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Spatial and temporal chemical variations in the Hillsborough River system

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Title:
Spatial and temporal chemical variations in the Hillsborough River system
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Book
Language:
English
Creator:
Pillsbury, Lori A
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla.
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Subjects

Subjects / Keywords:
seasonal cycles
phosphate
carbonate
pH
major ions
Dissertations, Academic -- Marine Science -- Masters -- USF   ( lcsh )
Genre:
government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
ABSTRACT: The Hillsborough River flows southwesterly through Pasco and Hillsborough counties in west central Florida. From its source at the Green Swamp to its mouth in Hillsborough Bay, the river is joined by many tributaries and man-made inputs. Spatial and temporal variations in the river's major ion and CO2 system chemistry were examined in a two-year study between 1999 and 2001. At thirteen sampling stations along approximately 54 miles of the river, water samples were collected in surroundings that ranged from pristine to urban. Samples were collected monthly for the first year and periodically thereafter. Concentrations of major ions were lowest in the river's headwaters, showed only minor spatial variations in mid-river, and sharply increased in tidally influenced waters below a dam on the lower river. A major tributary, Blackwater Creek, exerts a strong influence on the river's phosphate concentrations, and Crystal Springs, upstream of Blackwater Creek, exerts a strong influence on nitrate concentrations in the river. Downstream of Crystal springs, NO3- concentrations decreased steadily to levels that are more than an order of magnitude lower than levels in the upper river. Temporal ion concentration variations can be quite large. Low major ion concentrations were observed in the rainy season (June-September), while phosphate concentrations increased dramatically during extremely wet conditions. Seasonal variations were also observed in the river's CO2 system. Riverwater pH decreased during periods of high precipitation along with CaCO3 saturation state. CaCO3 supersaturation was observed during the exceptionally dry periods of the study, and undersaturation was observed during periods of high rainfall. Overall, the chemistry of the Hillsborough River is greatly influenced by temporal and spatial variations in the river's tributaries, groundwater sources, and anthropogenic inputs.
Thesis:
Thesis (M.S.)--University of South Florida, 2004.
Bibliography:
Includes bibliographical references.
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Mode of access: World Wide Web.
Statement of Responsibility:
by Lori A. Pillsbury.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 71 pages.

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aleph - 001461866
oclc - 54908673
notis - AJQ2278
usfldc doi - E14-SFE0000223
usfldc handle - e14.223
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ABSTRACT: The Hillsborough River flows southwesterly through Pasco and Hillsborough counties in west central Florida. From its source at the Green Swamp to its mouth in Hillsborough Bay, the river is joined by many tributaries and man-made inputs. Spatial and temporal variations in the river's major ion and CO2 system chemistry were examined in a two-year study between 1999 and 2001. At thirteen sampling stations along approximately 54 miles of the river, water samples were collected in surroundings that ranged from pristine to urban. Samples were collected monthly for the first year and periodically thereafter. Concentrations of major ions were lowest in the river's headwaters, showed only minor spatial variations in mid-river, and sharply increased in tidally influenced waters below a dam on the lower river. A major tributary, Blackwater Creek, exerts a strong influence on the river's phosphate concentrations, and Crystal Springs, upstream of Blackwater Creek, exerts a strong influence on nitrate concentrations in the river. Downstream of Crystal springs, NO3- concentrations decreased steadily to levels that are more than an order of magnitude lower than levels in the upper river. Temporal ion concentration variations can be quite large. Low major ion concentrations were observed in the rainy season (June-September), while phosphate concentrations increased dramatically during extremely wet conditions. Seasonal variations were also observed in the river's CO2 system. Riverwater pH decreased during periods of high precipitation along with CaCO3 saturation state. CaCO3 supersaturation was observed during the exceptionally dry periods of the study, and undersaturation was observed during periods of high rainfall. Overall, the chemistry of the Hillsborough River is greatly influenced by temporal and spatial variations in the river's tributaries, groundwater sources, and anthropogenic inputs.
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Spatial and Temporal Chemical Variat ions in the Hillsborough River System by Lori A. Pillsbury A thesis submitted in partial fulfillment of the requirement s for the degree of Master of Science College of Marine Science University of South Florida Major Professor: Robert Byrne, Ph.D. Benjamin Flower, Ph.D. Edward VanVleet, Ph.D. Date of Approval: March 2, 2004 Keywords: major ions, pH, carbonate, phosphate, seasonal cycles Copyright 2004, Lori A. Pillsbury

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i Table of Contents List of Tables ii List of Figures iii Abstract v Introduction 1 Sampling Strategies 13 Materials and Methods 15 Major ions and phosphate 15 Preparation of Sample Bottles 15 Sample Collection 15 Laboratory Analyses 16 Major ions 16 Phosphate 17 Spectrophotometric pH 18 CaCO3 Saturation State 19 Results/Discussion 21 Spatial Distributions 21 Temporal Variations 28 Riverine Input Mechanisms 33 Summary and Overview of Hillsborough River Chemistry 42 References 44 Appendices 47 Appendix I: Dionex DX -500 Ion Chromatograph specifications 48 Appendix II: Standard concentrations for cation and anion analyses 49 Appendix III: Reagent preparation for PO4 analysis 50 Appendix IV: Calculated ionic strengt h for each sampling station 51 Appendix V: Cation concentrations in the Hillsborough River (M) 52 Appendix VI: Anion concentrations in the Hillsborough River (M) 58 Appendix VII: PO4 concentrations in the Hillsborough River (M) 61 Appendix VIII: Calculated (Saturation State) values 64

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ii List of Tables Table 1 Hillsborough River Tr ibutaries (input/output) 9 Table 2 USGS Rainfall Data, Hillsborough River Drainage Basin 10 Table 3 Hillsborough River Syst em sampling locations 14 Table 4 Average concentrations of ma jor ions at sampling locations in this study 22 Table 5 Comparison of Hillsborough River water, spring water, and groundwater 25 Table 6 Comparison of major ion concentrations in the Hillsborough River (Stations 11-13) to seawater and Sulphur Spring 27 Table 7 Spectrophotometric pH meas urements by sampling station, T = 25 C 32 Table 8 Comparison of major ion concentrations in the Hillsborough River to mean concentrations in North American and World Rivers 39

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iii List of Figures Figure 1 Hillsborough River System 2 Figure 2 Hillsborough River and Tributaries 3 Figure 3 Florida Carbonate Platform 5 Figure 4 Historical streamflow totals (open symbols, ) versus totals streamflow (closed symbols, ) for the sampling period (Sept. 1999 Nov. 2001). 11 Figure 5 USGS Rainfall Data for Hillsborough River Drainage Basin (09/1999 – 11/2001) versus historical averages for September through November (1912 – 2001). 12 Figure 6 Average concentrations of major ions in the Hillsborough River by sampling station. 24 Figure 7 Ca2+ and Mg2+ average concentration, Stations 3-9, throughout the sampling period. 29 Figure 8 K+ and Na+ average concentration, Stations 3-9, throughout the sampling period. 30 Figure 9 Concentration of PO4 3in the Hillsborough River showing a correlation between rainfall totals and PO4 3concentration. 34 Figure 10 Relationship between spectr ophotometric pH and rainfall measurements for the time period May 2001 – Nov. 2001. 35 Figure 11 CaCO3 saturation state ( ) by sampling locati on 36 Figure 12 Relationship between Ca2+ and CA (carbonate alkalinity) in the Hillsborough River; r2 = 0.978, slope 1.93 0.05; represents outlying data points that were not considered when calculating the regression. 38

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iv List of Figures, continued Figure 13 Correlation between concentrations of Na+ vs. Clat (a) Stations 1 – 9 (r2=0.991) and (b) Station 10 (r2=0.993) and 11-13 (r2=0.972). 41

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v Spatial and Temporal Chemical Vari ations in the Hills borough River System Lori A. Pillsbury ABSTRACT The Hillsborough River flows southwesterly through Pasco and Hillsborough counties in west central Flor ida. From its source at the Green Swamp to its mouth in Hillsborough Bay, t he river is joined by many tributaries and man-made inputs. Spatial and temporal variations in the river’s major ion and CO2 system chemistry were examined in a two-year study between 1999 and 2001. At thirteen sampling st ations along approximately 54 miles of the river, water samples were collected in surroundings that ranged from pristine to urban. Samples were collected monthly for the first year and periodi cally thereafter. Concentrations of major ions were lowest in the river’s headwaters, showed only minor spatial variations in mid-river, and sharply increased in tidally influenced waters below a dam on the lower river. A major tributary, Blackwater Creek, exerts a strong influence on the river’ s phosphate concentrations, and Crystal Springs, upstream of Blackwater Creek, exerts a strong influence on nitrate concentrations in the river. Do wnstream of Crystal springs, NO3 concentrations decreased steadily to levels that are mo re than an order of magnitude lower than levels in the upper river. Temporal i on concentration variations can be quite large. Low major ion concentrations were observed in the rainy season (June –

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vi September), while phosphate concentra tions increased dramatically during extremely wet conditions. Seasonal variati ons were also observed in the river’s CO2 system. Riverwater pH decreased during periods of high precipitation along with CaCO3 saturation state. CaCO3 supersaturation was observed during the exceptionally dry periods of the study, and undersaturation was observed during periods of high rainfall. Overall, the c hemistry of the Hillsboroug h River is greatly influenced by temporal and spatial variat ions in the river’s tributaries, groundwater sources, and anthropogenic inputs.

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1 Introduction The Hillsborough River flows approximately 54 miles from its source in the Green Swamp to its mouth at Hillsborough Ba y (Figure 1). Used for over 10,000 years by Timucuan, Calusa, and Seminole I ndians, the river was originally called the Lockcha-popka-chiska, meaning “river where one crosses to eat acorns” (Florida Department of Natural Resource s, 1989). The river was renamed by the British presumably afte r the Earl of Hillsborough. Along the banks of the river, there are many hist orical and archaeological sites. These include Native American burial mounds, Fort Foster (built during the Seminole wars), and several historic buildings along the lower river. As the river flows toward Hillsborough Bay, water is added from several tributaries and springs, Figure 2. Cryst al Springs is the major source of freshwater for the river. Once a recreation area open to the public, Crystal Springs is now the major source of wate r for the Zephyrhills Sp ring Water bottling facility. South of Crystal Springs lies a unique tributary of the Hillsborough River, Blackwater Creek. Blackwater Creek drains a large agricultural and phosphate processing area and adds nutrien ts to the river. Following a southwesterly flow, the river moves through pine forests and swamps with palmetto undergrowth. T hese upper reaches of the river are

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2 Figure 1 – Hillsboroug h River System

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3 pristine. A variety of w ildlife flourishes here includin g several threatened or endangered species such as the gopher to rtoise, the bald eagle, the American alligator, and the Eastern indigo snake. The water is very clear and moves swiftly over a bottom substrate mostly co mposed of silt and mud with occasional limestone outcroppings. North of Hills borough River State Park, rapids are present at a few spot s along the river. Figure 2 – Hillsborough Riv er and Tributaries (compiled from USGS Quadrangle Maps and a Stat e of Florida Atlas) The State of Florida and Hillsborough Co unty operate several parks in this region, including Hillsborough River State Park, where visitors can experience

