Dissertation Research: Nitrogen to phosporus ratio as a driver of arsenic retention

砷是一种微量元素，可能对人体有毒，浓度较低时会引起神经系统症状或具有免疫和内分泌效应。纵观历史，砷被用作毒药、杀虫剂和武器，它污染了超过10亿人的食物和水源。此外，世界各地许多地下水泉水中天然存在的砷含量超过了人类饮用水的安全水平。随着地下水渗入河流，砷含量的升高会影响河流的化学和生物学。这项博士论文改进补助金（DDIG）研究将砷整合到厄瓜多尔正在进行的溪流研究中，以评估是什么驱动了溪流植物和动物中的砷保留，以及如何影响砷的下游运输。了解砷如何与其他元素相互作用，在供水中循环，将为全球减缓工作提供信息。此外，研究人员将向依赖砷污染沃茨的厄瓜多尔社区传播研究结果。溪流砷浓度升高可通过改变氮磷的生态地球化学循环或通过改变水生食物网来改变溪流生态系统功能。此外，砷对水生食物网的生物利用度和影响与水生系统中氮和磷的浓度以及氮磷比密切相关。该奖项的资金将用于评估河水的氮磷比如何影响地热流中砷的保留和运输，其中氮磷比不同。这项研究还将测试溪流资源氮磷比对水生食物网中砷循环的影响，以及砷的生物排泄和随后的下游运输。

Arsenic is a trace element that can be toxic to people and at lower concentrations cause neurological symptoms or have immunological and endocrine effects. Throughout history, arsenic has been used as a poison, pesticide, weapon, and it has contaminated more than a billion-people's food and water supplies. In addition, a number of groundwater springs worldwide have naturally occurring arsenic levels that exceed those safe for human drinking water. As this groundwater seeps into streams the elevated arsenic can affect the chemistry and biology of the stream. This Doctoral Dissertation Improvement Grant (DDIG) research integrates arsenic into an ongoing study of streams in Ecuador to assess what drives arsenic retention in stream plants and animals and how that affects the transport of arsenic downstream. Understanding how arsenic interacts with other elements to cycle through water supplies will inform global mitigation efforts. Furthermore, the researchers will disseminate results to Ecuadorian communities reliant on arsenic contaminated waters. Elevated stream arsenic concentrations can alter stream ecosystem function by altering the biogeochemical cycling of nitrogen and phosphorus or via altering aquatic food webs. In addition, the bioavailability and effects of arsenic on aquatic food webs are closely interlinked with both the concentrations of nitrogen and phosphorus and the ratio of nitrogen to phosphorus present in aquatic systems. Funds from this award will be used to evaluate how the nitrogen:phosphorus ratio of stream water affects the retention and transport of arsenic in geothermal streams with varying nitrogen:phosphorus ratios. The study also will test the effect of stream resource nitrogen:phosphorus ratio on arsenic cycling in the aquatic food web and biotic excreation of arsenic and consequent downstream transport.