由于放射性核素36Cl与稳定核素氯在土壤中的迁移行为几乎一致，因此随着对核工业等过程产生的36Cl危险评估的关注，稳定核素氯的环境行为成为了近年的研究热点。目前尚缺乏城市土壤中氯素赋存种态特征及其非生物转化机制的研究。本项目拟发挥同步辐射分析技术的独特优越性，选择北京城区不同季节不同功能区的浅表层土壤为研究对象，对稳定氯素的赋存种态进行原位解析；同时，结合其他表征技术研究土壤中不同氯种态的吸附行为。本项目将从分子水平上阐明典型大城市土壤中氯种态特征及其非生物转化响应机制，有助于建立更准确的污染物迁移预测模型，并更加合理的评估36Cl和其他污染物的环境风险。本项目将为我国城市土壤中典型核素的污染防治提供科学依据，同时拓宽同步辐射分析技术在交叉学科中的应用，具有重要的学术价值和社会意义。

Typical radionuclide 36Cl was shown to have the same behaviour as stable nuclide Chlorine in soils. Therefore, the environmental behavior of stable chlorine species has become a hot issue with the increasing focus on the risk assessment of 36Cl radionuclide formed with the process of nuclear industry in recent years. There is still a lack of in-situ study on the typical chlorine species and their abiotic transformation mechanism in metropolis urban soils. In this study, the behavior of chlorine species in urban soils in Beijing will be charactered by in situ synchrotron radiation-based techniques. Toghter with other anlalytial chemistry methods, the factors effecting chlorine species in those two different typies of soil will be intensive studied. The mechanism will be revealed on molecular scale as well. This project will provide scientific evidences for the better risk assessment of 36Cl radionuclide and attribute to the more accurate prediction model for pollutants migration in typcial city soils in China. This project will broaden the application of synchrotron radiation analytical techniques in the interdisciplinary of environmental science and lay a foundation for the control of composite pollution in urban soil with important academic and social significance.