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4 the river and its wildlife through campi ng, canoeing, and hiking. The county parks provide similar activities and are open to the public year round. In this area, water is added to the river via two major tributaries, Flint Creek and Trout Creek. Near Trout Creek, a sinkhole c onnects the river to the underground Floridan Aquifer (Wolanksy and Thompson, 1987). After it passes beneath Fletcher Avenue (CR 582), the Hillsborough River moves through a residential area and passes into the City of Temple Terrace. Here the river takes on a new appearance. Natural banks are replaced in some areas by riprapped or concrete walls, and storm drain outfalls empty directly into the river. The surrounding area here is mostly residential with a few county and city parks providing public boat access. After flowing through the City of Temple Terrace the river becomes a reservoi r in Tampa just above a dam at 30th Street. This reservoir is a source of surface water for wate r treatment facilities that provide potable water for the City of Tampa. The dam restricts fr eshwater flow to the remainder of the river, especially durin g low flow periods. As it flows through the City of Tampa below the dam, the Hillsborough River is brackish. The water in this area is affected by tidal flows, stormwater and industrial run-off, and a major input, Sulphur Springs (The Flor ida Springs Task Force, 2000). Surrounded by skyscrapers, the Hillsborough river flows into Hillsborough Bay in downtown Tampa. River water chemistry is influenced by factors including geology, land use, and water use (Berner and Berner, 1987). From its source in the Green Swamp to its confluence with Hills borough Bay, the Hillsborough River flows over the

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5 Figure 3 – Florida Carbonate Plat form (Tihansky and Knochenmus, 2001) limestone (CaCO3) platform on which the entire State of Florida is situated (Figure 3) (Tihansky and Knochenmus 2001). The regional geology is comprised of a sequence of limestone and dolomite layers underlying sand and clay (Tihansky and Knochenmus, 2001). The uppermost substrate of the river is mostly decaying organic matter/muds and s and. Weathering/ dissolution of this substrate and underlying regional platform affects the chemical composition of the water. The river is fed by two major springs, Crystal Springs and Sulphur Springs. Crystal Springs is the largest fr eshwater source for the river. It is classified as a second magnitude spring (6.5 – 65 million gallons per day (MGD) flow) (Spechler, 1995) and, based on av erages from 1923 – 1982, historically

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6 contributed ~ 38 MGD of water to the river (Tihansky and Knochenmus, 2001). More recent measurements (1993 – 1994) i ndicate the flow has been reduced to ~ 24 MGD, little more than half the histor ical flow (Sepulveda, 2001). Prior to 1996, Crystal Springs and the surrounding la nd, though privately held, were open to the public as the Crystal Springs Re creation Preserve. Water was pumped out of the spring and trucked to the Zephyrhil ls drinking water bottling facility. In 1996 the owners of the land surrounding Cryst al Springs closed the recreational facility to the public. Through an under ground pipeline, pumping currently proceeds directly from the spring to the bo ttling facility, at more than 0.3 MGD. Recent changes to the water use permit allow pumping to incr ementally increase over the next five years to an average da ily withdrawal of ov er 0.75 MGD with a maximum of 1.1 MGD. Sulphur Springs enters the river in the City of Tampa below the Hillsborough River Dam. Also classified as a second magnitude spring (The Florida Springs Task Force, 2000), it c ontributed ~ 27 MGD to the Hillsborough River between 1959 and 1982 (Wolanksy and Thompson, 1987). Like Crystal Springs, more recent measurements (1993 – 1994) indicate a reduced flow (~ 16 MGD) (Sepulveda, 2001). During times of low precipitation/ low river flow, onethird of the Sulphur Spring’s flow is pumped into the Hillsborough River Reservoir (above the dam) to augment the city’s dr inking water supply (The Florida Springs Task Force, 2000). Beginning in the late 1800s, Sulphur Springs was a popular recreation area. The spring was purchas ed by the City of Tampa in 1957. A concrete pool was constructed, and the spring was operated as a public

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7 recreation area until 1986 when it was cl osed indefinitely due to bacterial contamination (The Florida Springs Task Fo rce, 2000). Plans for restoration of the spring are currently being considered. In addition to inputs from two major springs, water is also added to the Hillsborough River by numer ous natural and man-made tributaries. These tributaries, running through urban, agricultural, residential, and pristine lands (Figure 3 and Table 1), greatly affect the river’s chemistry. The Hillsborough River’s drainage basin includes areas north of Zephyrhills, east of Lakeland, and most of Hillsborough County (Figure 1). The Hillsborough River can be divided into lower, middle, and upper sections according to land use. The lowe r brackish section runs through a highly industrialized area within the City of Ta mpa downstream from the Hillsborough River Dam (which restricts freshwater flow into this portion of the river). The middle river, just above the dam and northward to the e dge of the City of Temple Terrace, is mostly residential. The upper river, from the edge of Temple Terrace north to its origin in the Green Swamp, is pristine and consists mostly of publicly held land (Florida Department of Natural Resources, 1989). The Hillsborough River is vitally im portant to the surrounding area. Though considered a small river, it is the major source of freshwater for the City of Tampa. The Hills borough River Reservoir holds 1.7 billion gallons of raw water. This water is supplied by the Hillsborough River, Sulphur Springs, and, during a recent drought (1999 – 2001), also from a sinkhole located near Morris Bridge Road. This sinkhole was connected to the reservoir via an above ground

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8 pipeline (Tampa Bay Water, 2002; S outhwest Florida Water Management District, 2002 ). Two facilities locat ed on the river supply approximately 65 MGD of potable processed reservoir water to approximately 450,000 Tampa residents (Tippen, 1999 & 2000). The depth of the river is insufficient for commercial shipping. Boat traffic is mostly recreational. Motorized boats are permitted on all parts of the river. However, some parts of the river ar e only accessible via kayak or canoe. The Southwest Florida Water Managem ent District (SWFWMD), the Hillsborough County Environmental Protection Commi ssion, the Florida Department of Environmental Protection, the Flor ida Fish and Wildlife Conservation Commission, and the United States Geologica l Survey (USGS) regularly monitor water quality and stream flow. These water quality data include pH, dissolved oxygen, turbidity, temperature, salinity coliforms, and biological oxygen demand (BOD). My investigation of the Hillsborough River was conducted from September 1999 until November 2001. During this period, the Hills borough River Basin experienced drought conditions. For an eighteen month period between September 1999 and November 2001, rainfall totals were below the 1915 2001 historical average (Table 2). May and October 2000 rainfall totals were the lowest on record. The low rainfall totals led to a decrease in river flow. USGS measurements of streamflow of the Hillsborough River for the period between Sept. 1999 and Nov. 2001 are shown in Figure 4.

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9 TABLE 1 – Hillsborough River Tributaries (input/output) a Tributary Name General Description Location of Intersection with Hillsborough River Port Lonesome Ditches & Fish Hatchery Drain Origin in swamps in E. Pasco/W. Polk counties, northwesterly flow Intersect at various locations, near boundary of Hillsborough and Withlacoochee River in Pasco County Zephyrhills Drain Origin NW of Zephyrhills, flows S/SE receiving stormwater runoff from Zephyrhills Intersects river 0.25 miles upstream of Crystal Springs Big Ditch Originates in swamps in NE Hillsborough County and Polk County, flows W through a phosphate processing area Intersects the river approximately 1.25 miles downstream of Crystal Springs Blackwater Creek This wate rshed extends into Polk County, Receiving water from major tributaries: East Canal flows north, receiving city and agricultural runoff; Itchepackesassa Creek originates in Polk County, flowing northwest it receives runoff from agricultural and residential areas as well as industrial discharge. Blackwater Creek, after being joined by its tributaries, flows westward through agricultural lands and intersects the river just upstream of Hillsborough River State Park Indian Creek b Originates approximately 2 miles west of Zephyrhills, flows S draining agricultural lands Intersects river approximately 0.5 miles downstream from the US 301 intersect Basset Branch & New River b Origin in swamps N of SR 54 in Pasco County, flows S through agricultural lands Both intersect the river within the boundaries of Hillsborough River State Park Two Hole Branch b South of Blackwater Creek extends west from SR 39, flows NW draining residential and agricultural lands, crossing US 301 Intersects river approximately 1.75 miles west of the US 301 intercept Hollomans Branch b Extends from SR 39 near Plant City to US 301, NW flow receiving runoff from residential and agricultural lands Intersects river approximately 1 mile downstream of US 301 Cypress Creek including Thirteen & Seventeen Mile Run Drains rural lands in Pasco and NW Hillsborough County Main channel empties into the river Trout Creek & Clay Gully West b Originates in Pasco County near Cabbage Swamp, flows S through residential developments Intersects river east of I-75 Tampa Bypass Canal Man-made structure with flow control system to alleviate flooding conditions for the cities of Temple Terrace and Tampa, originates near Trout Creek Park Diverts flood waters from river, main canal drains into Palm River, small ditches drain into residential or commercial land areas a Compiled from www.hillsboroughriver.org and Wolansky and Thompson, 1987. b Intermittent or non-perennial tributary

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10 TABLE 2 USGS Rainfall Data, Hillsbor ough River Drainage Basin (Sept. 1999Nov. 2001) (Southwest Florida Water Management District, 2002a) Sampling Months Rainfall Totals by Month (inches) Historical Rainfall Average (inches) 1999 2000 2001 (1915 – 2001) January 3.27 a 1.79 1.46 2.54 February 0.25 a 0.66 0.72 2.98 March 1.21 a 0.52 6.81 3.77 April 1.05 a 1.33 0.22 2.57 May 3.58 a 0.10 0.54 3.84 June 9.77 a 8.17 8.51 7.66 July 4.84 a 8.81 9.88 8.21 August 6.86 a 7.38 6.48 8.12 September 4.57 7.01 12.15 6.94 October 4.14 0.05 1.27 2.92 November 2.33 1.70 0.33 1.91 December 1.58 1.12 1.05 a 2.33 Annual Totals 43.44 38.63 49.43 53.86 a These data, included for completeness, are not sh own in Fig. 4, which represents rainfall only during the sampling period. Although yearly rainfall totals (1999 – 2001) were below the historical averages, monthly precipitation was c onsistent with the normal pattern of increased rainfall in the summer months (beginning in April through September) and reduced rainfall in the winter months (F igure 5). Substantial variations in river chemistry were observed in conjunction with seasonal changes. The objective of my thesis res earch, which principally involved measurements of t he Hillsborough River’s major ion composition, was a

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11 FIGURE 4 Historical streamflow totals (open symbols, ) versus streamflow totals (closed symbols, ) for sampling period (Sept. 1999 – Nov. 2001). A) USGS Monitoring station 02303000 located near Sampling station #3; B) USGS Monitoring Station 02303000 is located near Sampling Station #5; C) USGS Monitoring Station 02304500 is lo cated near Sampling Station #9. (United States Geological Survey, 2003) Month SepJanMaySepJanMaySepJan Streamflow, ft 3 /s 0 200 400 600 800 1000 1200 A Month SepJanMaySepJanMaySepJan Streamflow, ft 3 /s 0 200 400 600 800 1000 1200 Month SepJanMaySepJanMaySepJan Streamflow, ft 3 /s 0 200 400 600 800 1000 1200 B C

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12 FIGURE 5 USGS Rainfall Data for Hillsborough River Drainage Basin (09/1999 – 11/2001) versus historical averages for Sept. through Nov. (1912-2001). (Southwest Florida Water Management District, 2002) Month S e p J a n M a y S e p J a n M a y S e p J a n M a y Rainfall Total (inches) 0 2 4 6 8 10 12 1999 2001 Historical characterization of both spatial and tempor al variations in the river’s chemical composition. Observed vari ations in chemical compos ition provide insights into the river’s chemical source s, both natural and anthropogenic.

