Project types：Natural Science Foundation of China Director：Jianfeng Tang From 2014.01 to 2016.12 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.