined in detail the chemical and mineralogical composition of 361 samples that were collected from 16 cores. Geochemical analyses were performed by hydride generation atomic fluorescence spectrometry (HG-AFS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The identification of discrete minerals was aided by scanning electron microscopy (SEM) and chemical compositions were obtained by electron-probe microanalyses (EMPA). Arsenic concentrations for all Hawthorn samples vary from 0.1 to 69.0 ppm with a mean of 5.6 ppm. Average As concentrations for the individual units of the Hawthorn Group vary significantly from 9.0 ppm in the Peace River Formation to 3.0 ppm in the Tampa Member of the Arcadia Formation.This detailed mineralogical and geochemical study demonstrates that: (1) Arsenic in the Hawthorn Group varies from the formation to formation and is primarily concentrated in trace minerals, such as pyrite; (2) Concentrations of arsenic in pyrite crystals can vary drastically from a minimum of 0 ppm to a maximum of 8260 ppm; (3) Pyrite occurs in framboidal and euhedral forms and is unevenly distributed throughout the Hawthorn Group; (4) Hydrous ferric oxides can contain up to 540 ppm of arsenic; (5) Phosphate and organic material, and clays contain lower arsenic concentrations that pyrite and hydrous ferric oxides; and (6) Arsenic, sulfur, and iron have lognormal distribution throughout the Hawthorn Group. This study is important because phosphorous, arsenic and sulfur are chemically closely related, and thus they co-occur posing a potential problem for the phosphate industry.Information about the concentration, distribution and mineralogical association of naturally occurring arsenic is essential to forecast its behavior during anthropogenically induced physico-chemical changes in the aquifer. Recently, aquifer storage and recovery (ASR) facilities in west-central Florida reported arsenic concentrations in excess of 100 micro g/L (100 ppb) in recovered water. The ASR storage zone in this area is in the Suwannee Limestone, which directly underlies the Hawthorn sediments. It is crucial to the future of ASR in this area to understand the source, distribution, and cycling of arsenic in the overlying Hawthorn Group and the Florida Platform.
590
Adviser: Pichler, Thomas.
653
phosphate.
mining.
pyrite.
aquifer.
trace metal.
Florida.
690
Dissertations, Academic
z USF
x Geology
Masters.
773
t USF Electronic Theses and Dissertations.
4 856
u http://digital.lib.usf.edu/?e14.521