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13 Sampling Strategies Sampling locations were selected along approximately 54 miles of the river between the Green Swamp and Hills borough Bay (Tampa Bay). Sampling locations 1-10 (Figure 1) are upstream stations, and sampling locations 11-13 are downstream from the dam Individual sampling locations were chosen for accessibility as well as scientific interes t. Stations 11-13 are affected by tidal flow, causing the water at these stations to be bracki sh. Station 1 was chosen because it is the closest accessible locati on to Crystal Springs, which provides the majority of the river’s freshwater. Stations 2 and 6 are tributary stations, Blackwater Creek and Trout Creek. T hese locations provide insight into compositional differences between the tr ibutaries and the river. The remaining sample sites were distributed at conveni ent sampling points along the river. Table 3 provides GPS coordinates and a location description of all 13 sampling locations. Samples were collected monthly September 1999 through October 2000 and periodically thereafter. Shortly after sampling began, the Tampa Bay area experienced its worst drought in recorded hist ory. Therefore, t he majority of the samples were collected during unus ually dry, low flow conditions. At each sampling location, surface water samples were collected for analysis of major ions and phosphate. Spectrophotometric pH measurements

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14 were conducted for a limited number of sampling dates at Stations 1-10. General observations with respect to flow, weather conditions, and water clarity were also recorded. TABLE 3 Hillsboroug h River System sampling locations Hillsborough River System Sampling Locations Location # Description GPS coordinates 1 Bridge, CR 39 near Crystal Springs N 2811’35.6” W 08209’54.5” 2 Blackwater Creek, Bridge on CR 39 N 2808’22.0” W 08208’58.7” 3 Hillsborough River State Park, US Hwy 301 N 2808’55.2” W 08214’11.0” 4 John Sargent Park, US Hwy 301 N 2804’57.4” W 08217’08.4” 5 Wilderness Park, Morris Bridge Rd. N 2805’57.0” W 08218’43.1” 6 Trout Creek Park, Morris Bridge Rd. N 2805’16.5” W 08220’56.2” 7 USF Riverfront Park, Fletcher Ave. N 2804’10.6” W 08222’38.6” 8 Riverside Rotary Park, Fowler Ave. N 2803’16.4” W 08221’51.4” 9 Florida College, Bullard Pkwy. N 2801’59.1” W 08222’56.2” 10 Bridge, 40th St. N 2800’31.7” W 08224’51.9” 11 Lowry Park, Brevard St. N 2800’44.9” W 8227’53.2” 12 Corner of N. Lee & Rivershore Dr. off of W. Hillsborough Ave. N 2759’49.6” W 8228’11.9” 13 University of Tampa, W. Kennedy Blvd. N 2756’55.9” W 8227’51.8”

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15 Materials and Methods Major ions and phosphate Preparation of Sample Bottles Samples were collected in 250 mL low density polyethylene and Teflon bottles. All bottles were cleaned with Micro laboratory detergent and rinsed with deionized water. The bottles were then soaked for a minimum of 7 days in 4N hydrochloric acid. After removal from the acid, the bottles were triple rinsed with Milli-Q 18 M cm high purity water and set to dry in a laminar flow hood within a clean room. Prior to use, acid cleaned bottl es were stored in Fisher polyethylene bags. Polyethylene gloves were worn for all handling of bottles and at all times during the sampling process. Sample Collection Samples were collected from the bank of the river just below the surface via the following steps: 1) each bottle wa s removed from a Fisher polyethlyene bag and submerged with cap in place; 2) the bottle was uncapped beneath the surface, filled, and recapped; 3) the bo ttle was then removed from the water and emptied. These steps were repeat ed twice before the final sample was collected. After sample collection the capped bottle was dried with a Kimwipe

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16 and placed back in the polyethylene bag. Samples were transported to the laboratory within 6 hours of collection and refrigerated at < 10 C until analysis. Laboratory Analyses Major ions Na+, Mg2+, K+, Ca2+, Cl-, F-, NO3 -, and SO4 2were measured with a Dionex DX-500 ion chromatograph. As per EPA guidelines, anions were analyzed within 48 hours for NO3 and within 28 days for other anions (Pfaff, 1993). Chromatographic analyses were performed using instrumental conditions recommended by Dionex, Append ix I. Prior to each anal ysis, the chromatograph was equilibrated for at least 30 minutes to promote instrumental stability. A 1 mL sub-sample was injected directly into t he instrument’s sample intake port. One disposable, sterile syringe was used for each sample and was then discarded. Ion concentrations were determined based on a 3-point calibration line. All standards were prepared in Milli-Q 18 M cm high purity water. Standard concentrations and preparations are listed in Appendix II. The calibration line was determined prior to each sample run. Instrumental drift was monitored by periodically rerunning a standard solution. Due to instrumentation difficulties, anion data were only obtained for nine of the nineteen sampling dates. Therefore, conclusions re lating to general trends within the river are drawn only from the cation data. Carbonate alkalinity (CA) was calculated via cation/anion charge balan ce after determination of the other ions.

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17 Phosphate Samples were stored in the refrigerator (< 10 C) and analyzed for total phosphate ( PO4) within 24 hours of collection. PO4 was measured spectrophotometrically following the tec hnique described in Grasshoff et al. (1983). Reagents for the PO4 analysis were prepared as described in Appendix III. A 30 mL sub-sample was removed from each bottle via syringe and then discarded. A second 30 mL sample wa s removed with the same syringe and utilized for analysis. One mL of asco rbic acid reagent and one mL of mixed reagent was added to each 30 mL sample. Five minutes was allowed for color development. Samples were transferred to a 10 cm spectrophotometric cell. Absorbance was measured on an HP 8453 s pectrophotometer at a wavelength ( ) of 880 nanometers. To correct for the natural tannic color of the river water, each sample absorbance ( = 880 nm) was measured against a baseline consisting of natural river water. Each sample was measured three times. Total phosphate concentrations ( PO4) were determined based on a 3-point calibration line. Standards with concentrations of 0 M, 1M, and 5 M were prepared from a 10 mM PO4 3stock solution on the day of m easurement and analyzed following the procedure described above. During periods of unusually high phosphate concentrations, this procedure was modified slightly. When exceptionally high phosphomolybdate absorbances were observ ed, a 1 cm spectrophotometric cell was used in place of the 10 cm cell and the calibration curve included standards at 15 M and 25 M phosphate.

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18 Spectrophotometric pH As with the major ions and phosphate samples, pH samples were collected manually from the bank of the river. Samples were collected in 10 cm spectrophotometric cells (volume 26 cm3) as follows: 1) cells were submerged and filled without bubbles; 2) cells were capped with Teflon stoppers while submerged; 3) cells were removed from river and emptied. This process was repeated three times before a final sample was taken (Yao and Byrne, 2001). The cells were transported to the laborator y for immediate analysis. Samples for pH analyses were collected only from st ations 1-10. The ionic strength at stations 11-13 is too high for freshwat er pH measurement procedures (Yao and Byrne, 2001) More importantly, pH measurements at stations 11-13 were not of primary interest due to the stro ng influence of seawater on pH. Spectrophotometric cells were retu rned to the laboratory and equilibrated at 25 C for at least 30 minutes in a water-jacketed cell holder. Absorbances were measured with an HP 8453 diode a rray spectrophotometer: 1) each cell was removed from the thermostated hol der and its optical surfaces were cleaned, 2) baseline absorbances were measured at 433, 558, and 730 nm, 3) using a Gilmont microburet, 0.2 mL of phenol red indicator was added to each cell, 4) cells were manually mixed, 5) absorbances were again measured at 433, 558, and 730 nm. The pH was calculated using the following equations (Yao and Byrne, 2001): 3 2 1 1Re e e R log pK pH

PAGE 26

19 e1 = 0.00244, e2 = 2.734, e3 = 0.1075 AA AA R730 433 730 558 and 1/2 11 1/240 3 1 pKpKA 18.034 pK at 25 C and A = 0.5092 at 25 C = ionic strength calculated from majo r ion concentrations (see Appendix IV) CaCO3 Saturation State The CaCO3 saturation state ( ) was calculated from the major ion data following these steps. 1) Activity coefficients () were calculated using the following equation, (Stumm and Morgan, 1981): 1/2 2 1/2log0.509 0.3 (1)i Z where Zi is the charge of ion i. 2) The HCO3 dissociation constant (K2 ) at each ionic strength was calculated from the following equation: 3 2 3' 22 HCO COKK where K2 is the HCO3 dissociation constant at zero ionic strength,

PAGE 27

20 (K2 = 10-10.329) 3) The concentration of CO3 2was then calculated from the following equation: 1 2 3 2[] 2 H COCA K where 2 3 2 3[][] []HCO K HCO and 2 33[]2[]CAHCOCO carbonate alkalinity. 4) The CaCO3(s) solubility product for each sample (Ksp ) was calculated as: 22 3'1()spsp CaCOKK where K sp = 10-8.48 (Smith and Martell, 2001). 5) Finally, the saturation state () was calculated as follows: 22 3 '[][]spCaCO K Saturation state ( ) was only calculated for the sampling dates and locations where the pH was determined.

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21 Results/Discussion Spatial Distributions Originating in the Green Swamp and fl owing through a progressively more urbanized environment, the Hillsborough Ri ver water has a diverse set of geochemical influences. These influences on the evolving composition of the river as it flows from its source waters to Hillsborough Bay (Figure 6, Table 4) are described below. At Station 1, concentrations of th e major ions are comparable to or somewhat lower than concentrations observ ed on other parts of the river. Water here is derived mostly fr om the Green Swamp, but during times of high precipitation, sources ma y include water from the Withlacoochee River Basin (Wolanksy and Thompson, 1987). The average concentrations of Na+, K+, Cl-, SO4 2-, and PO4 (Table 4) are slightly elevated over groundwater levels seen at Crystal Springs (Table 5). These elev ated ion concentrations at Station 1 suggest possible inputs from sea-salt aer osols and/or agricultural run-off. Crystal Springs, located downstream fr om Station 1, provides a major input to the river directly from the aquifer. The majo r ion concentrations here are low with the exception of Ca2+ and CA which reflect the sp ring’s origins within the Karstian aquifer (Table 5). M easured concentrations of Na+ (243 M), K+ (9.9 M), F(7.5 M), SO4 2(96 M), and PO4 3(1.2 M) are lower

PAGE 29

22 TABLE 4 – Average concentrations of major ions at sampling locations in this study a (see Appendices V, VI, and VII for complete raw data) # Na+ K+ Mg2+ Ca2+ FClSO4 2NO3 CA b PO4 31 278 22 146 1449 11.6 264 150 10.2 2564 5.1 2 2120 344 288 1092 25 1684 696 30.2 2288 14 3 500 65 189 1375 19 457 174 70 2690 5.6 4d 509 64 194 1330 20 540 257 38 2475 5.8 5 504 64 194 1385 21 439 262 34 2612 6.5 6 478 58 217 1481 20 443 404 28 2755 5.1 7 451 56 213 1479 28 392 573 14 2145 4.6 8d 411 52 201 1371 26 410 506 12 2044 5.3 9 430 56 197 1360 21 406 477 7.7 2062 5.7 10 909 66 256 1461 21 1242 588 0 2019 4.8 11 61 x 103 1285 6900 3348 NAc 64 x 103 4391 NA NA 5.0 12 100 x 103 2107 11383 3909 NAc 125 6945 NA NA 5.4 13 255 x 103 5501 27435 6600 NAc 298 14106 NA NA 5.3 a All concentrations given in M and include only data from this study (9/99 – 11/01) b CA (carbonate alkalinity) is calcul ated from charge balance (CA = [HCO3 -] + 2[CO3 2-]), and at typical river pH [HCO3 -]>>[CO3 -]. c Due to required dilution of samples, this par ameter is below the instrument detection limit. d Due to unreliability of data, Sept. 1999 data are excluded for Station 8 and Jan. 2000 data are excluded for Station 4. than those at other locations on the river (Table 4). However, the NO3 concentration measured in Crystal Spri ngs is substantially higher than NO3 in other parts of the river. Station 1 is the only location with major ion concentrations closely comparable to Crystal Springs.

