Collaborative Research: Microbial Mediation of Trace Metal Cycling in Four Stratified Antarctic Lakes

9814837 green8 .拟议的研究将检查微生物对麦克默多干谷四个分层湖泊中金属循环的影响：Fryxell湖、Hoare湖、Joyce湖和Miers湖。这些湖泊的特点是异常稳定的氧化还原过渡带，特别适合于精细间隔的采样制度。总的来说，它们代表了广泛的水化学成分。本研究将对以下假设进行检验：(1)水体中锰还原起始点与铁还原起始点存在明显的空间差异。重金属和稀土元素将与锰而不是铁共循环。(2)在所有四个湖泊中，锰的还原将与肉菌或其他锰还原生物的存在有关。简而言之，该研究将探索微生物活动与关键氧化还原边界上大量化学元素的循环和命运之间的联系。溶解和颗粒金属剖面将作为从冰水界面到沉积物的深度的函数进行检查。谱图将与微生物锰还原试验和锰还原剂的存在相关联，通过mn -氧化物覆盖琼脂板筛选和已知锰还原剂探针的核酸杂交检测。这项研究将包括本科生的大量参与。

9814837GREENThe proposed research will examine the role of microbial influences on metal cycling in four stratified lakes in the McMurdo Dry Valleys: Lake Fryxell, Hoare, Joyce and Miers. These lakes are characterized by unusually stable redox transition zones and are especially amenable to a finely spaced sampling regime. Collectively, they represent a broad range of water chemistries. The proposed research will test the following hypotheses: (1) Instratified water columns there will be a clear spatial difference between the onset of manganese reduction and the onset of iron reduction. Heavy metals and rare earth elements will be seen to undergo co-cycling with manganese rather than with iron. (2) In all four lakes, manganese reduction will be associated with the presence of carnobacteria or with other manganese-reducing organisms. In brief, the study will explore the link between microbial activity and the cycling and fate of a large suite of chemical elements at key redox boundaries. Dissolved and particulate metal profiles will be examined as a function of depth from the ice-water interface to the sediments. Profiles will be correlated with microbial manganese-reduction assays and the presence of manganese reducers as detected by screening with Mn-oxide overlay agar plates and nucleic acid hybridizations with probes for known manganese reducers. The research will include significant involvement of undergraduates.