Microbial Atrazine Breakdown in a Karst Groundwater System and Its Effect on Ecosystem Energetics

Citation

Material Information

Title:
Microbial Atrazine Breakdown in a Karst Groundwater System and Its Effect on Ecosystem Energetics
Series Title:
Journal of Environmental Quality
Creator:
Iker, Brandon C.
Kambesis, Pat
Oehrle, Stuart A.
Groves, Chris
Barton, Hazel A.
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Microbial Community ( local )
Subterranean Aquifers ( local )
Atrazine ( local )
Genre:
serial ( sobekcm )

Notes

Abstract:
In the absence of sunlight energy, microbial community survival in subterranean aquifers depends on integrated mechanisms of energy and nutrient scavenging. Because karst aquifers are particularly sensitive to agricultural land use impacts due to rapid and direct hydrologic connections for pollutants to enter the groundwater, we examined the fate of an exogenous pesticide (atrazine) into such an aquifer and its impact on microbial ecosystem function. Atrazine and its degradation product deethylatrazine (DEA) were detected in a fast‐flowing karst aquifer underlying atrazine‐impacted agricultural land. By establishing microbial cultures with sediments from a cave conduit within this aquifer, we observed two distinct pathways of microbial atrazine degradation: (i) in cave sediments previously affected by atrazine, apparent surface‐derived catabolic genes allowed the microbial communities to rapidly degrade atrazine via hydroxyatrazine, to cyanuric acid, and (ii) in low‐impact sediments not previously exposed to this pesticide, atrazine was also degraded by microbial activity at a much slower rate, with DEA as the primary degradation product. In sediments from both locations, atrazine affected nitrogen cycling by altering the abundance of nitrogen dissimulatory species able to use nitrogenous compounds for energy. The sum of these effects was that the presence of atrazine altered the natural microbial processes in these cave sediments, leading to an accumulation of nitrate. Such changes in microbial ecosystem dynamics can alter the ability of DEA to serve as a proxy for atrazine contamination and can negatively affect ecosystem health and water quality in karst aquifers.
Original Version:
Journal of Environmental Quality, Vol. 39, no. 2 (2010-03-01).

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.

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University of South Florida
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