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23 Blackwater Creek enters the Hills borough River below Crystal Springs. Among the various Hillsborough River tri butaries, the water chemistry of Blackwater Creek (Station 2) is quite uni que. The mean concentrations of most major ions (except Ca2+ and CA) are substantially hi gher than the Hillsborough River average (Figure 6, Table 4). The average Na+ concentration (2120 M) is almost four times the mean for the mid -river (stations 3-9) (469 M), while K+, 344 M, is almost six times the mean mid-river value. Phosphate averages 14 M in Blackwater Creek compared to 5.5 M in the mid-river. Enrichment of ions in this tributary is a result of inputs that are unique to the area surrounding Blackwater Creek. Blackwater Creek is itself fed by three tributaries: Tiger Cree k, East Canal, and Itchepackesassa Creek (Florida Department of Environmental Protection, 2002). East Canal receives stormwater runoff from Plant City. Itchepackesassa Creek drains an area agricultural rangeland and receives industrial disc harge (Morgan and Dens on, 1995). From Figure 6 and Table 4, it is seen that s ubstantial dilution at the confluence of Blackwater Creek and the Hillsbor ough River decreases downstream concentrations of Na+, K+, Mg2+, Cl-, SO4 2-, and PO4 to much lower levels. Major ions concentrations in t he river immediately downstream of Blackwater Creek are essentia lly stable. Ion concentrations at stations 3,4, and 5 show little variation (Table 4, Figur e 6). The exceptio n to this is NO3 -, which originates in Crystal Springs. As water moves downstream, NO3 decreases steadily. Station 6 is located on another tr ibutary of the river, Trout Creek. At

PAGE 31

24 this location, water samples are enriched in Mg2+, Ca2+, and SO4 2-, while phosphate, K+, Na+, and Clare similar to concentrations upstream. Fshows an increase between Stations 6 and 7 and SO4 2shows a large increase FIGURE 6 Average concentrations of major ions in the Hillsborough River by sampling station. Station # 01234567891011 [PO 4 ] / M 4 6 8 10 12 14 16 ([F ], [NO 3 ]) / M 0 20 40 60 80 Station # 01234567891011 ([Na+] [Cl-] [SO4 2-]) / M 0 500 1000 1500 2000 2500 3000 ([Mg 2+ ] [K + ]) / M 0 100 200 300 400 500 F PO 4 Mg K Cl Na SO 4 Ca CA NO3

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25 TABLE 5 Comparison of Hillsborough Rive r water, spring water, and ground watera Location Na+ K+ Mg2+ Ca2+ FClSO4 2NO3 HCO3 Reference Crystal Springs 243 9.9 172 1533 7.5 308 96 150 3003 This study Crystal Springs 233 NA 172 1569 NA 274 94 60.6 2328 (Champion and Starks, 2001) HR – Station 1 278 22 146 1449 11.6 264 150 10.2 2564 b This study (mean 9/99 – 11/01 Florida Groundwater (Polk City)c 139 12.8 230 848 5.3 127 25 NA 2033 Back & Hanshaw, 1970 HR – Stations 3-9 469 59 201 1396 22 444 375 29.5 2396 b This study (mean 9/99 – 11/01) Florida Groundwater (Plant City)c 522 21 453 1646 21 339 -d NA 4000 Back & Hanshaw, 1970 Sulphur Springs 13913 248 1506 3516 NA 163382081 14.4 2443 (Champion and Starks, 2001) a All concentrations expressed in M; w hen necessary data were converted from or iginal (wt/wt) concentrations (e.g. ppm) b CA (carbonate alkalinity) concentrations are bas ed on charge balance and as such are actually [HCO3 -] + 2[CO3 2-]. At typical river pH, [HCO3 -]>>[CO3 2-]. c Groundwater samples taken from different depths, but considered part of the same hydrologic unit by the author; The Polk City s ample is considered to be drawn from water that feeds many of the springs in the area. d Value actually listed as zero.

PAGE 33

26 between Stations 5 and 7. A possible ex planation for the variations seen at Stations 6 and 7 is groundwater seepage. The USGS deter mined that the specific conductance of groundw ater here is greater than t hat of the local surface water. A sinkhole near Trout Creek ma y allow groundwater to seep into the surface water, especially during low fl ow conditions (Wolanksy and Thompson, 1987). Further investigation is r equired to unambiguously determine the mechanism for the significantly increased levels of Fmeasured at Station 7. At stations 8 and 9, major ion concent rations, with the exception of SO4 2-, are near the levels measured in Stations 3-5. Fconcentrations between Stations 8 and 9 decrease to levels appr oximately equal to those measured at Station 5. PO4 is near the average concentr ation encountered on the river. Concentrations of Na+, Ca2+, Mg2+, Cl-, F-, K+, and SO4 2at Station 10 are higher than those observed at Stations 8 and 9, and PO4 decreases slightly. Concentration changes are greatest for Na+ and Cl-: 430 M and 406 M at Station 9 compared to 909 M and 1242 M at Station 10. Stat ion 10 is located near the reservoir for the City of Tampa’s drinking water tr eatment facility (Fig. 1). During times of low flow or low precipit ation, this reservoir is augmented with water pumped from Sulphur Springs (Flori da Springs Task Force, 2000). During the drought between Sept. 1999 and Nov. 2001, augmentation of the surface water supply and the flow of the Hillsborough River became a necessity. Water was pumped into the reservoir from a sinkhole located on Morris Bridge Rd., the Tampa Bypass Canal, and also from Sul phur Springs (Tampa Bay Water, 2002; Southwest Florida Water Management Dist rict, 2002). Ion concentrations are

PAGE 34

27 enriched in Sulphur Springs and in other groundwater sources in this area (Table 5), and likely account for the increased ion concentrations at Station 10. Dissolved PO4 is low in groundwater. Consequently, increased groundwater pumping into the river ma y account for the reduced PO4 concentrations at Station 10. The Hillsborough River water below the Hillsborough River Dam is composed of inputs from Sulphur Springs flow over the dam, and tidal mixing from Hillsborough Bay. The concentrations of most ions at Stations 11-13 (Table 4) are several orders of m agnitude higher than those seen at Stations 1 10. Flow over the dam is variable and can be non-existent at times of very low precipitation. Table 6 compares the i on concentrations in the river below the dam with the waters of Sul phur Springs and seawater. TABLE 6 Comparison of major ion c oncentrations in the Hillsborough River (Stations 11-13) to seawat er and Sulphur Springs. a a All concentrations expressed in M. b S=35, density = 1.0248 kg/L used to convert original data from M/kg to M for comparison c Data not available. River Location Na+ K+ Mg2+ Ca2+ FClSO4 2Reference HR – Stations 11-13 139 x 103 2960 15200 4620 NAc 169 x 103 8772 This study (mean 9/99 – 11/01) Seawater b 481 x 103 10500 54100 10700 70 562 x 103 28900 (Byrne, 2002) Sulphur Springs 13.9 x 103 248 1506 3516 NAc 16.3 x 103 2081 (Champion and Starks, 2001)

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28 Temporal Variations Ions concentrations in the river exhi bit substantial temporal changes. Due to difficulties with anion concentra tion measurements fo r a portion of the sampling period, the following discussion principally explores trends for the cation data. Ca2+ and Mg2+ show a similar temporal pattern (Figure 7). This similarity may indicate a simila r source for these cations. Na+ and K+ also show a similar temporal pattern in the river (F igure 8). Since this study occurred during a drought period, changes in ion concent rations before and after Tropical Storm Gabrielle (Sept. 2001) were especially dramatic. Concentrations of all major cations, except K+ dropped by approximately 50 percent. Figure 9 depicts the concentration of PO4 in the Hillsborough River throughout the sampling period. As a tributary with greatly enhanced concentrations, Blackwater Creek (Station 2) is shown separately. PO4 levels measured at Stations 3-10 approached t hose found in Blackwater Creek only on September 19, 2001. Stat ion 1 and Station 10 are also show separately. Ion concentrations at Station 1 are genera lly distinct from trends in ion concentrations observed in the remainder of the river. Due to inputs previously discussed, ion concentration trends at Stat ion 10 are distinct from those in the mid-river. In concert with seasonal changes in precipitation and river flow, phosphate concentrations generally rise in June and peak in September. While phosphate

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29 Figure 7 – Ca2+ and Mg2+ average concentrations (M), Stations 3-9, throughout the sampling period. Error bars re present the total concentration range (minimum and maximum) for Stati ons 3-9 for each sampling date. Mg2+0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 Jan-01 Mar-01 May-01 Jul-01 Sep.13-01 Oct-01 Ca2+0.00 500.00 1000.00 1500.00 2000.00 2500.00Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 Jan-01 Mar-01 May-01 Jul-01 Sep.13-01 Oct-01

PAGE 37

30 Figure 8 – Na+ and K+ average concentrations (M), Stations 3-9, throughout the sampling period. Error bar s represent the total conc entration range (minimum and maximum) for Stations 3-9 for each sampling date. Na+ 0.00 200.00 400.00 600.00 800.00 1000.00 1200.00Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 Jan-01 Mar-01 May-01 Jul-01 Sep.13-01 Oct-01 K+0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 Jan-01 Mar-01 May-01 Jul-01 Sep.13-01 Oct-01

