Collaborative Research: The Biogeochemistry of Dimethylsulfied (DMS) and Related Compounds in a Chemically Stratified Antarctic Lake

二甲基硫醚（DMS）是海洋排放的主要挥发性硫化合物，可能占海洋到空气生物硫通量的90%。据推测，与DMS氧化产物相关的凝结核引起的云形成可以直接抵消人为产生的CO2的变暖效应。尽管DMS和相关的磺化化合物在全球具有重要意义，水生系统在DMS生产中也发挥着重要作用（特别是在南极地区），但DMS和相关的磺化化合物的来源和汇仍然不明确。我们提议的多研究员实地和实验室研究将检查水柱和沉积DMS/DMSP（二甲基磺酰丙酸）的生物地球化学，以及相关化合物（如二甲基亚砜，二甲基化多硫化物）在邦尼湖的作用。邦尼湖是一个相对简单的水生系统（没有湍流，没有食草动物和很少的大气交换），因此为研究微生物介导的生物硫循环提供了一个高度可处理的环境。初步数据表明，DMS前体的最高水平出现在湖泊的深层叶绿素层，这是一个由隐生藻类主导的区域。此外，邦尼湖的无光水体中的DMS浓度是自然水体系统中最高的。这些观察结果表明，由滋养区浮游植物产生的前体沉降到失光水体和沉积物中，在那里它们被微生物分解成DMS和其他含硫化合物。拟议的研究将确定DMS和相关化合物的来源和汇，并将它们与整个生态系统功能联系起来。建立了邦尼湖有机硫化合物生物地球化学转化模型。

OPP 98-15998 P.I. J. PriscuOPP98-18140 P.I. G. DiTullioDimethylsulfide (DMS) is the dominant volatile sulfur compound emitted from the ocean and may represent up to 90% of the sea-to-air biogenic sulfur flux. It has been hypothesized that cloud formation caused by condensation nuclei associated with products of DMS oxidation can directly counteract warming effects of anthropogenically produced CO2. Despite the global importance of DMS and related sulfonium compounds, and the significant role of aquatic systems in DMS production (particularly in south polar regions), the sources and sinks of DMS and associated sulfonium compounds remain equivocal. Our proposed multi-investigator field and laboratory research will examine the biogeochemistry of water column and sedimentary DMS/DMSP (dimethylsulfoniopropionate), and the role of associated compounds (e.g. dimethylsulfoxide, dimethylated polysulfides) in Lake Bonney. Lake Bonney is a relatively simple (no turbulence, no grazers and little atmospheric exchange) aquatic system and therefore provides a highly tractable environment for investigating microbially mediated cycling of biogenic sulfur. Preliminary data suggest that maximum levels of DMS precursors occur in the deep-chlorophyll layer of the lake, a zone dominated by cryptophyte algae. In addition, DMS concentrations in the aphotic waters of Lake Bonney are among the highest recorded in a natural aquatic system. These observations indicate that precursors produced by trophogenic zone phytoplankton sink to the aphotic waters and sediments where they are microbially decomposed to DMS and other sulfur compounds. The proposed research will define the sources and sinks of DMS and associated compounds and relate them to overall ecosystem function. A model of biogeochemical transformations of organo-sulfur compounds in Lake Bonney will be developed.