珠江口难降解有机物高污染区的形成和影响研究

Two heavily polluted sediments, which potentially pose adverse biological effects, were found in the Pearl River Delta from the analysis of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, and polychlorinated biphenyls (PCBs) in sediments from Guangzhou channel at Pearl river and Macao harbor. The sources and transport pathway of PAHs to Macao coastal sediments have been investigated using PAH compositional indices and principal component analysis (PCA). The results shown that the major sources of PAHs to the sediments are the petroleum-derived PAHs (alkyl-PAHs and sulfur/oxygen-PAHs) and combustion-derived PAHs (high molecular weight PAHs). The high-molecular-weight parent PAHs (with more than 5 ring) in sediments of Macao coastal waters were inputted predominantly by the direct and indirect deposition of atmospheric particles. The low-molecular-weight parent PAHs were transported to sediments probable by river runoff or/and directed discharge, and air-water exchange. The distribution profiles of POPs in water column from Guangzhou channel and Macao harbor suggested that the contaminated sediments in the Guangzhou Channel have became a secondary source of POPs and may release some POPs (such as DDTs and PAHs) to waters by sediment resuspension during high flow season, howener, the Macao harbor may be still a sink for POPs in the Pearl River estuary. The type of organic mater plays an important role on the distribution and accumulation of PCBs in different grain-size particles in sediments. The low chlorinated PCB congeners ( two to three chlorine atoms) seem to be associated preferentially with the fractions rich in amorphous organic matter, black carbon, clays and vegetal fragments, while the high chlorinated PCB congeners (four to seven chlorine atoms) show preferentially accumulated in the fractions abundant in coal-derived matters and coke carbon particles. The results from this project could be a great help for a better understanding of the risk of the two heavily polluted sediments.

以DDTs 和PCBs污染严重的伶仃洋西部和珠江广州河段水下沉积物为靶区，系统分析污染物组成和标志物特征，探讨高污染区的污染规律、类型、来源及其沉积环境和富集机制；研究不同深度水、悬浮颗粒物、水生生物和沉积界面上下颗粒物中难降解有机物的特征，探讨高污染区毒害有机物再释放的条件和环境危害。为控制和修复高风险污染区提供科学的依据。