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31 concentrations in the river are str ongly dependent on precipitation and flow conditions, Blackwater Creek does not show this same pattern. Agricultural and industrial inputs to this tr ibutary may override seasonal effects. No definitive trends or patterns are seen in Blackwater Creek, as noted, and PO4 concentrations here (Station 2) are consis tently higher than t he remainder of the river. Only during maximum flow condi tions do phosphate concentrations in the river approach those seen in Blackwater Creek. Phosphate concentrations are generally low at Station 1 and a seasonal peak was seen in 2001 but not during 2000. The low phosphate concentrations at Station 1 may reflect the swampy, undeveloped surrounding area. Agricultural and industrial inputs here are generally low. The exc eptional phosphate concentrations in September 2001 may be attributable to the effects of Tropical Storm Gabrielle which brought 25 inches of rain to the basin in the period Sept. 13-15, 2001. At high water stages, the headwaters of the river may have been connected to the Withlacooc hee River basin or other surrounding surface waters (Wolanksy and Thompson, 1987). Large temporal changes are also seen in river pH. During the measurement period, spectrophotometric ally determined pH in the river ranged from a low of 6.52 to a high of 8.805, Tabl e 7. Rainfall in Florida has a slightly acidic pH, while the average pH of Florida groundwater is between 7 and 8 (Champion and Starks, 2001). Water that has been in contact with the limestone substrate for an extended period of time will tend toward saturation with respect to CaCO3 and high river pH. Conversely, water with < 1 and low pH indicates

PAGE 39

32 a low contact time with the substrate and points to recent precipitation as a causative factor. Figure 10 shows an in verse relationship between the average spectrophotometric pH and rainfall bet ween May and November (2001). Figure 11 shows the values calculated for the samp ling stations in the same time period. The river is supersaturated fo r the months of May and June 2001 due to low precipitation. Increases in prec ipitation during the months of August, September, and November create CaCO3 undersaturation. A complete table with the calculated values can be found in Appendix VIII. TABLE 7 Spectrophotometric pH m easurements by sampling station, T = 25 C. # May 2001 June 2001 Aug 2001 Sept 2001a Nov 2001 1 7.394 7.482 6.975 6.686 7.375 2 7.388 7.773 7.256 6.638 7.308 3 7.892 7.76 7.290 6.852 7.573 4 8.066 7.931 6.782 6.570 7.208 5 8.085 7.891 6.778 6.525 7.304 6 8.010 7.755 6.751 NAb 7.263 7 7.908 7.719 6.646 6.521 7.289 8 7.858 7.727 6.690 6.541 NAb 9 7.905 7.614 6.698 6.584 7.249 10 7.986 8.390 7.000 6.769 7.793 Average 7.849 7.804 6.886 6.630 7.373 a September 2001 data applies to the sampling date Sept. 19, 2001 b Sampling sites inaccessible on these dates due to heavy rainfall.

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33 Riverine Input Mechanisms Cationic and anionic concentrations in the river have the following order: Ca2+>Na+>Mg2+>K+ and HCO3 ->Cl->SO4 2->F-. While this follows the general order of other North American rivers (Table 8), the Hillsborough River is distinctive in a number of respects. The average mid-river HCO3 concentration, 2396 M, is more than two times the North American average. The average Ca2+ concentration (Stations 3 to 9), 1396 M is more than two times the North American average and seven ti mes the world average. Na+ and Clare also somewhat enriched in the Hillsborough Ri ver compared to North American and World Rivers. The Na+ average (Stations 3-9) (469 M) is close to the Actual North American average reported by Ber ner and Berner (1987) (365 M), but greater than the Mean World Rivers value of 161 M given by Markich and Brown (1998). The average (Stations 3-9) Clconcentration was also enriched, 444 M (HR) compared to 260 M cited by Berner and Be rner (1987) and 110 M (Mean World Average) reported by Markich and Brown (1998). The average SO4 2concentration in the rive r is double the North American average reported by Berner and Berner (1987) and greater than seven times the world average (Markich and Brown, 1998). K+ concentrations in the Hillsborough River are nearly double the Mean World Ri vers reported by Markich and Brown (1998) and higher than the No rth American average of 38 M reported by Berner and Berner (1987). Phosphate concentra tions in the Hillsborough River are several times greater than those seen in North American

PAGE 41

34 FIGURE 9 Concentration of PO4 3in the Hillsborough River showing correlation between rainfall totals and PO4 3concentration. (A) Stations 3-9 (B) Station 1, Blackwater Creek (S tation 2), and Station 10. 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00Sept. 99 Jan. 00 May 00 Sept. 00 Jan. 01 May 01 Sept. 01Date[ PO4], mol 3 4 5 6 7 8 9 summer rain peaks Stations 3-9 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00Sept. 99 Jan. 00 May 00 Sept. 00 Jan. 01 May 01 Sept. 01Date[ PO4], mol 1 2 10

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35 FIGURE 10 – Relationship between spectrophotometric pH and rainfall measurements for the time period May 2001 – Nov. 2001 (this study, (Southwest Florida Water Management District, 2002)). 2001 AprMayJunJulAugSepOctNovDec average pH 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 Average Rainfall (inches) 0 2 4 6 8 10 12 14 pH Rainfall pH Rainfall

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36 Figure 11 CaCO3 saturation state ( ) by sampling location. Sampling Location 01234567891011 log -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 May June Nov Aug Sept and World river averages. Differences between the Hillsborough River and North American and World Rivers are attributable to a va riety of influences. Some of the complex processes that deliver ions to the Hillsborough River are unique to the Hillsborough River basin, while other s are common to most rivers. Ca2+ and the CA in the Hillsborough Rive r are primarily influenced by the CaCO3 composition of the Florida platform (Figure 2). As illustrated by the following process:

PAGE 44

37 2 32232 CaCOCOHOCaHCO the expected HCO3 / Ca2+ ratio for dissolution of pure limestone is 2 (Drever, 1997). Samples taken from Crystal Springs show a CA / Ca2+ molar concentration ratio equal to approximatel y 2.1 (Table 5). Groundwater samples from Polk City and Plant City show simila r ratios, ~ 2.4. Due to the important contributions of CaCO3(s) to the composition of the Hillsborough River, the average CA / Ca2+ ratio is also close to 2 (Figure 12). This relationship suggests that most of the alkalinity in the rive r can be attributed to the dissolution of CaCO3. (For pure limestone, CA / Ca2+ ~ 2, e.g. the dissolution of CaCO3 adds 2 mols of alkalinity per mol of Ca2+ (see above equation)). Na+ and Clconcentrations in the river ar e substantially higher than seen in groundwater samples. Na+ and Claveraged 463 M and 444 M in the river, but in Florida groundwater, Na+ and Clconcentrations average less than half that of the river. One spring that shows an exception to this is Sulphur Springs. The Na+ (5000 M) and Cl(5726 M) concentrations her e are greatly enriched. Na+ and Clin the river are strongly correlated (Figure 13). The calculated Cl/ Na+ molar ratio for Stations 1-9 is 0. 68 0.007. This ratio is somewhat smaller than that observed at Crystal Springs (0.78). At Station 10 the Cl/ Na+ ratio is1.27 0.04, and at Stations 11-13, the ratio is 1.23 0.06 (Figure 13). Berner and Berner (1987) calculated that in world rivers 8% of the Na+ and 13% of the Clis a product of atmospheric sea sa lt. They attributed the majority of the Na+ and Cl-, 42% and 57%, to the dissolution of evaporates (halites). Another Na+ and Clenrichment mechanism is run-off including

PAGE 45

38 FIGURE 12 Relationship between Ca2+ and CA (carbonate alkalinity) in the Hillsborough River; r2=0.978, slope 1.93 0.05; represents outlying data points that were not considered when calc ulating the regression. These points are labeled with the station number where each sample was collected. They are from Aug. 2000 (#4, 5) and June 2000 (#2). [Ca 2+ ], M 200400600800100012001400160018002000 [CA] M 500 1000 1500 2000 2500 3000 3500 4000 #5 #4 #2 r 2 = 0.978 slope 1.93 0.05

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39 TABLE 8 Comparison of major ion concentrations in the Hillsborough River to Mean conc entrations in North America and World Rivers a River Location Na+ K+ Mg2+ Ca2+ FClSO4 2HCO3 PO4 3Reference HR – Stations 3-9 b 469 59 201 1396 22 444 375 2396 c 5.5 This study (mean 9/99 – 11/01) Mean World Rivers 161 26 99 200 NAd 110 50 NAd 0.1 Markich & Brown, 1998 N. America River Average 365 38 202 529 NAd 260 187 1185 NAd Berner & Berner, 1987 Average World Rivers 230 38 128 332 NAd NAd NAd NAd NAd Chester, 1990 a All concentrations expressed in M; when necessary data were converted from orig inal (wt/wt) concentrations (e.g. ppm). b Water at Station 1 consists of swamp water from a pristine area and is not representative of the mid river average and Station 2, Blackwater Creek, also has unique water chemistry. Station 10 is greatly in fluenced by input from Sulphur Springs as well as supplemental water from the Tampa Bypass Canal. These stations are cons idered separately and t herefore excluded here. c CA (carbonate alkalinity) concentrations are based on charge balance and as such are actually [HCO3 -] + 2[CO3 2-]. However, at typical river pH CA [HCO3 -] d Data not reported in original source

PAGE 47

40 domestic effluent (Berner and Berner, 1987). Rainwater enriched in sea-salt aerosols is one import ant source of Na+ and Clto Florida rivers (Madsen et al., 1992). The Hillsborough River receives inpu ts from stormwater outfalls and may also receive septic system leachate both directly and through historically contaminated groundwater inputs (Flo rida Springs Task Force, 2000). Saline groundwaters are an important source of Na+ and Cl-, and this source is may be especially important in the area downstream of the Sulphur Springs outfall. In the coastal transition zone, seawater intr usion plays a role in the ionic make-up of the groundwater. The molar ratio Cl/ Na+ in Sulphur Springs water is ~ 1.17, closely matching that of seawater (~1.15) The calculated ratios at Station 10 and 11-13 also closely match that of Sulphur Springs and seawater. Riverine SO4 2concentrations can be influenced by a variety of sources, some which are unique to the Hillsborough River drainage basin. Dissolution of gypsum (CaSO4), a by-product of the large phosphate mining and processing industry in Florida may be an espec ially significant source of SO4 2-. Other anthropogenic influences in the area incl ude agricultural run-off and industrial emissions. SO4 2enrichment is also a natural re sult of chemic al weathering, biological processes, and sea-salt deposition. Riverine K+ concentrations are affected by agr icultural run-off. Agricultural interests, extensive in Florida, utilize fertilizers rich in K+. Another source of K+ is the substantial amount of leaf litter/decaying organic matter in the river. K+ is more readily released from plant matter than most other ions (Berner and Berner,

PAGE 48

41 1987) The release of K+ from organic rich muds should be especially important in times of high precipitation. FIGURE 13 Correlation between concentrations of Na+ vs. Clat (a) Stations 19 (r2=0.991) and (b) Station 10 (r2 = 0.993) and 11-13 (r2 = 0.972). [Na+], M (Stations 11-13, Seawater) 01e+52e+53e+54e+5[Cl-], M (Stations 11-13, seawater) 0 1e+5 2e+5 3e+5 4e+5 5e+5 [Na+], M (Station 10) 0200400600800100012001400160018002000[Cl-], M (Station 10) 0 500 1000 1500 2000 2500 [Na + ], M 0100020003000400050006000 [Cl-], M 0 1000 2000 3000 4000 5000 a1 9 slope 0.68 0.007b10 slope 1.27 0.04 11 13 slope 1.23 0.06

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42 Summary and Overview of Hillsborough River Chemistry This study identified a variety of un ique inputs to the H illsborough River. Limestone dissolution is the major contro lling factor for calcium and carbonate concentrations in the river. The river’s major freshwater source, Crystal Springs, is the dominant source of nitrate (NO3 -) to the river. Due presumably to microbial respiration, NO3 steadily decreases downstream of this source. The mid-river stretch of the Hillsborough River (Stations 3 to 9) exhibited a fairly constant major ion composition. Blackwater Creek is a dominant source of PO4 to the river. Saline groundwater from Sulphur Springs and possible sinkhole linkages contribute major ions near the Hillsbor ough River dam (Station 10). Downstream of the Hillsborough River Dam (Stations 1013), the water chemistry more closely resembles that of seawater than the mid -river water. Flow over the dam is extremely low at times of low precipitation. This portion of the river is also tidally influenced. The ionic composition of the river va ries seasonally. Major ions were lowest at times of highest precipitation. This, however, was not the case for PO4 which exhibited high concentrations wi th increased precipitation. Seasonal variations were also seen in pH and CO2 system chemistry. The river’s pH decreased dramatically duri ng periods of high precipitation. Changes in pH

PAGE 50

43 induced by precipitation created lar ge variations in the river’s CaCO3 saturation state. During low precipitat ion, the river is supersaturated with respect to CaCO3. Periods of high precipit ation produce strong CaCO3 undersaturation. In conclusion, the chemistry of the Hillsborough River is influenced by complex interactions of many natur al and anthropogenic inputs. Temporal variations in the river’s chemistry is i dentified as a particula rly important area for future work. Chemical measurement s of particular importance include phosphate, nitrate (and other nitrogeneous species), solution pH, and associated CO2 system parameters.

