Influence of Natural Reductants on the Abiotic Reduction of Pentachloronitrobenzene in Prairie Pothole Lakes
Keywords:Influence of Natural Reductants on the Abiotic Reduction of Pentachloronitrobenzene in Prairie Pothole Lakes
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. School of Earth Sciences Senior Theses; 2011
Nitroaromatic compounds such as pentachloronitrobenzene (C6Cl5NO2) were once widely used as fungicides and pesticides in the United States and some (trifluralin and pendamethilin) are still in circulation. These compounds can contaminate natural systems including surface waters and sediments through overland runoff. In this study, the abiotic reduction of PCNB was examined in controlled laboratory systems containing natural wetland pore waters collected from the Prairie Pothole Lakes (PPL) in North Dakota. The PPL region is dominated by agricultural land use, which can impact the water quality of the lakes due to overland runoff containing organic contaminates. High levels of dissolved organic matter (DOM) and possible reduced sulfur species in pore waters could make the PPL reactive towards organic contaminates entering the system. Reduction of pentachloronitrobenzene to pentachloroaniline was observed by reaction with natural reductants in PPL pore waters. Iron analysis of the natural pore waters revealed a Fe(II) concentration of 14 μM, which makes it a relatively unimportant reductant. Even when compared to high concentration Fe(II)-only controls , natural pore waters degraded pentachloronitrobenzene at a faster rate. This indicates that the degradation in natural pore waters possibly occurred by reaction with other electron donors such as bisulfide or polysulfides in the presence of dissolved organic matter. Future work is necessary to elucidate the nature of the reductant and the precise role of DOM in the reduction of pentachloronitrobenzene.
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