Oxygen, Carbon and Phosphorus Flux from Lake Sediments: Regulation Through Epipelic Algae and Bacteria

研究了湖泊底质表面的藻类和细菌群落，即周围植物群落控制水-底质界面氧、碳、磷通量的途径。本研究主要围绕四个方面展开：1)阐明沉积物上覆水体磷通量昼夜波动的产生机制；2)在沉积物-水界面季节性变化条件下，确定藻类异养性和对缺氧条件的耐受性对维持藻类群落的重要性；3)沉积物-水界面生物和物理化学因子在控制湖泊缺氧动力学中的作用的识别和量化；4)确定了周边植物群落中藻类和细菌的各种营养来源。这项研究将在两个地点进行：一个是密歇根州的碱性湖劳伦斯湖；以及缅因州奥尔诺附近的酸性湖泊。最先进的系统将被用于隔离和操纵周生植物，允许改变光照水平和生长周生植物的“孔隙水”溶液的化学成分。通过计算机辅助微电极数据采集系统，将对沉积物和水柱之间的边界层的化学条件进行极其详细的测量。Klug博士的研究团队率先在湖泊生物地球化学研究中使用了该系统。本研究的意义在于关注湖泊的磷动态。磷被认为是导致许多湖泊和河流富营养化的营养物。了解控制这些水体中磷动态的因素显然对它们的管理很重要。克鲁格博士是湖泊生物地球化学研究领域的世界领导者。这项研究得到了机构的大力支持。生态系统研究项目建议授予该资助。

The ways in which the community of algae and bacteria, the periphyton community, at the sediment surface in lakes controls the fluxes of oxygen, carbon and phosphorus at the water-sediment interface will be studied. The research is organized around four tasks: 1) elucidation of the mechanisms involved in producing the day-night fluctuations of phosphorus afflux from the sediments to the overlying water; 2) determination of the importance of algal heterotrophy and tolerance of suboxic conditions in the maintenance of the algal community under the seasonally changing conditions present at the sediment-water interface; 3) identification and quantification of the roles of the biological and physiochemical factors at the sediment-water interface that are involved in the control of oxygen dynamics of lake hypolimnia; and 4) determination of the various sources of nutrients for the algae and bacteria of the periphyton community. The research will be conducted at two sites: an alkaline lake, Lawrence Lake, in Michigan; and an acidic lake in the vicinity of Orno, Maine. State-of-the-art systems will be used for the isolation and manipulation of periphyton that permits variations in light levels and the chemical composition of the "porewater" solutions in which the periphyton is grown. Extremely detailed measurements of chemical conditions at the boundary layer between sediment and the water column will be made with a computer-aided microelectrode data acquisition system. Dr. Klug's research team has pioneered in the use of this system in studies of lake biogeochemistry. The significance of this research is its focus on phosphorus dynamics of lakes. Phosphorus has been identified as the nutrient responsible for the euthrphication of many lakes and rivers. Understanding factors that control phosphorus dynamics in these water bodies is clearly important to their management. Dr. Klug is a world leader in the study of lake biogeochemistry. The institutional support for this research is outstanding. The Ecosystem Studies Program recommends award of this grant.