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44 References Back, W. and Hanshaw, B. B. (1970) Comparison of c hemical hydrology of the carbonate peninsulas of Florida and Yucatan. Journal of Hydrology, 10, 330-368. Berner, E. K. and Be rner, R. A. (1987) The Global Water Cycle: Geochemistry and the Environment Prentice-Hall, Inc. Byrne, R. H. (2002) In Chemical Speciation in the Environment (Ure, A. M. and Davidson, C. M., Eds.) Blackwell Sc ience Ltd., Glasgow, pp. 322-357. Champion, K. M. and Starks, R. (2001) Southwest Florida Water Management District The Hydrology and Water Quality of Springs in West-Central Florida. Chester, R. (1990) Marine Geochemistry Unwin Hyman, London. Drever, J. I. (1997) The Geochemistry of Natural Waters: Surface and Groundwater Environments Prentice Hall Inc. Florida Dept. of Environmental Protection (2002) Hillsborough River Subwatershed Descriptions; http://www.hillsboroughriver.o rg/subwatershed_descriptions.htm. Florida Department of Natural Resources (1989) Florida Rivers Assessment. The Florida Springs Task Force (2000) Florida's Springs: Strategies for protection and restoration. Tallahassee Grasshoff, K., Ehrhardt, M. and KremLing, K. (Eds.) (1983) Methods of Seawater Analysis Huettel, S. (2000) Lower Hillsborough's fa te at center of legal debate. In St. Petersburg Times St. Petersburg. Madsen, B. C., Kheoh, T., Hinkle, C. R. and Dreschel, T. ( 1992) Precipitation chemistry in east central Florida from 1978 to 1987. Water, Air, & Soil Pollution, 65, 7-21.

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45 Markich, S. J. and Brown, P. L. (1 998) Relative importance of natural and anthropogenic influences on the fresh surface water chemistry of the Hawkesbury-Nepean River, south-eastern Australia. The Science of the Total Environment, 217, 201-230. Morgan, P. and Denson, D. (1995) Fl orida Department of Environmental Protection The Biological View: Hillsborough River System, Summer 1995. Pfaff, J. D. United States Envi ronmental Protection Agency (1993) Method 300.0 Determination of Inorganic An ions by Ion Chromatography. Method 300.0. Sepulveda, N. (2001) Comparison s among groundwater flow models and analysis of discrepancies in simula ted transmissivities of the upper Floridan Aquifer in groundwater flow model overlap areas. In U.S. Geological Survey Karst Interest Group (Kuniansky, E. L, Ed.) U.S. Geological Survey, St. Petersburg, FL, pp. 58-67. Smith, R. M. and Mart ell, A. E. (2001) NIST Critically Select ed Stability Constants of Metal Complexes Database. NIST, Gaithersburg. Southwest Florida Water Management Distri ct (2002a) Rainfall Data Distribution Center; http://www.swfwmd.state.f l.us/data/rain/rainfall.htm. Southwest Florida Water Management District (2002b) SWFWMD News; http://www.swfwmd.sta te.fl.us/news/2000. Spechler, R. M. United States Geological Survey (1995) Springs of Florida. FS151-95. Stumm, W. and Morgan, J. (1981) Aquatic Chemistry John Wiley & Sons New York Tampa Bay Water (2002) News Releas es; http://www.tampabaywater.org. Tihansky, A. B. and Knochenmus, L. A. (2 001) Karst features and hydrogeology in west-central Florida A field perspective. In U.S. Geological Survey Karst Interest Group Proceedings (Kuniansky, E. L., Ed.) U.S. Geological Survey, St. Petersburg, FL, pp. 198-211. Tippen, D. L. (1999, 2000) Tampa Water Department; Water Quality Report. Tampa. United States Geological Survey, USGS Realtime Water Data (2003).

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46 Wolanksy, R. M. and Thompson, T. H. U.S. Geological Survey (1987) Relation between groundwater and surface water in the Hillsborough River Basin, west-central Florida. 87-4010; Tallahassee Yao, W. and Byrne, R. H. (2001) Spectrophotometric de termination of freshwater pH using bromocresol purple and phenol red. Environmental Science & Technology, 35, 1197-1201.

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47 Appendices

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48 Appendix I Dionex DX-500 Ion Chromatograph specifications Cation Analysis Column Eluent Flow rate IonPac CS12A 20 mM methylsulfonic acid (MSA) 1.0 mL/min Anion Analysis Column Eluent Flow rate IonPac AS14 3.5 mM Na2CO3/ 1.0 mM NaHCO3 1.2 mL/min

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49 Appendix II Standard concentrati ons for cation and anion analyses Standard 1 Standard 2 Standard 3 Cations a M ppm M ppm M ppm Na+ 217 5 870 20 2175 50 K+ 26 1 102 4 256 10 Mg2+ 41 1 165 4 411 10 Ca2+ 125 5 499 20 1248 50 Standard 1 Standard 2 Standard 3 Anions b M ppm M ppm M ppm F10.5 0.2 42.1 0.8 105 2 Cl141 5 564 20 1410 50 NO3 16.1 1 64.5 4 161 10 SO4 252 5 208 20 520 50 a Cation standards were prepared from VHG Labs (Manchester, NH) Water Pollution Standard 5 containing: K+, Mg2+ at 100 g/mL (ppm); Ca2+, Na+ at 500 g/mL (ppm). b Anion standards were prepared from a VHG Labs (Manchester, NH) IC Custom Standard 1 containing: Cl-, SO4 2at 50.0 g/mL (ppm); NO3 at 10 g/mL (ppm); Fat 2.0 g/mL (ppm).

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50 Appendix III Reagent Preparation for PO4 analysis 1) ascorbic acid reagent – 5 g of ascorbic acid (C6H8O6) was dissolved in 25 mL Milli-Q water, 25 mL 4.5 M H2SO4 2) mixed reagent – Part 1 – 12.5 g ammonium heptamol ybdate tetrahydrate was dissolved in 125 mL Milli-Q water, Part 2 -0.5 g potassium antimony tartrate was dissolved in 20 mL Milli-Q water; Part 1 was added to 350 mL H2SO4 and stirred continuously, Part 2 added and mixed well. Reagent 1 was prepared mont hly, while reagent 2 remained stable for several months.

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51 Appendix IV – Calculated Ionic St rength for each sampling station a Station # 06/20/2000 7/24/2000 8/ 22/2000 5/02/2001 6/25/2001 8/27/200 1 09/13/2001 09/19/2001 11/19/2001 1 4.83 x 10-3 5.44 x 10-3 5.75 x 10-3 6.22 x 10-3 5.69 x 10-3 3.69 x 10-3 2.54 x 10-3 2.17 x 10-3 6.19 x 10-3 2 13.4 x 10-3 6.47 x 10-3 5.94 x 10-3 4.34 x 10-3 13.34 x 10-3 7.71 x 10-3 5.27 x 10-3 2.32 x 10-3 8.64 x 10-3 3 4.73 x 10-3 6.10 x 10-3 6.02 x 10-3 6.24 x 10-3 6.40 x 10-3 5.44 x 10-3 3.81 x 10-3 2.08 x 10-3 6.11 x 10-3 4 5.00 x 10-3 6.35 x 10-3 7.56 x 10-3 6.38 x 10-3 6.48 x 10-3 4.81 x 10-3 3.54 x 10-3 2.29 x 10-3 5.15 x 10-3 5 5.13 x 10-3 5.87 x 10-3 8.47 x 10-3 6.39 x 10-3 6.47 x 10-3 4.68 x 10-3 4.13 x 10-3 1.97 x 10-3 6.08 x 10-3 6 5.18 x 10-3 6.93 x 10-3 6.72 x 10-3 7.66 x 10-3 9.06 x 10-3 4.56 x 10-3 3.69 x 10-3 NA 5.77 x 10-3 7 5.01 x 10-3 6.94 x 10-3 9.49 x 10-3 8.54 x 10-3 8.57 x 10-3 4.83 x 10-3 NA 2.19 x 10-3 2.32 x 10-3 8 5.15 x 10-3 6.49 x 10-3 9.32 x 10-3 8.17 x 10-3 7.97 x 10-3 4.68 x 10-3 4.04 x 10-3 2.01 x 10-3 2.16 x 10-3 9 5.13 x 10-3 6.50 x 10-3 8.37 x 10-3 8.11 x 10-3 7.54 x 10-3 4.57 x 10-3 3.96 x 10-3 2.09 x 10-3 2.60 x 10-3 10 8.66 x 10-3 8.54 x 10-3 8.07 x 10-3 10.18 x 10-3 8.44 x 10-3 4.14 x 10-3 3.85 x 10-3 2.40 x 10-3 6.19 x 10-3 a Stations 11-13 excluded from th is appendix. The calculated ionic strength is based on a ca lculated Carbonate Alkalinity (CA). Since CA is a minor constituent in seawater, it c annot be calculated for Stations 1113 which exhibit seawater like characterisitics.

