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

知识价值：草原坑坑湖(又称湿地)是中西部上半部冰川冰川地带的重要水文特征。该地区的水文和气候，再加上收银机的成分，形成了PPLS所特有的水化学，包括极高水平的硫酸盐。由国家科学基金会资助的一个试验项目的结果表明，硫酸盐在沉积物中经历还原，产生毫米级的还原硫物种。我们的数据表明，从棉铃湖地区的P1和P8湖采集的未改变的PPL孔隙水非生物地和快速地降解了氯乙酰苯胺和硝基芳香族农药(这两种农药在该地区的行作物农业中大量使用)。此外，我们还发现孔隙水中的溶解有机质含量在mg/L-C的100s左右，这是湖相系统测得的最高水平之一。这项建议扩展了我们以前的工作，以了解水文学、PPL孔隙水独特的生物地球化学成分的演变以及其减弱农业杀虫剂的能力之间的联系。我们假设，当地水文因干旱、蒸散和降水而发生的变化可以影响能够减弱杀虫剂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PPLs的重要驱动因素；2)。大量降水会形成地下水位丘，可能会逆转水力梯度，导致地下水回流到湿地；3)PPLs的生物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；陆上流动能够将杀虫剂和其他化学成分输送到PPLS；以及5)。PPL孔隙水成分能够减弱试验项目中所研究的其他类别的常用杀虫剂。草原坑坑湖是具有国家和国际重要性的重要水文和生态特征(例如，地下水补给、水禽和其他动物的栖息地等)。它们独特的水化学使它们成为减轻这个广泛耕种地区使用的杀虫剂影响的重要手段。我们的研究可能会影响未来这些湖泊的管理方式，特别是在面源农业污染这一棘手问题上。这项拟议的研究将支持三名研究生，他们将负责开展研究并帮助我们的USGS同事。学生们将协调合作大学和美国地质调查局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市政厅会议广泛传播。将通过面向活动的非寄宿夏令营，向科学和工程专业代表性不足群体的高中生开展外联活动。此外，我们建议聘请一名高中教师陪同我们的抽样旅行，并通过电子期刊和他/她的课堂分享这些经验。这项外展计划是基于美国国家科学基金会资助的ARCUS TREC模式。

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.