碳/氢稳定同位素用于塑化剂和溴阻燃剂环境降解机理研究

Taken offshore sediments and urban surface soil as typical environmental media, the response mechanism between changes of carbon and hydrogen stable isotope signature and environmental degradation of phthalate and brominated flame retardants will be explored in the present program based on stable isotopic analysis and kinetic isotope effect (KIE). Also, environmental degradation mechanism of the target pollutants will be studied. At the same time, carbon and hydrogen stable isotope analysis was adopted to eliminate the impact of environmental factors on the isotopic fractionation of given element by analyzing the fractionation of different isotope for achievement of better explanation of environmental degradation of these pollutants. The research idea is to draw a decaycurve base on measurements and then obtain information of isotope fractionation with compound-specific isotope analysis. Finally, environmental degradation of target pollutants will be revealed via isotope fractionation, KIE, AKIE, and ratio of enrichment factors for different isotopes. Based on that, a new method will be developed to examine the evidence for the predominant degradation pathway and estimates of the extent of various degradations with the multidimensional stable isotope analysis.

选取近海沉积物及表层土壤为典型环境介质，以塑化剂和溴系阻燃剂为目标污染物，以稳定同位素分析为基础，分析目标物环境降解过程与C和H同位素变化之间的响应关系，探索塑化剂和溴系阻燃剂环境降解（生物和光降解）机理。同时，通过对C和H同位素分馏的相关性分析，削减环境因素对有机污染物降解过程同位素分馏行为的影响，以期获得对降解机制更为准确、客观的认识。研究基本思路：采用色谱质谱联用技术，测定目标物质在沉积物和土壤中浓度变化，绘制目标污染物降解曲线；获得降解趋势信息，拟合与修正污染物降解动力学方程；根据目标物降解过程C和H同位素分馏信息（动力学同位素效应、表观动力学同位素效应以及不同元素富集因子之比），结合分子结构，揭示降解机理。项目核心目标：尝试建立多维稳定同位素分析用于有机污染物环境降解机理研究的新方法。

邻苯二甲酸酯(PAEs)作为增塑剂和添加剂被广泛使用，其在自然界的直接或间接释放产生了很高的生态风险。其降解机理和降解产物的研究对于生态/环境风险评估和污染物地球化学循环分析非常关键。本研究调查了两种邻苯二甲酸酯(PAEs)，邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二正辛酯(DOP)于模拟太阳光下在水相或有机相(正己烷(HEX)和二氯甲烷(DCM))中的直接光解反应。 光解动力学按半衰期排序为:DOP在DCM中(3.77小时)> DMP在DCM中(9.62小时)> DOP在H2O中(3.99天)> DMP在H2O中(19.2天)> DOP在HEX中(21.0天)> DMP在HEX中(> 30天)。 DMP在DCM光解过程中出现了一种毒性较强、较难降解的中间体，而DOP在有机溶剂中光化学转化则降低了对人体健康的危害。本研究采用化合物特异性稳定同位素分析(CSIA)和中间产物分析相结合的方法探讨了反应机理。PAEs在H2O中、DMP在DCM中、DOP在DCM中、DOP在HEX中光解起作用的降解机理分别为 C-O键断裂、氯自由基在芳香环上的吸附、氯自由基在芳香环和侧链上的竞争反应和单重态氧介导途径。 此外，不同的碳同位素分馏模式可以进行涉及溶剂的区分。