典型土壤团聚体中氯素种态及其再分配机制的原位研究

Increasingly serious soil pollution has attracted wild attention due to the direct/indirect threats to the human health and it is a great obstacle for the sustainable economic development in China. The adsorption mechanism between soil aggregates and pollutants is of a multi-disciplinary hot topic. Due to the limitations of the analytical tools, the research progress on the chlorine speciation is very limited.There is no report about the characteristics of chlorine speciation in the soil aggregates yet. An in situ procedure are developed for the first time by X-ray absorption near-edge spectroscopy(XAFS) together with instrument of neutron activation analysis (INAA) as well as other analytical technologies to quantify the inorganic chloride (Clinorg) and organochlorine(Clorg), as well as the alphatic Clorg and aromatic Clorg in typical soil aggregates in China. The redistribution mechanisms and transformation effected fators in the interfaces are to be investigated in terms of the composition of aggregates. The study will provide scientific evidence for the control and risk assessment of organochlorine in the comprehensive contaminated soil with important academic and social significance. In addition, this project will broaden the application of advanced nuclear analytical techniques in the interdisciplinary of environmental science.

日益严重的土壤污染因直接或间接地威胁人类健康而备受关注，是我国经济可持续性发展的极大障碍。污染物与土壤团聚体的结合机制是环境科学等多个学科的研究热点。有机氯化物是土壤中典型的有机污染物之一，但由于分析手段的局限性，目前鲜有关于团聚体中氯素（特别是有机氯化物）种态特征及其环境行为的研究报道。本项目拟以同步辐射先进光源为研究平台，以我国典型土壤团聚体为研究对象，充分发挥X射线近边吸收精细结构谱（XAFS）和中子活化分析（INAA）的技术优势，对土壤团聚体中无机氯、芳香族有机氯和脂肪族有机氯的组成特征进行原位解析，并结合其他表征方法揭示团聚体组成差异对氯素种态再分配的影响机制，从分子层面探讨其界面转化机理。本研究将为我国复合污染土壤中有机氯污染物的防控及生态风险评价提供科学依据，具有重要的学术价值和社会意义。另外，本项目将拓宽先进核分析技术在环境科学领域中的应用。

本项目以同步辐射先进光源为研究平台，以我国典型土壤团聚体为研究对象，充分发挥X射线近边吸收精细结构谱（XAFS）技术优势，对土壤团聚体中无机氯、芳香族有机氯和脂肪族有机氯的组成特征进行原位解析，并结合其他表征方法揭示团聚体组成差异对氯素种态再分配的影响机制。我国仅栗钙土及砖红壤中氯素含量稍高于我国氯素均值，大多数土壤均为缺氯土壤；有机氯为土壤中氯元素的主要种态，其浓度为无机氯浓度的1~3倍，其中脂肪氯为有机氯的主要存在形态。无机氯和有机氯都更易于富集在微团聚体中，其再分配受团聚体组成的制约与团聚体有机碳及重金属分布具有显著相关性。本研究将为我国复合污染土壤中有机氯污染物的防控及生态风险评价提供科学依据，具有重要的学术价值和社会意义。