Marine Biogeochemistry of Dissolved DMSP and its Sulfur Containing Degradation Products

这项为期三年的研究将增加我们对溶解DMSP在表层海水中还原性硫的生物地球化学中所起作用的基本认识。该项目的具体目的是：1)检验常规过滤技术测得的溶解DMSP池是否真正溶解；2)使用14C和35S DMSP测量天然微生物组合对溶解DMSP的吸收动力学，并确定DMSP的原位周转率(d)；3)测定DMSP降解过程中产生的硫产物，确定不同水体中裂解酶（DMS形成）和去甲基化（甲硫醇形成）途径的分支比例变化；4)确定好氧海水中甲硫醇生产的机理，最后确定MeSH在海水中的损失动力学及其影响因素。这项工作将主要利用墨西哥北部海湾的沿海和大陆架水样本进行，但计划进行两次海洋学巡航，以从温暖的少营养和凉爽的中营养海水中提供补充信息。由此得出的数据将大大提高我们对DMSP在海洋中是如何加工的认识，以及它是如何通过产生DMS和甲硫醇等重要的还原硫化合物来影响地表水的化学性质的。

9530378 Kiene This three year study will increase our fundamental understanding of the role played by dissolved DMSP in the biogeochemistry of reduced sulfur in surface seawater. The specific objectives of the project are 1) to test whether the dissolved DMSP pool measured by conventional filtration techniques is truly dissolved; 2) to measure the kinetics of uptake for dissolved DMSP by natural microbial assemblages using 14C and 35S DMSP and to determine in situ turnover rates for DMSP (d); 3) to measure the sulfur products formed during DMSP degradation and to determine how the branching ratio between the lyase (DMS forming) and demethylation (methanethiol forming) pathways vary in different waters; 4) to determine mechanisms of methanethiol production in aerobic seawater and finally, to determine the loss kinetics of MeSH in seawater and the factors which affect these. The work will be carried out using primarily coastal and shelf water samples from the Northern Gulf of Mexico, but 2 oceanographic cruises are planned to provide complementary information from warm oligotrophic and cool mesotrophic ocean waters. The resulting data should greatly advance our knowledge of how DMSP is processed in the sea and how it impacts the chemistry of surface waters through production of important reduced sulfur compounds like DMS and methanethiol.