Collaborative Research: Hydrology and Geochemistry of Prairie Pothole Lake Sedimentary Pore Waters: Implications for the Attenuation of Pesticides

智力优势：草原壶穴湖（PPL也称为湿地）是上中西部冰碛物的重要水文特征。该地区的水文和气候以及冰碛物的组成形成了PPL特有的水化学，包括极高水平的硫酸盐。由NSF资助的一个试点项目的结果表明，硫酸盐在沉积物中发生还原，产生mM水平的还原硫物质。我们的数据表明，从棉白杨湖区的P1和P8湖采样的未改变的PPL孔隙沃茨，无生物活性，迅速降解氯乙酰苯胺和硝基芳香族农药（这是大量使用的行作物农业在该地区）。此外，我们发现溶解有机物水平在100毫克/升-C的孔隙沃茨，这是最高的湖泊系统测量。这项建议扩大了我们以前的工作，了解水文学之间的联系，PPL孔隙沃茨的独特的地球化学组成的演变，其能力，以减弱农药。我们假设，在当地水文响应干旱，蒸散和降水的变化可以影响能够衰减农药的化学物种的组成和丰度。我们的具体假设是：1）。在干旱期间，蒸散是地下水流出PPL的重要驱动力; 2）。大量的降水造成地下水土丘，可以扭转水力梯度，导致地下水回流到湿地; 3）。PPLs的地球化学组成受这些局部和季节性变化的水文过程的影响; 4）。漫流能够将农药和其他化学成分输送到PPL;以及5）。PPL孔隙水成分能够衰减其他类别的常用农药超出试点项目中研究的。草原坑洼湖是一个重要的水文和生态特征，具有国家和国际重要性（例如，地下水补给、水禽和其他动物的栖息地等）。其独特的水化学特性使其成为减轻这一广泛耕种地区使用的农药影响的重要手段。我们的研究可能会影响这些湖泊在未来的管理，特别是在非点源农业污染的棘手问题。拟议的研究将支持三名研究生，他们将负责进行研究并帮助我们的USGS同事。学生将协调合作大学和USGS实验室之间的研究和采样活动。研究成果将通过会议、期刊出版物和与当地利益攸关方举行的非正式全体会议广泛传播。将通过面向非住宿夏令营的活动，向科学和工程领域代表性不足的高中生进行宣传。此外，我们建议招聘一名高中教师陪同我们进行抽样旅行，并通过电子期刊和在他/她的课堂上分享这些经验。这一外联举措是基于NSF资助的ARCUS TREC模型。

Intellectual Merit: Prairie pothole lakes (PPLs also referred to as wetlands) are important hydrologic features in the glacial till of the Upper Midwest. The hydrology and climate of the region coupled with the composition of the till have developed water chemistries unique to PPLs, including extremely high levels of sulfate. Results of a pilot project funded by NSF showed that sulfate undergoes reduction in the sediments to produce reduced sulfur species in the mM levels. Our data demonstrated that unaltered PPL pore waters sampled from lakes P1 and P8 in the Cottonwood Lakes Area abiotically and rapidly degraded chloroacetanilide and nitroaromatic pesticides (which are heavily used in row crop agriculture in the region). Additionally, we found dissolved organic matter levels in the 100s of mg/L-C in the pore waters, which are among the highest measured for lacustrine systems. This proposal expands upon our previous work to understand the linkages between hydrology, the evolution of the unique biogeochemical composition of PPL pore waters, and its ability to attenuate agricultural pesticides. We hypothesize that changes in the local hydrology in response to drought, evapotranspiration, and precipitation can influence the composition and abundance of chemical species capable of attenuating pesticides. Our specific hypotheses are: 1). During periods of drought, evapotranspiration is an important driver of groundwater flow out of PPLs; 2). Extensive precipitation creates water table mounds that can reverse hydraulic gradients and cause groundwater to flow back into wetlands; 3). The biogeochemical composition of PPLs is influenced by these local and seasonally varying hydrologic processes; 4). Overland flow is capable of transporting both pesticides and other chemical constituents to PPLs; and 5). PPL pore water constituents are capable of attenuating other classes of commonly used pesticides beyond those studied in the pilot project. Prairie pothole lakes are a critical hydrological and ecological feature of national and international importance (e.g., groundwater recharge, habitats for waterfowl and other fauna, etc.). Their unique water chemistry makes them an important means for mitigating the effects of pesticides used in this extensively farmed region. Our research could influence how these lakes are managed in the future, especially with respect to the intractable problem of nonpoint source agricultural pollution. The proposed research will support three graduate students who will be responsible for conducting the research and aiding our USGS colleagues. The students will coordinate research and sampling events between the collaborating universities and the USGS laboratories. Research results will be broadly disseminated through conferences, journal publications, and informal town hall meetings with local stakeholders. Outreach to high school students from underrepresented groups in science and engineering will occur through activities oriented non-residential summer camps. Further, we propose to recruit a high school teacher to accompany us on our sampling trips and share these experiences through electronic journals and in his/her classroom. This outreach initiative is based upon the NSF funded ARCUS TREC model.