ISOTOPIC STUDIES ON COS AND DMS GENERATION AND THEIR BEHAVIOR IN THE ENVIRONMENTAL CYCLE OF SULFUR

点击翻译按钮获取中文摘要

The purpose of this research is to investigate the behavior of dimethyl sulfide (DMS) and carbonyl sulfide (COS) in the environment by means of sulfur isotopic measurement. Investigaters have already determined sulfur isotopic compositions of coals and petroleum those combustion gas acidify the environment. Now DMS and COS which have a natural origin are considered seriously as acidifing the environment.Summary of this research results is composed of 2 parts : 1) Investigaters set forth a hypothesis that a red tide acidifies the environment, depending on some reports that 10^4 fold of DMS compared as usual is released at a period of red tide. The biosensor for forcasting a red tide was develored. Cultivation of algae which generate DMS at a period of red tide was examined. As a final goal is to determine the sulfur isotopic composition of DMS releasedfrom the sea, the collecting system of DMS from the surface air of the ocean was investigated. 2) COS generated from KSCN by Tiobacillus thioparus in the laboratory was collected and its sulfur isotopic composition was determined. An isotopic fractionation was observed by the biological process. The next step is to collect COS released from the soil and determine the sulfur isotopic composition. Investigaters are attempting to discriminate the sulfur source in the environmental samples such as air, rain water, snow, river water, plants based on the data of sulfur isotopic composition from the sea water sulfate, volcanic gas, DMS, COS and fossil fuels.