DISSERTATION RESEARCH: Mercury Bioavailability and its Environmental Controls in a River Network

汞是一种全球性污染物，通过食用鱼类影响人类，并通过对野生物种的不利影响间接影响人类。汞的有机形式甲基汞是生物体最容易获得的形式，因此甲基汞的生成是决定汞在水生生态系统中生物累积的最关键因素。然而，人们对溪流和河流中甲基汞生产的生态系统控制知之甚少。拟议的研究将调查率和潜在的机制介导甲基汞生产通过丝状藻类，这可能是作为？热点？汞在河流中的快速转化具体而言，这项研究将审查甲基汞的生产是否与河流生态系统中丝状藻类的生长阶段有关，在河流生态系统中，水文，食物网关系和生态系统过程的特点是从以前的研究。通过测量原位汞甲基化率和操纵微生物和光合作用的活动，这项研究将阐明介导丝状藻类在自然河流中汞转化中的作用的关键生态因素。该项目整合了不同的科学学科，以了解一个高度复杂的环境问题-汞污染的生态系统调解。拟议的工作将提供有关溪流和河流生态系统中汞循环的基本知识。这些新知识可能有助于预测水生食物网中汞的可得性变化，以应对森林砍伐和养分富集等土地利用方式改变的影响。此外，拟议的工作将通过实地样品收集和分析为研究生和本科生研究人员提供教育和研究机会。最后，这项拟议研究的结果将通过在科学会议上的介绍和在同行评审的期刊上发表而广泛传播。

Mercury is a global contaminant that affects humans through fish consumption and indirectly through adverse effects on wildlife species. The organic form of mercury, methylmercury, is the most readily available form to the organisms making the production of methylmercury the most critical factor determining mercury bioaccumulation in aquatic ecosystems. The ecosystem controls of methylmercury production in streams and rivers are poorly understood, however. The proposed research will investigate the rates and potential mechanisms mediating methylmercury production via filamentous algae, which may be functioning as ?hotspots? of rapid mercury transformations in rivers. Specifically, this research will examine whether the production of methylmercury is related to the growth stages of filamentous algae in a river ecosystem where hydrology, food web relationships and ecosystem processes are well characterized from previous studies. By measuring in-situ mercury methylation rates and manipulating both microbial and photosynthetic activities, this research will elucidate key ecological factors that mediate the role of filamentous algae in mercury transformations in natural rivers. The project integrates different scientific disciplines toward understanding a highly complex environmental issue - ecosystem mediation of mercury contamination. The proposed work will provide fundamental knowledge regarding the cycling of mercury in stream and river ecosystems. The new knowledge may allow the prediction of changes in availability of mercury to aquatic food webs in response to effects of altered land use such as forest clearing and nutrient enrichment. In addition, the proposed work will provide educational and research opportunities for a graduate student and undergraduate researchers through field sample collection and analyses. Lastly, the results from this proposed study will be widely disseminated through presentations in scientific meetings and publication in peer-reviewed journals.