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52 Appendix V – Cation concentrations in the Hillsborough River (M) Station # Cations 09/19/1999 10/23/ 199911/21/199912/20/199901/20/2000 02/ 21/200003/20/200004/17/200006/20/2000 1 Na K Mg Ca 296.2 14.32 149.4 1661.8 278.8 11.77 148.1 1645.8 276.8 8.87 152.3 1648.1 282.4 13.69 155.4 1670.0 238.7 9.15 127.4 1345.2 288.3 11.99 158.9 1717.2 280.6 12.34 155.5 1688.2 214.6 7.34 118.6 1279.9 282.7 9.46 148.5 1304.5 2 Na K Mg Ca 1400.2 235.6 223.0 873.1 1415.0 235.8 256.7 995.3 3260.8 526.5 348.8 1491.8 NANA NANA 2260.7 242.7 339.5 1025.4 5470.2 767.6 339.4 1415.9 3 Na K Mg Ca 345.8 39.9 153.5 1173.5 503.3 57.0 197.90 1480.86 515.64 57.1 201.7 1569.2 975.0 133.5 191.8 1277.6 332.7 36.4 141.3 1104.4 513.7 57.7 201.7 1569.3 302.7 17.5 191.1 1595.0 711.7 74.27 216.4 1625.8 242.7 9.72 179.0 1278.3 4 Na K Mg Ca 636.8 81.3 186.8 1263.8 511.5 70.6 170.3 1074.4 523.1 64.8 193.2 1329.5 589.7 57.0 199.6 1409.4 41.0a 5.13a 14.4a 114.6a 666.2 60.1 203.8 1519.5 294.3 18.7 192.2 1587.0 294.9 16.7 186.6 1541.2 247.1 9.97 182.3 1361.1 5 Na K Mg Ca 735.5 95.7 198.7 1334.7 552.4 69.6 193.8 1310.2 549.2 69.7 207.9 1430.6 388.0 36.8 163.4 1234.2 580.0 68.4 195.1 1460.1 498.5 58.3 193.4 1436.4 298.2 19.3 192.8 1583.3 305.9 18.1 186.6 1537.1 249.7 11.0 183.1 1404.3 6 Na K Mg Ca 460.6 55.5 169.9 1259.0 579.8 76.7 190.1 1245.6 417.4 54.1 165.2 1133.4 458.9 48.4 219.5 1596.5 529.2 54.2 207.3 1533.9 537.2 63.1 212.0 1603.8 324.5 26.0 199.2 1599.2 297.4 19.6 184.8 1507.0 239.7 13.3 220.5 1305.7 7 Na K Mg Ca 468.0 56.8 184.3 1358.9 566.3 78.8 178.2 1191.2 513.4 66.7 200.3 1360.8 462.4 47.1 196.0 1492.1 447.7 45.3 177.8 1305.3 585.6 67.9 211.1 1593.4 329.7 26.8 194.7 1546.3 258.2 15.9 158.8 1322.1 241.4 15.9 214.8 1260.8 8 Na K Mg Ca 40.5a 6.14a 13.6a 97.3a 257.5 36.1 78.2 521.0 535.0 71.4 201.1 1342.2 469.2 50.3 199.3 1492.3 353.5 34.7 146.5 1083.6 537.9 60.8 209.1 1567.2 350.5 27.9 201.8 1569.7 320.1 19.7 190.3 1169.7 234.9 16.9 211.5 1305.2

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53 Appendix V – Cation concentrations in the Hillsborough River (M) (continued) Station # Cations 09/19/1999 10/23/ 199911/21/199912/20/199901/20/2000 02/ 21/200003/20/200004/17/200006/20/2000 9 Na K Mg Ca 521.1 73.2 164.6 1160.2 485.4 68.6 157.6 1033.2 571.5 77.4 200.9 1330.0 484.9 51.8 204.7 1508.6 497.2 47.6 205.7 1532.7 507.2 56.8 211.2 1562.7 243.4 17.9 138.9 1056.9 286.2 19.7 172.7 1341.4 239.2 16.9 204.1 1318.2 10 Na K Mg Ca 534.6 80.8 158.8 1086.1 533.2 80.8 176.5 1131.3 562.1 63.3 257.1 1598.3 525.7 54.3 261.1 1631.6 563.1 54.5 273.1 1752.1 529.3 45.8 208.8 1263.5 1183.7 43.1 307.0 1497.3 2031.6 57.5 435.9 1897.7 2590.3 64.7 197.5 1547.0 11 Na K Mg Ca NA 60157.2 1253.3 6624.2 4815.6 NANANA NANANA 121053.9 2506.5 13700.9 3942.3 12 Na K Mg Ca 82384.5 1739.2 9339.6 4641.0 90040.1 1867.1 10203.7 4616.0 NANANA NANANA 171598.1 3529.6 20242.8 5040.2 13 Na K Mg Ca 189867.1 3989.9 20983.3 5564.2 344022.6 7596.2 32503.6 8358.7 NANANA NANANA 315227.2 6496.5 28224.7 7734.9 a Data not included in mean calc ulations due to unreliability.

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54 Appendix V – Cation concentrations in the Hillsborough River (M) (continued) Station # Cations 07/24/2000 08/ 22/2000 10/04/2000 01/30/2001 05/02/20 01 06/25/2001 08/27/2001 09/13/2001 1 Na+ K+ Mg2+ Ca2+ 313.9 18.72 147.8 1499.0 323.9 11.64 156.9 1589.2 293.8 9.69 147.1 1527.1 298.3 16.13 167.4 1868.7 385.9 14.7 176.5 1685.8 314.4 12.02 160.5 1550.8 288.3 73.85 149.8 930.8 175.9 72.86 105.9 634 2 Na+ K+ Mg2+ Ca2+ 1965.7 270.9 262.4 1005.5 1511.5 241.3 262.3 1012.3 1594.4 274.6 271.3 1024.8 993.4 208.3 342.5 1231.6 830.2 142.3 245.6 811.7 5352.5 960.7 386.9 1397.8 1892.2 326.8 321.3 1306.9 1229.0 237.7 251.6 887.5 3 Na+ K+ Mg2+ Ca2+ 675.9 90.28 211.7 1478.6 696.2 102.5 223.5 1442.1 564.2 80.9 210.9 1425.5 323.1 19.18 190.0 1585.9 351.6 21.68 213.7 1700.7 748.6 108.7 213.3 1546.2 603.7 99.83 202.4 1302.1 404.8 102.1 154.8 897.6 4 Na+ K+ Mg2+ Ca2+ 602.0 72.43 213.9 1556.7 776.9 105.5 283.2 1689.7 501.1 72.3 183.8 1116.0 323.7 18.39 198.5 1627.0 421.8 34.79 222.2 1699.3 701.9 93.39 212.4 1593.7 566.1 103.5 190.6 1130.5 538.4 105.2 159.5 749.5 5 Na+ K+ Mg2+ Ca2+ 676.6 82.31 200.6 1420.1 768.2 106.0 305.3 1893.7 577.6 85.41 213.0 1337.2 315.7 16.36 197.6 1623.9 450.4 39.7 223.5 1684.9 763.1 103.4 210.2 1562.7 562.9 102.4 179.9 1107.1 473.6 92.77 155.5 984.4 6 Na+ K+ Mg2+ Ca2+ 736.8 91.34 249.9 1608.4 651.2 92.47 226.0 1503.4 614.4 88.28 203.8 1330.1 284.8 17.32 266.3 1855.0 448.0 39.96 319.8 2014.6 518.9 63.4 365.2 2125.9 534.3 101.7 172.1 1086.2 415.3 80.83 134.5 915.5 7 Na+ K+ Mg2+ Ca2+ 591.3 76.85 240.8 1641.0 696.2 85.99 286.3 2112.4 600.0 86.91 173.3 1270.4 289.1 17.28 267.6 1831.2 514.1 48.05 327.6 2073.4 279.6 24.47 358.3 2082.0 552.8 106.3 175.8 1165.8 NA 8 Na+ K+ Mg2+ Ca2+ 346.7 35.67 233.1 1629.4 672.9 84.26 280.9 2048.2 594.1 89.15 173.3 1227.2 292.1 18.48 281.7 1866.1 536.8 53.02 314.8 1987.8 263.5 20.3 328.0 1940.2 531.3 105.7 171.4 1128.2 408.3 76.95 133.0 1005.9

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55 Appendix V – Cation concentrations in the Hillsborough River (M) (continued) Station # Cations 07/24/2000 08/ 22/2000 10/04/2000 01/30/2001 05/02/20 01 06/25/2001 08/27/2001 09/13/2001 9 Na+ K+ Mg2+ Ca2+ 352.3 39.59 230.3 1598.1 646.2 89.65 253.7 1850.3 591.3 90.09 174.9 1241.5 234.0 15.10 223.1 1424.4 556.3 56.03 308.8 1964.9 247.1 20.9 311.9 1839.9 516.2 104.5 167.6 1099.9 401.3 75.23 132.9 982.0 10 Na+ K+ Mg2+ Ca2+ 1820.6 76.59 375.5 1575.7 851.9 75.27 285.7 1733.7 576.6 92.06 173 1257.9 637.2 29.17 342.2 1933.0 1671.4 76.39 424.2 2055.3 1108.7 38.13 393.2 1721.6 439.0 99.39 148.0 1004.7 289.2 76.43 127.2 979.5 11 Na+ K+ Mg2+ Ca2+ 85982 1903 9771 2786 44364 809 5016 3303 18011.5 407.4 1857.6 2124 516.26 1713 9589 4301 NANANANA 12 Na+ K+ Mg2+ Ca2+ 189185 4043 21448 5073 66013 1330 7596 3490 40190 748 3491 1050 175685 3740 20208 5966 NANA NANA 13 Na+ K+ Mg2+ Ca2+ 376570 8104 42782 8728 260741 5678 30670 7152 159167 3480 17511 3937 373463 8199 42846 9379 NANANANA

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56 Appendix V – Cation concentrations in the Hillsborough River (M) (continued) Station # Cations 09/19/2001 11/19/2001 1 Na+ K+ Mg2+ Ca2+ 129.1 75 83.93 556.0 322.4 21.9 170.7 1722.1 2 Na+ K+ Mg2+ Ca2+ 321.8 129.4 141.9 438 2305.7 359.7 326.9 1461.3 3 Na+ K+ Mg2+ Ca2+ 186.3 82.79 99.2 480.0 498.8 50.57 201.5 1593.5 4 Na+ K+ Mg2+ Ca2+ 323.4 94.56 125.0 456.4 648.4 68.39 181.2 1226.6 5 Na+ K+ Mg2+ Ca2+ 199.3 79.1 85.2 452.9 630.9 70.39 208.9 1515.4 6 Na+ K+ Mg2+ Ca2+ NA NA NA NA 563.5 61.99 198.7 1438.7 7 Na+ K+ Mg2+ Ca2+ 208.8 72.17 75.06 536.9 520.1 64.94 207.1 1481.5

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57 Appendix V – Cation concentrations in the Hillsborough River (M) (continued) Station # Cations 09/19/2001 11/19/2001 8 Na+ K+ Mg2+ Ca2+ 201.7 69.91 73.59 481.6 487.6 58.77 186.9 1317.9 9 Na+ K+ Mg2+ Ca2+ 209.7 71.09 76.1 503.3 572.6 68.82 211.8 1486.8 10 Na+ K+ Mg2+ Ca2+ 243.8 79.64 87.08 573.4 571.9 74.5 227.9 1512.4 11 Na+ K+ Mg2+ Ca2+ 2147.7 99 284.8 993.8 74656 1589 8354 4520 12 Na+ K+ Mg2+ Ca2+ 2756.5 102.7 345.1 984.4 85957 1859 9572 4320 13 Na+ K+ Mg2+ Ca2+ 54736 1295 6537 2372 219481 4667 24859 6176

