Isotope Chemistry for the Studies on COS・DMS Generating Mechanism and Their Behavior in Environment

同位素化学研究 COS・DMS 生成机制及其在环境中的行为

基本信息

批准号：
12680531
负责人：
ARIKAWA Yoshiko
金额：
$ 2.3万
依托单位：
Japan Women's University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Carbonyl sulfide(COS) is produced by microbes such as Thiobacilius thioparus under the presence of thiocyanates in soil. On the other hand dimethly sulfide(DMS) is produced in the sea by algae and the sulfur in the compound comes from the sea water sulfate. In both cases microbes use inorganic sulfur to generate COS and DMS. Why they don't use organic sulfur? To elucidate this problem the experimental generation of COS and DMS were examined by adding organic sulfur compounds in the medium. In the case of cultivating Thiobacillus thioparus by adding aryl isothianate as organic sulfur, microbes did not breed. For DMS it took long times to find algae which breed effectively in the laboratory. Cricosphaera roscoffensis NIES 8 and Alexandrium catenella NIES 677 were recognized to generate DMS in the sea water medium experimentally.The predominant means to identify the origin of sulfur in the compounds is isotopic (^<32>S/^<34>S) measurement. For the isotopic measurement the collection method of COS and DMS were investigated. COS was introduced in ethane, added by Zn(CH_3COO)_2 to form ZnS which is converted to Ag_2S. DMS was adsorbed on silica gel with titanium oxide photo catalyst which is then irradiated by ultraviolet ray(350〜380nm). The formed SO_2 is introduced to hydrogen peroxide solution to be oxidized to SO_4^<-2> which is finally converted to Ag_2S. The sulfur isotopic measurement is carried out for SO_2 formed from Ag_2S described above. For COS isotopic fractionation by microbe metabolism was observed. δ^<34>S value (6.1‰) of thiocyanate sulfur as a standing material went to be lower as 3.8‰. This result is expected to be useful for the discussion of behavior of environmental sulfur.

硫羰（COS）是由硫杆菌等微生物在土壤中的硫氰酸盐存在下产生的，而二甲硫醚（DMS）是在海洋中由藻类产生的，化合物中的硫来自海水硫酸盐。在这两种情况下，微生物都使用无机硫来生成 COS 和 DMS，为什么它们不使用有机硫？为了阐明这个问题，通过在培养基中添加有机硫化合物来检查COS和DMS的实验产生。在通过添加异硫酸芳基酯作为有机硫来培养硫杆菌的情况下，微生物没有在DMS中繁殖很长时间才能发现藻类。 Cricosphaera roscoffensis NIES 8 和 Alexandrium catenella NIES 677 在实验室中有效繁殖。实验性地在海水介质中生成DMS。鉴定化合物中硫的来源的主要手段是同位素(^ 32 S/^ 34 S)测量。对于同位素测量，COS和DMS的收集方法如下。将COS引入乙烷中，加入Zn(CH_3COO)_2形成ZnS，然后将其转化为Ag_2S，并用硅胶吸附。氧化钛光催化剂，然后用紫外线(350～380nm)照射，将形成的SO_2通入过氧化氢溶液中，氧化成SO_4^-2，最后转化为Ag_2S，进行硫同位素测定。对于由上述 Ag_2S 形成的 SO_2，观察到微生物代谢引起的 COS 同位素分馏。作为常备材料的硫氰酸盐硫的δ^ 34 S值(6.1‰)降低至3.8‰，该结果预计对于环境硫的行为的讨论是有用的。