Biogeochemistry of Dissolved Organic Matter in Pony Lake, Ross Island

Abstract: Dissolved organic matter (DOM) is a significant chemical component in aquatic systems because it acts as an important carbon source for microorganisms, absorbs harmful radiation in sunlight, is able to complex metals, and can participate in important biogeochemical reactions. This study will investigate the biogeochemical cycling of DOM in a small coastal Antarctic pond, Pony Lake, located on Cape Royds, Ross Island. Because there are no higher plants present at this site all of the DOM in this lake is derived from microorganisms. Thus, Pony Lake is an ideal site to study the effect of physical, chemical, and microbial processes on the composition and character of the DOM pool. Finally, Pony Lake is also an ideal site to collect an International Humic Substances Society (IHSS) fulvic acid standard. Unlike other IHSS standards, this standard will not contain DOM components derived from higher land plants. To better understand the role of physical influences, the project will study the changes in the DOM pool as the lake evolves from ice-covered to ice-free conditions during the summer, as well as the relationship of DOM to the observed turnover of dominant microbial communities in the lake. Scientists will also monitor changes in microbial abundance, diversity, and productivity that may occur during the ice to open-water transition period. This research will provide much needed information regarding the relationship between microbial diversity and DOM biogeochemistry. Middle school science students will be active participants in this project through the Internet, while scientists are in the field, and in the lab.摘要：溶解性有机物（Dissolved Organic Matter, DOM）是水生生态系统中的重要化学组分，可作为微生物的关键碳源、吸收太阳光中的有害辐射、可与金属离子络合并参与重要的生物地球化学反应。本研究将对位于罗斯岛罗伊兹角的南极小型沿海池塘小马湖（Pony Lake）中DOM的生物地球化学循环展开调查。由于该区域无高等植物分布，该湖泊内所有DOM均源自微生物，因此小马湖是研究物理、化学及微生物过程对DOM库组成与特征影响的理想场所。此外，小马湖也是采集国际腐殖物质学会（International Humic Substances Society, IHSS）黄腐酸标准样品的理想位点：与其他IHSS标准样品不同，该标准样品不会包含源自陆地高等植物的DOM组分。为进一步明晰物理因素的调控作用，本项目将研究夏季湖泊从冰封转为无冰状态过程中DOM库的变化，以及DOM与湖泊中优势微生物群落周转的关联。研究人员还将监测冰盖消融至开放水体过渡期内微生物丰度、多样性及生产力的变化。本研究将为微生物多样性与DOM生物地球化学之间的关联提供亟需的研究资料。在科研人员赴野外开展工作及进行实验室实验期间，中学科学课程学生将通过互联网深度参与本项目。