华南地区酸沉降的硫同位素组成及其环境意义

Sulfur isotopic composition of acid deposition in South China Regions and its environmental significance.

为探讨华南珠江三角洲和湘桂走廊及其周边地区的酸沉降硫源,分别对大气降水、大气SO2、气溶胶和工业用煤、重油及其燃烧产物进行了硫同位素组成测定.研究结果表明,珠江三角洲和湘桂走廊地区的大气降水硫同位素组成有明显的差异,其大气降水δ34S值的变化范围分别为1.9‰~10.3‰和-4.8‰^-0.1‰.湘桂走廊地区大气降水明显的富集轻硫同位素(32S),而珠江三角洲地区则富集重硫同位素(34S).在煤、重油燃烧过程中硫同位素分馏效应研究基础上,将该地区酸雨硫源区分为4种类型,即人为成因硫、天然生物硫、海雾硫和远距离传输硫.在定量计算不同硫源对酸雨贡献的基础上.提出人为成因硫是珠江三角洲和湘桂走廊地区最强的污染硫源,而生物硫在夏季贡献突出,其贡献率分别为47%和52%.传输硫在冬季贡献率可达49%.上述结果,对研究治理华南地区的酸雨具有重要意义.

In order to study the source of acid deposition in Pearl River Delta, Xiang-Gui Corridor and surrounding areas in South China, the sulfur isotopic composition of precipitation, atmospheric SO2, aerosol and industrial coal, heavy oil and their burning products were measured. Results show that the sulfur isotopic compositions of precipitation are distinguished obviously between regions of Pearl River Delta and Xiang-Gui Corridor. The values of d 34S of precipitation in these two regions vary in the range from 1.9‰ to 10.3‰ and -4.8‰ to -0.1‰, respectively. It is indicated that the sulfur isotopic composition of precipitation of Xiang-Gui Corridor is enriched in 32S, however, which of the Pearl River Delta is enriched in 34S. Based on study of fractionation effect of sulfur isotope of coal- and heavy oil-burning process, four sulfur origins of acid rain in these regions are tractionized: anthropogenic sulfur, biogenic sulfur, sea spray sulfur and far-transport sulfur. Based on the quantitative calculation of the source contribution, anthropogenic sulfur is major sulfur pollution source of precipitation in Peatl River Delta and Xiang Gui Corridor areas and biogenic sulfur is obvious in summer with their contribution rate of 47% and 52% respectively. In winter the rate of transport sulfur could be up to 49%. These results have important significance for research to harness acid rain the South China.