| 酸沉降环境化学与硫同位素示踪研究──以浙江中部地区为例 | |
| Alternative Title | Environmental Chemistry of Acid Deposition and Sources Attribution Using Sulfur Isotopic Compositions──A Case Study in the Central Region of Zhejiang Province |
| 张苗云 | |
| 2006-08-30 | |
| Degree Grantor | 中国科学院地球化学研究所 |
| Place of Conferral | 地球化学研究所 |
| Degree Name | 博士 |
| Keyword | 环境化学 酸沉降 大气降水 硫同位素 统计分析 富集系数 均相氧化 多相氧化 |
| Abstract | 研究区域降水样品pH值的分布范围为3.64-7.20，pH年均值为4.45。SO4、NO3、NH4、Ca、H是降水中主要的阴、阳离子。降水中SO4对降水酸度的贡献逐渐降低，而NO3的贡献则显著增加。SO4、NH4、Ca、H、NO3的沉降通量相对较大，其它离子则相对较小，同时降水离子成分沉降通量的季节变化非常明显。SO4和NO3、Ca和Mg以及Na和Cl表现出较好的相关关系，另外Ca和SO4、Mg和SO4以及Mg和NO3等酸、碱性离子之间也存在较好的相关性，但H与其它离子间并没有表现出明显的相关关系。降水中SO4、NH4、NO3和F主要来自人为活动的影响，Ca、k和Mg主要来自土壤、沙尘等地壳来源，Na、Cl属于典型的海盐性成分。 浙江中部地区大气降水硫同位素δ34S值的变化范围为+0.53‰－+14.23‰，平均值+5.04‰，区域内各地大气降水硫同位素组成基本一致。大气SO2的δ34S值变化范围在+0.95‰－+7.50‰之间，年均值为+4.73‰，气溶胶δ34S值变化范围则在+6.39‰－+9.83‰之间，年均值为+8.09‰。降水和大气SO2的δ34S值存在冬季高夏季低的季节性变化特征，同位素平衡分馏引起的温度效应和夏季生物成因硫的大量释放是造成季节性变化的主要控制因素。降水中人为来源硫的相对贡献约为53%－91%，年平均为73%，生物成因硫的相对贡献约为8%－44%，年平均为26%。远距离传输硫是研究区域降水中另一个非常重要的硫源，其相对贡献约为27%－44%。大气SO2氧化反应中多相氧化处于相对重要的地位，均相氧化在氧化反应机制中也有其不可低估的作用。研究区域大气环境的相对湿度对大气SO2的氧化机制有着重要的影响。 |
| Other Abstract | The rainwater in the studied areas was typically acidic with a volume-weighted mean pH of 4.54, ranged from 3.64 to 6.76. SO4 and NO3 were the main anions, while NH4,Ca and Mg were the main cations. Even though SO4 was the dominant anion in precipitation, the SO4 contribution to precipitation acidity was reduced obviously and its sulfur-pollution character was weaken, while that of NO3 was markedly enhanced. SO4, NH4, Ca, H, NO3 had relative high deposition flux among all the ions, the deposition loading of the other ions were low in the precipitation. Seasonal variations of wet depositions are extremely apparent for all the components. SO4 and NO3, Ca and Mg as well as Na and Cl showed obvious correlations in this study. Other relatively good correlations were observed between the acidic and alkaline ions such as Ca and SO4, Mg and SO4, Mg and NO3. However, H showed no significant correlations with other ionic species. The results suggested that SO4, NH4, NO3, F were mostly attributed to the anthropogenic activities, Ca, Mg and K came mainly from the terrestrial source as well as Na and Cl from the marine source. The values of δ34S of precipitation vary in the range from +0.53‰ to +14.23‰, with a meanδ34S values of +5.04‰. Sulfur isotopic composition of precipitation is basically identical in the spatial distribution. The values of δ34S of atmospheric sulfur dioxide vary in the range from +0.95‰ to +7.50‰, with annual meanδ34S values of +4.73‰. The values of δ34S of sulfate aerosols vary in the range from +6.39‰ to +9.83‰, with annual meanδ34S values of +8.09‰. The results showed striking seasonality between summer and winterδ34S values of precipitation and atmospheric sulfur dioxide in the central region of Zhejiang province with the summer samples being generally depleted in 34S compared with winter. The seasonal pattern ofδ34S values of precipitation and atmospheric sulfur dioxide may be explained by the temperature dependence of the isotope equilibrium fractionation associated with SO2 oxidation reaction during sulfate formation in the atmosphere. A greater relative contribution of biogenic sulfur during the summer also may have contributed to the lowerδ34S value in the summer. Anthropogenic sulfur is major sulfur pollution source of precipitation in the studied areas. The relative contributions of anthropogenic sulfur of different seasons in precipitation range from 53% to 91%, with an annual mean of 73%. The relative contributions of biogenic sulfur of different seasons in precipitation range from 8% to 44%, with an annual mean of 26%. Long distance transport sulfur is another important sulfur source in precipitation and its relative contributions vary in the range from 27% to 44%. The results suggested that heterogeneous oxidation of sulfur dioxide was dominant in the atmosphere of the studied areas. On the other hand, the obtained data also showed that homogeneous oxidation also played an important role in the mechanisms of oxidation reaction. Furthermore, the results also suggested that relative humidity in the atmosphere has an important influence on the oxidation mechanisms of sulfur dioxide in the studied areas. |
| Pages | 131 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.gyig.ac.cn/handle/352002/3140 |
| Collection | 研究生_研究生_学位论文 |
| Recommended Citation GB/T 7714 | 张苗云. 酸沉降环境化学与硫同位素示踪研究──以浙江中部地区为例[D]. 地球化学研究所. 中国科学院地球化学研究所,2006. |
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