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58 Appendix VI – Anion concentrations in the Hillsborough River (M) Station # Anions 06/20/2000 07/24/ 200008/22/200005/02/200106/25/2001 08/ 27/200109/13/200109/19/200111/19/2001 1 F12.97 17.36 18.83 12.11 3. 68 11.14 10.60 6.91 11.18 Cl281.0 269.3 281.7 324.1 294. 8 291.2 185.5 131.2 310.6 NO3 NA NA NA ND 9.03 27.43 9.14 ND 15.62 SO4 2178.7 168.7 179.4 231.9 227. 2 84.63 70.75 42.05 168.2 CAa 2542.4 2997.5 3163.5 3322.2 2984. 1 2003.0 1368.3 1239.5 3452.2 2 F27.13 31.19 27.26 23.68 24. 21 34.64 19.53 13.23 ND Cl3976.5 1498.3 1092.8 688.9 3533. 2 1357.8 972.7 316.0 1720.1 NO3 NA NA NA 23.55 32. 58 33.87 35.95 4.23 51.08 SO4 21915.6 424.2 360.6 193.5 1669. 7 595.3 379.5 118.0 610.2 CAa 1893.1 2373.5 2439.7 1942.1 2939. 0 2836.0 1930.7 1002.1 3237.2 3 F9.09 79.96 20.76 7.89 4.74 13.01 13 9.91 8.5 Cl303.3 567.7 563.4 332.9 608. 7 496.7 365.6 197.3 445.0 NO3 NA NA NA 112.6 99. 35 67.96 32.88 7.28 98.74 SO4 2105.5 256.8 219.6 127.0 257. 7 214.7 144.8 66.8 174.9 CAa 2640.4 2970.8 3091.6 3491.7 3142. 0 2690.8 1891.3 1053.6 3233.5 4 F8.82 78.69 20.86 7.89 2. 63 17.67 16.53 15.03 11.75 Cl303.7 528.4 666.6 373.2 586. 2 537.2 534.4 359.3 678.7 NO3 NA NA NA 72.90 74.19 24.45 0 0 55.16 SO4 2109.5 358.9 753.9 155.8 261. 0 174.8 165.3 126.5 208.4 CAa 2809.6 2875.1 2617.2 3530.1 3218. 5 2363.0 1560.8 936.9 2362.9

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59 Appendix VI – Anion concentrations in the Hillsborough River (M) (continued) Station # Anions 06/20/2000 07/24/ 200008/22/200005/02/200106/25/2001 08/ 27/200109/13/200109/19/200111/19/2001 5 F9.54 79.38 21.92 12.11 2. 63 20.48 17.15 12.71 11.65 Cl300.8 573.6 630.2 414.7 633. 6 545.3 443.3 196.1 556.8 NO3 NA NA NA 62.10 65.00 17.5 8.71 0 52.3 SO4 2109.6 243.5 990.2 172.0 278.4 145 140.7 75.23 201 CAa 2903.1 2845.4 2624.7 3469.8 3149. 7 2344.8 2075.5 974.0 3119.6 6 F10.06 80.36 19.23 8.42 7. 37 17.91 4.59 NA 12.44 Cl278.8 605.9 565.9 390.4 485. 5 535.5 137.6 NA 544.8 NO3 NA NA NA 60.97 33. 06 8.10 0.00 NA 37.68 SO4 2345.9 522.6 784.1 167.1 1001. 6 144.0 41.70 NA 225.6 CAa 2322.5 2803.2 2039.1 4359.1 3031. 6 2281.6 2358.3 NA 2846.5 7 F10.32 79.42 20.43 10.53 57. 89 20.06 NA 9.65 12.15 Cl280.1 527.9 598.3 434.4 322. 4 527.5 NA 232.5 516.4 NO3 NA NA NA 24.52 24.84 ND NA ND 21.32 SO4 2326.1 625.5 1512.4 772.4 938. 8 140.2 NA 69.54 198.6 CAa 2264.7 2562.9 1925.5 3346.6 2897. 9 2494.9 NA 1115.5 550.6 8 F10.41 78.67 20.69 10.53 49. 47 27.8 11.74 9.57 12.48 Cl278.4 384.2 616.3 453.6 306. 9 514.6 404.4 215.6 516.3 NO3 NA NA NA 18.87 29.84 ND ND ND 23.22 SO4 2349.5 520.4 1568.2 675.1 878. 1 138.0 133.8 67.22 224.4 CAa 2295.8 2590.8 1629.1 3357.3 2674. 7 2397.7 2068.7 1010.3 374.2 9 F10.41 77.98 19.8 10.53 16. 32 16.95 11.65 9.6 12.19 Cl285.7 392.2 596.4 476.5 289. 1 502.7 401 219.4 492.9 NO3 NA NA NA 0.00 24.68 ND ND ND 21.58 SO4 2305.5 618.1 1321.9 678.5 816. 2 137.5 134.0 68.91 213.5 CAa 2391.0 2327.9 1669.5 3312.0 2604. 3 2339.2 2014.9 1060.2 841.9

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60 Appendix VI – Anion concentrations in the Hillsborough River (M) (continued) Station # Anions 06/20/2000 07/24/ 200008/22/200005/02/200106/25/2001 08/ 27/200109/13/200109/19/200111/19/2001 10 F11.69 80.34 22.1 13.16 12. 63 14.37 10.9 11.94 12.8 Cl3282.2 2163.3 864.3 1929.5 1348. 7 412.7 389.2 236.8 554.0 NO3 NA NA NA 0.00 0.00 0 0 0 0 SO4 2775.1 783.0 1083.2 997.1 943. 7 140.9 156.2 93.91 316.7 CAa 1298.1 1984.5 1907.7 2767.0 2126. 3 2113.3 1860.1 1194.8 2921.6 11 FNA NA NA NA NA NA NA NA NA ClNA 129064 41738 NA NA NA NA 2291.8 83979 NO3 NA NA NA NA NA NA NA NA NA SO4 2NA 7276 3860 NA NA NA NA 287.3 6140 12 FNA NA NA NA NA NA NA NA NA Cl214600 239341 63324 NA NA NA NA 3400.8 103700 NO3 NA NA NA NA NA NA NA NA NA SO4 210909 11946 4733 NA NA NA NA 388.7 6748 13 FNA NA NA NA NA NA NA NA NA Cl345024 468696 296577 NA NA NA NA 47393 332839 NO3 NA NA NA NA NA NA NA NA NA SO4 216044 21563 14405 NA NA NA NA 2460 16058 a CA (carbonate alkalinity) is calcul ated from charge balance (CA = [HCO3 -] + 2[CO3 2-]), and at typical river pH [HCO3 -]>>[CO3 -]. b CA not calculated for Stations 11-13. Since CA is a minor co nstituent in seawater, it cannot be calculated for Stations 11-13 which exhibit seawater like characterisitics.

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61 Appendix VII – PO4 concentrations in the Hillsborough River (M) Station # 09/19/1999 10/ 23/1999 11/21/1999 12/20/1999 01/ 20/2000 02/21/2000 03/20/2000 04/ 17/2000 05/22/2000 06/20/2000 1 1.63 3.48 1.22 1.55 0.81 3.67 2.12 2.06 2.12 2.87 2 13.40 14.00 9.11 10.78 11.70 11.11 15.53 13.07 15.45 13.66 3 4.16 4.62 2.50 4.77 1.77 2.04 2.19 3.52 1.57 2.12 4 6.04 5.45 3.30 3.00 2.21 3.12 2.65 1.95 1.75 1.76 5 6.32 5.97 3.77 3.34 2.50 3.07 2.96 2.26 2.21 1.86 6 5.18 6.19 3.69 3.60 2.65 3.07 2.86 2.15 0.27 1.52 7 4.80 6.40 3.34 2.87 2.64 2.66 2.58 1.24 0.16 0.75 8 5.14 6.84 3.57 2.89 2.55 2.46 2.54 1.37 0.86 0.96 9 5.65 6.71 3.91 2.86 2.72 2.27 2.46 1.73 2.71 1.70 10 5.73 6.06 0.21 1.25 0.59 0.07 1.21 1.53 2.05 1.12 11 3.83 4.75 3.57 3.99 3.18 3.34 6.91 5.38 6.67 8.80 12 4.55 5.35 3.87 4.40 2.84 3.10 7.49 5.25 8.65 8.55 13 6.42 6.40 4.22 4.47 3.33 4.03 5.66 4.55 5.43 7.05

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62 Appendix VII – PO4 concentrations in the Hillsborough River (M) (continued) Station # 07/24/2000 08/ 22/2000 10/04/2000 01/30/2001 05/ 02/2001 06/25/2001 08/27/2001 08/ 30/2001 09/04/2001 09/08/2001 1 3.17 3.24 1.90 1.70 1.87 2.05 14.25 16.49 12.77 10.65 2 18.97 14.04 13.10 10.99 14.59 9.53 15.04 18.88 14.70 12.55 3 7.69 9.86 6.52 0.80 2.13 4.07 10.60 8.16 5.97 10.83 4 4.34 10.48 8.43 0.91 2.67 2.65 13.16 11.94 9.72 8.53 5 5.03 10.00 9.31 0.94 2.90 3.11 14.20 14.33 11.21 10.47 6 5.24 6.77 9.46 1.04 2.34 2.65 14.20 14.47 11.77 4.45 7 4.77 7.11 7.40 0.62 2.23 2.65 12.91 13.38 11.65 6.02 8 3.08 8.59 8.00 0.40 2.84 2.10 13.57 14.91 12.44 7.18 9 3.42 9.67 8.41 0.37 2.51 3.26 14.52 14.74 13.11 8.18 10 1.89 3.67 7.36 0.04 1.91 0.90 14.43 15.41 12.77 12.18 11 5.72 4.70 4.83 3.31 NA NA NA NA NA NA 12 7.80 4.62 6.24 4.25 NA NA NA NA NA NA 13 8.32 5.83 6.67 3.28 NA NA NA NA NA NA

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63 Appendix VII – PO4 concentrations in the Hillsborough River (M) (continued) Station # 09/13/2001 09/19/2001 11/19/2001 1 9.73 14.84 2.63 2 17.96 26.28 8.71 3 12.84 17.31 2.61 4 12.94 11.02 4.89 5 13.40 14.19 4.94 6 8.12 NA 5.22 7 NA 5.51 4.92 8 7.03 7.99 4.58 9 7.13 8.36 4.57 10 7.14 8.77 3.60 11 NA 6.17 4.55 12 NA 5.06 4.41 13 NA 4.77 4.50

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64 Appendix VIII – Calculated (Saturation State) Values (as log ) Station # 05/22/2001 06/25/2001 08/27/2001 09/19/2001 11/19/2001 1 0.148 0.159 -0.724 -1.425 0.084 2 -0.392 0.333 -0.188 -1.682 0.034 3 0.671 0.450 -0.155 -1.394 0.292 4 0.848 0.644 -0.774 -1.749 -0.314 5 0.855 0.586 -0.790 -1.941 -0.015 6 0.945 0.543 -0.835 NA -0.115 7 0.733 0.483 -0.873 -1.644 -0.748 8 0.668 0.431 -0.859 -1.714 NA 9 0.706 0.287 -0.873 -1.632 -0.604 10 0.461 0.938 -0.649 -1.344 0.444