六溴环十二烷在沉积物-水界面的交换过程及其机理研究

Hexabromocyclododecanes (HBCDs) are emerging organic pollutants which have been of increasing global environmental concern due to its persistent,bioaccumulation,toxicity and long distance migration characteristics,it is a serious threat to human health and ecological security. Although many studies have investigated the occurrence and distribution of HBCDs in sediment and water environments, only a few studies have examined the environmental fate and freely dissolved concentrations of HBCDs in aquatic environments, and little is known about the exchange process and mechanism of HBCDs at sediment-water interface.In this project,the passive sampler triolein embedded acetate membrane (TECAM) will be used to measure the freely dissolved HBCDs in pore water and overlying water at sediment-water interface, this will allow for exchange fluxes to be calculated in addition to the kinetic process of adsorption or desorption of HBCDs on the sediment solid phase; the effects of different natural organic matter on the freely dissolved concentration of HBCDs will also be investigated,the natural organic matter are of different source and composition in sediment or water,and then the key factors influencing the freely dissolved HBCDs at the sediment-water interface are only understood in a general sense.The findings from this proposal will provide important detail which is required to improve ecological risk assessment in aquatic environments.

六溴环十二烷是一类具有持久性、生物累积效应、生物毒性以及远距离迁移性特点的新型有机污染物，严重威胁生态安全和人类健康。以往关于环境中HBCDs的研究主要集中在污染水平、分布特征和污染来源等方面，而关于沉积物-水环境中的环境行为和自由溶解态方面的研究非常薄弱，HBCDs在沉积物-水界面的交换过程和机理尚不清楚。本项目在利用课题组前期研发的三油酸酯-醋酸纤维素膜（TECAM）生物模拟采样技术建立原位监测沉积物-水中HBCDs方法的基础上，采用TECAM技术现场同步测量沉积物-水界面附近上层水和沉积物间隙水中目标物的浓度分布，估算沉积物-水界面的交换通量强度与方向，示踪沉积物富集和释放HBCDs的动力学过程；同时深入剖析沉积相和水相中不同来源和组成有机质对HBCDs自由溶解态浓度水平的影响程度及其机理，揭示影响HBCDs自由溶解态浓度水平的关键有机质组成，进而明确HBCDs的水环境行为及其机理。

六溴环十二烷（简称HBCDs）作为一类全球关注的新型污染物，具有持久性、生物累积效应、以及远距离迁移特点的新型有机污染物。有关沉积物-水环境中HBCDs的环境行为和生物有效性的研究相当欠缺。本项目在采用TECAM被动采样技术研究了TECAM对HBCD的富集效果，并建立了沉积物孔隙水中HBCDs的测定方法体系，结果表明，α-HBCD, β-HBCD and γ-HBCD在TECAM上的富集平衡分配系数log KTECAM 分别为4.69，4.77和4.63。进一步研究了HBCDs在沉积物-水多介质的分配规律表明，在沉积物-孔隙水中体系中，超过99.9%的HBCDs与沉积物结合，而在水相中，与DOM结合的HBCDs也超过99.0%，其结合程度与DOC含量和性质密切相关，导致其自由溶解态浓度很低，在所测试的3种沉积物孔隙水中，其DOC-平衡分配系数log KDOC 值在5.77-6.23之间，表明很强的与DOC结合的能力。本项目还研究了不同浓度悬浮颗粒物对水相HBCDs浓度的影响机制，并探讨了DOM对水相中HBCDs自由溶解态浓度的影响程度，结果表明DOM的含量与性质直接影响到HBCDs自由溶解态的浓度，并应用PRCs（Permeability/performance reference compounds）方法在野外原位应用。