短链氯化石蜡在水生和陆生食物链中的差异性富集及其机理研究

Short chain chlorinated paraffins (SCCPs) are a complicated group of chlorinated organic pollutants that have recently raised attention in many studies. Species-specific bioaccumulation of SCCPs was observed in aquatic and terrestrial organisms. However, it is still unclear about the specific process and mechanism of SCCPs accumulated in aquatic and terrestrial food chains. In the present study, exposure pathway (dietary and aqueous), absorption, excretion and biotransformation of SCCPs in aquatic (fish) and terrestrial (bird) species will be investigated in laboratory in vivo exposure experiments and in vitro metabolism experiments to explore the influence of these biological processes on the bioaccumulation of SCCPs. Furthermore, in situ accumulation of SCCPs in aquatic and terrestrial food chains will be examined in an area without point source pollution, in comparison with our laboratory studies. Finally, we attempt to understand the bioaccumulation processes of SCCPs in aquatic and terrestrial food chains, and to elucidate the mechanism of species-specific bioaccumulation of SCCPs. The project will improve our understanding on the environmental behavior and fate of SCCPs in the ecosystem, and provide guidelines for the evaluation of SCCPs ecological and health risks and the fulfillment of the Stockholm convention on persistent organic pollutants.

短链氯化石蜡（short-chain chlorinated paraffins，SCCPs）是近年来备受关注的一类组成复杂的氯代有机污染物。前期研究发现SCCPs在水生和陆生生物中表现出差异性富集现象，但是SCCPs在不同食物链中的差异性富集规律及其机理尚不清楚。本研究拟以水生鱼类和陆生鸟类为对象，通过体内暴露（饮食和水体暴露）实验和体外代谢实验相结合，了解生物的暴露途径、吸收、排泄和代谢转化差异及对SCCPs生物富集特征的影响。在暴露实验结果的基础上，参照非点源污染区域野外原位水生和陆生食物链的SCCPs污染模式和生物富集结果，揭示SCCPs在水生和陆生食物链上的生物富集和迁移的规律及其机制。本项目的完成将增进我们对SCCPs的环境行为和归趋的认识，为正确评价SCCPs的生态和健康风险以及合理履行斯德哥尔摩持久性有机污染公约提供理论依据。

短链氯化石蜡（short-chain chlorinated paraffins，SCCPs）是近年来备受关注的一类复杂的新兴持久性有机污染物。了解氯化石蜡的生物富集特征和机理是弄清其环境归宿和毒性以及科学评价其生态风险的重要环节。本项目以水生鱼类和陆生鸟类的代表性物种研究了SCCPs在水生和陆生食物链上的生物富集规律及其机制。结果显示，鱼类的SCCPs生物积累参数主要受控于logKOW的变化，与陆生鸟类SCCPs积累系数受控于logKOA的变化差异明显。鱼类与水体相关的生物积累参数BAF值随着logKOW的增加先增加，至logKOW到一定值后略有降低。当生物从水中富集SCCPs时，高logKOW的单体更倾向于富集到生物体中；但是当logKOW增大到一定值时，受到化合物的生物可利用性降低、清除速率提高以及生物体内代谢速率也提高等多重因素的影响导致生物积累潜力不在增加甚至下降的现象。受食源影响的鱼类的生物放大系数BMF值则随着logKOW增大而降低。鸡从食源中富集SCCPs的能力（AR）随着logKOA的增加而降低。高KOW的SCCPs单体一般具有高的KOA。具有高logKOW和logKOA的SCCPs通常是碳链较长氯原子数目较多的分子量和分子体积较大、分子结构更为复杂SCCPs同系物组。这些SCCPs通过食源被摄入后可能由于其大的分子体积带来的空间位阻导致不利于透过细胞膜被消化吸收。与之相比，低logKOW的单体在消化吸收过程中易于从介质中释放和被吸收造成在生物体较高的积累。与水体暴露来源为主的鱼类相比，同时受到水体和食物暴露的鱼类体中低碳链的SCCPs比例出现上升；但是与陆生鸟类鸡相比，水生鱼类更容易富集高氯代的SCCPs。本项目的完成增进了我们对SCCPs的环境行为及归宿的了解，为合理地履行POPs公约提供了科学的依据。