Studies On Biogeochemistry Of DMS And DMSP In The Microlayer And Subsurface Water

Dimethylsulfide (DMS) is one of the major biogenic sources of sulfur to the atmosphere. The atmospheric oxidation products of DMS not only contribute to acid precipitation, but may also influence climate due to the formation of cloud condensation nuclei. DMSP (dimethylsulfoniopropionate), which is the main precursor of DMS, has emerged as a fascinating compound in the microbial ecology and biogeochemistry of the surface ocean. Taking advantage of deep research effort made for a long period, the DMS/DMSP story offers a unique opportunity to link atmospheric chemistry and climate to the ecology and evolution of marine community.The distribution of DMS and DMSP in China seas, i.e. the South China Sea (representating the open ocean), the Yellow Sea (representating the shelf sea) and Qingdao coastal waters (including Jiaozhou Bay, representating the coastal water) and factors influencing them were systematically studied in this dissertation. Another objective of this study was to examine the distribution and variability of DMS and DMSP in the sea-surface microlayer by sampling the water with a screen sampler. Some important conclusions were drawn as follows:1 The gas-stripping chromatographic methods have been developed in our lab for the determination of trace quantities of DMS in seawater. The trapped gases were desorbed and analyzed using a Shimadzu GC-14B gas chromatograph equipped with a flame photometric detector after separation using a 2-m glass column packed with 10% DEGS on Chromosorb W-AW-DMCS. The detection limits were 0.15 ng S (0.0047 nM), and the precision was better than 8%.2 Distributions of DMS and DMSP were determined during in situ surveys in the South China Sea and the Yellow Sea in March and May 2005. The cruises were undertaken as part...