北海近岸海域表层沉积物中DDTs、PCBs的分布、来源与生态风险分析

Distribution,Sources and Ecological Risk Analysis of DDTs and PCBs in Surface Sediments of Beihai Sea Coast

关键词:  北海  沉积物  滴滴涕  多氯联苯  生态风险

Key words:  Beihai  sediment  DDTs  PCBs  ecological risk

摘要:

为评价广西北海市近岸海域表层沉积物中滴滴涕（DDTs）和多氯联苯（PCBs）的生态风险水平，于2017年8月使用挖斗式采泥器采集北海市近岸海域17个站点的表层沉积物样品，采用气相色谱法测定样品中DDTs （pp'-DDE、op'-DDT、pp'-DDD、pp'-DDT）和PCBs （三氯联苯PCB28，四氯联苯PCB52，五氯联苯PCB101、PCB112、PCB118，六氯联苯PCB138、PCB152、PCB153，七氯联苯PCB180和八氯联苯PCB198）的含量，分析其组分特征，并对沉积物中DDTs和PCBs进行生态风险评价。结果表明：北海近岸海域表层沉积物中持久性有机污染物（Persistent Organic Pollutants，POPs）平均含量（ng·g^-1，干重）为PCBs （3.08）>DDTs （0.89）；污染物等值线图表明近岸海域表层沉积物中的DDTs、PCBs含量高于远岸海域，DDTs含量高值区主要在北海港泊位及营盘港海域，PCBs含量高值区主要在北海港泊位、营盘海域及铁山港湾口海域。DDTs 4种同系物平均百分含量排序为pp'-DDE（46.4%） > pp'-DDT（21.8%） > op'-DDT（20.5%） > pp'-DDD（11.3%），pp'-DDE为沉积物DDTs中的主要成分；五氯联苯PCB101和七氯联苯PCB180为沉积物中PCBs的主要成分；所有站位中DDTs、PCBs的含量平均值均低于一类标准（GB 18668-2002），污染程度总体较轻；有17.6%的站位DDTs含量介于生态风险效应区间低值（Effects Range Low，ERL）和生态风险效应区间中值（Effects Range Median，ERM）间。北海市近岸海域表层沉积物中DDTs、PCBs残留水平生态风险总体较低。

Abstract:

To evaluate the ecological risk level of DDTs and PCBs in surface sediments of Beihai coastal area,Guangxi,in August 2017,the surface sediment samples from 17 stations in the coastal waters of Beihai City were collected by using bucket dredger,and the contents of DDTs (pp'-DDE,op'-DDT,pp'-DDD,pp'-DDT) and PCBs (trichlorobiphenyl PCB28,tetrachlorobiphenyl PCB52,pentachlorobiphenyl PCB101,PCB112,PCB118,hexachlorobiphenyl PCB138,PCB152,PCB153,heptachlorobiphenyl PCB180 and octachlorobiphenyl PCB198) were determined by gas chromatography.Their component characteristics were analyzed,and the ecological risks of DDTs and PCBs in sediments were evaluated.The results show that the average content of Persistent Organic Pollutants (POPs) (ng·g^-1,dry weight) in the surface sediments of the coastal waters of Beihai was PCBs (3.08)>DDTs (0.89).The contour map of pollutants showed that the contents of DDTs and PCBs in the surface sediments of the coastal waters were higher than those in the offshore waters.The high-value areas of DDTs content were mainly in the berths of Beihai Port and the sea areas of Yingpan Port.The high-value areas of PCBs content were mainly in the berths of Beihai Port,the sea areas of Yingpan Port and the sea areas of Tieshan Port.The average percentage of the four DDTs homologues ranked as pp'-DDE (46.4%) > pp'-DDT(21.8%) > op'-DDT(20.5%) > pp'-DDD(11.3%),and pp'-DDE was the main component of DDTs in sediments.Pentachlorobiphenyl PCB101 and heptachlorobiphenyl PCB180 were the main components of PCBs in sediments.The average content of DDTs and PCBs in all stations was lower than the first class standard,and the pollution degree was generally lighter.The DDTs content of 17.6% stations was between Effects Range Low (ERL) and Effects Range Median (ERM).The ecological risks of DDTs and PCBs residues in surface sediments of Beihai coastal waters were generally low.