Study On Organochlorine Pesticides And Polychlorinated Biphenyls Of Surface Sediments In Jiaojiang Estuary

As one of the first confirmed persistent organic pollutants,PCBs and OCPs have the characteristics of difficult biodegradability,semi-volatility,and they can be transported and migrated over a long distance.Their highly toxicity and fat-solubility made them trend in bio-accumulation in adipose tissue and bio-magnification via food chain.They would pose a significant threat on the environmental and human survival and sustainable development.The paper investigated 9 organochlorine pesticides(OCPs)and 20 polychlorinated biphenyls(PCBs)of surface sediments in Jiaojiang Estuary in Taizhou City.The concentrations,spatial distribution and pollution source of OCPs and PCBs were analyzed,and the composition characteristics were discussed,the Enantiomeric fractions(EFs)value of chiral OCPs were determined.The pollution status and ecological risks of POPs in the study marine environment were also assessed.All the investigation would gain pollution status of OCPs and PCBs in Jiaojiang Estuary,provide more accurate scientific basis and theory support.The main conclusions in the paper were as follows:(1)The spatial distribution and source of OCPs in surface sediments of Jiaojiang Estuary were surveyed.The concentration range of ∑HCHs and∑DDTs were 0.65-1.72ng/g,1.86-34.31ng/g,with mean value of 1.01ng/g and 5.63ng/g,respectively.The HCHs of OCPs of sediments in Jiaojiang Estuary mainly came from historical residues.And most of DDTs were from earlier residues,the rest were from Dicofol insecticide still in use in this area.a-HCH of HCHs could be preferentially selective degradation of enantiomers.With comparison of other area at home and abroad,OCPs residual of sediments in Jiaojiang Estuary was relatively low,but according to ecological risk assessment proposed by Long,the OCPs residual of sediments in this area would pose a certain toxic effect on biological.(2)The spatial distribution and source of PCBs in surface sediments of Jiaojiang Estuary were surveyed.Total PCBs concentrations ranged from 4.93ng/g to 108.79ng/g(mean 29.08ng/g),with the highest value of PCBs was found at site 8(108.79ng/g).As the dilution and erosion of ocean currents,the concentration of PCBs gradually reduced.But when it reached to a "marginal filter"(the f area),the PCBs levels were significantly increased.Furthermore,the PCB homologue composition analysis roughly showed two different homologue patterns.The first group(G1),detected in site 1-8,was extremely dominated by tetra-PCB.The second group(G2),detected in the rest sites,showed a more or less uniform distribution of di-,tri-,pentra-and hexa-PCB.Principal component analysis.showed,the PCBs pollution in this area mainly due to industrial products Aroclor 1221 and Aroclor 1248.(3)Based on risk assessment criteria,the PCB concentrations(sum of seven PCB congers)exceeded the ERL(22.7ng/g)at eight sites,but were none more than the ERM(180ng/g)value in all sites of Jiaojiang Estuary.Of the sites above ERL,only one was from the outer part of the estuary,the others were all located in the inner part of the estuary.In the case of EAC,the concentrations of ∑7PCBs exceeded the criteria at ten sites,with eight of which situated in the inner part of the estuary.Therefor,the PCBs in sediments of Jiaojiang Estuary suggested possible adverse effects on the aquatic biota,especially for those from the inner part of the estuary.