氯代阻燃剂得克隆及其相关化合物在珠三角地区主要介质中的环境行为和演变态势

As a flame retardant substitute of the persistent organic pollutant (POPs) Mirex, Dechlorane plus (DP) has been produced and used for almost fifty years. However, its environmental pollution did not cause any concern until 2006 when it was firstly identified and reported in the environment. Due to its persistency, long-range transport and bioaccumulativity suggested by now available environmental measurements, DP may be considered as candidate for Annex D evaluation under the United Nations Stockholm Convention on POPs. The Young Scholar Project (No. 40903043) is the first project on environmental DP in China supported by National Natural Science Funds. In this project, the concentration levels, occurrence modes, spatial distribution and main sources of DP have been systematically investigated in typical e-waste dismantling areas and industrial areas of Pearl River Delta (PRD). Some dechlorination products of DP, DP-1Cl and DP-2Cl, were found in the samples. Two relevant research papers were published on Environment Pollution, and one conference paper for the Dioxin 2010 Symposium was published on Organohalogen Compounds. Recently, with the deepening study on DP worldwide, DP’s related compounds, e.g. by-products, degradation products and structural analogs, have also been paid increasing attention to. Some of them have showed higher bioaccumulativity than DP. But their source, environmental behavior and interrelation with DP are still unclear. In this continued program, further studies on DP and related compounds in main environmental media of PRD are planed to be carried out based on the previous project. Levels, distribution, transformation, sources and mutual relations of these compounds will be systematically studied with the aim to reveal their pollution situation, environmental geo-chemical behavior, trend and fate in this area, and also to provide scientific basis for the risk assessment and rational use of these pollutants.

得克隆（DP）作为POPs污染物Mirex的替代品已使用近五十年，但其环境污染自2006年被首次报道后才引起关注，已有数据表明其具有持久性、长距离迁移性和生物富集性，可能会被列入POPs公约附件D考察清单。作为我国环境中DP首个立项的国家基金，申请人主持的青年项目系统研究了珠三角典型电子垃圾拆解区和工业区土壤中DP的污染特征和来源，并在样品中识别出其脱氯产物（DP-1Cl/2Cl），在Environ. Pollut.上发表相关论文2篇，国际会议论文1篇。随着研究深入，DP相关的副产物、降解产物和结构类似物近期也受到关注，部分化合物表现出比DP更强的生物富集性，但其来源、环境行为及与DP的关联尚不清楚。本项目拟在青年基金基础上，研究DP及其相关化合物在珠三角地区主要环境介质中的污染分配、迁移转化、来源及相互关系，揭示该区域此类污染物的现状、环境行为和演变态势，为其风险评估和合理使用提供依据。

近年来，得克隆（DP）及其相关化合物被发现在全球范围内广泛存在，且表现出持久性、长距离迁移性和生物富集性等POPs特性，由此受到强烈关注，但目前对其来源、环境行为和演变态势尚不清楚。本项目在前期对DP的研究基础上，建立了多种DP类化合物的高灵敏度高选择性联合分析方法，并系统研究了DP及其相关化合物在珠三角地区不同功能区大气、水体、沉积物和土壤等主要环境介质中的污染水平、空间分布特征、介质分配规律、迁移转化行为、污染来源、时间演变态势、暴露剂量计算模型和风险控制因素。研究结果表明：① DP类化合物在珠三角地区各类环境介质中被广泛检出，电子垃圾拆解区污染水平最高，其次是工业区和城市地区，背景区最低，与世界其它地区相比处于中等污染水平；② DPs类化合物主要存在于大气颗粒相和沉积物中，以DPs、Mirex和Dec-602为主，可随大气和水体活动向周边地区迁移并产生影响，但迁移距离有限，介质有机碳含量是影响其迁移过程的重要因素；③ DPs在环境中存在异构体转化和脱氯降解行为，但环境中DPs的脱氯产物（Cl10DP与Cl11DP）仅部分来自于DPs在环境中的脱氯降解，部分则与DPs具有相同的排放源；④ 电子垃圾拆解活动、工业/城市活动是珠三角环境中DPs类化合物的主要来源，其中水环境中大部分DPs化合物主要来源于工业排放，少量化合物主要来自于生活污水排放；⑤ 近十年来，电子垃圾拆解区环境中的DPs浓度呈现显著下降趋势，这与进口电子洋垃圾和粗放式电子垃圾拆解活动受到管制有关，但珠三角工业区、城市和背景区各类环境介质中的DPs浓度均呈现不同程度的明显的上升趋势，这说明DPs近年来作为溴代阻燃剂的替代品在珠三角地区的使用量有所增加；⑥ Monte Carlo模拟可有效降低暴露剂量计算和风险评估的不确定性，并可确定出暴露风险的关键控制因素。研究结果可为珠三角地区DPs类化合物的风险评估、污染控制和合理使用提供了翔实的数据参考和科学依据。