| Zhelin bay is a large-scale maricultrue area in Guangdong province,and is the typical sem-closed maricultrue bay.Eutrophication,sulfide pollution and enrichment of toxic pollutants in sediment are increasingly serious due to the input of terrestrial industrial pollutants,the effect of ports and navigation and self-pollution of maricultrue in Zhelin bay.The organochlorine pesticides?OCPs?,polycyclic aromatic hydrocarbons?PAHs?and heavy metals draw particular attentions owing to their persitent pollution,ecological risk and human health risk.The distribution characteristics and pollution degrees of 20 OCPs have been investigated in surface sediments from the Zhelin Bay south of China and the ecological risk of OCPs and integrated ecological risk at the samples stations in sediments have been evaluated by risk quotient?RQ?and sediment quality guideline of NOAA.The possible sources of HCHs and DDTs in sediments were preliminary studied,and the correlation between OCPs and sediment characteristic parameters were discussed.The concentrations of DDTs in surface sediments were found to be higher than other OCPs,especially p,p'-DDD,and the concentrations of DDTs were higher than the limited values of Chinese Marine sediment quality criteria.The total concentration of 20 OCPs in surface sediments ranged from 14.14 to 306.88 ng·g-1,with a mean concentration of 78.37 ng·g-1,and the highest total concentration was at site 8?S8?.There were inevitable adverse biological effects and high ecological risk of p,p'-DDD and p,p'-DDT,high integrated ecological risk at S8 and S10.The possible sources of HCHs in surface sediments of Zhelin Bay were mainly from the application of Lindane pesticides.At S1,S2,S10,S11 there were the input of DDT into mariculture area of Zhelin bay,and at the other sites the sources of DDT were from the early residue in sediments or the long-term weathering sediments of using pesticides.There was a very significant positive correlation between HCHs,endosulfan,chlordane and dieldrin in sediments,while there was a negative relation between the above OCPs and TOC,which indicated that the presence of TOC could promote their biodegradation.There was a significant positive correlation between p,p'-DDD and Ca,which revealed that DDT used in the early period was deposited with biological carbonate.It was disadvantaged to accumulate OCPs in sediments that sediment particles increased gradually.The distribution of 16 polycyclic aromatic hydrocarbons?PAHs?was investigated in surface sediments from Zhelin Bay in south of China.The ecological risk of PAHs and integrated ecological risk at the sample stations in sediments were evaluated by risk quotient?RQ?and sediment quality guideline?SQG?of NOAA.The possible sources of PAHs in sediments were preliminary studied,and the correlation between PAHs and sediment characteristic parameters was discussed.This work was provided the scientific basis for controlling organic pollutants and managing environment.The total concentrations of 16 PAHs in surface sediments ranged from 71.03 to 148.64 ng·g-1,with a mean value of 107.87 ng·g-1,and for each PAH the mean concentration ranged from 0.50 to 18.49 ng·g-1.The values of RQERM,m ERM-Q and the most of RQERL were less than 0.1,which indicated that the ecological risk of this aquiculture area of the PAHs was not obvious.The possible sources of PAHs in surface sediments of Zhelin Bay were mainly from the oil,coal and wood combustion.The correlation analysis showed that the accumulation of PAHs in the sediments was associated with the sediment related parameters,such as TOC,the concentration of Ca and the size of the particles.A significant correlation between the PAHs with similar molecular weight was observed.The concentration,ecological risk,biological toxicity and human health risk were evaluated with the total amount and speciation distribution of heavy metals in the sediments of aquaculture area.The results showed that the enrichment degrees of Ni,Pb,As,Zn were high at most of the sampling sites,and the pollution of Ni was more serious in the cages and oyster breeding sites.By using the quality standard?SQGs?evaluation method,the As,Pb and Ni were at a high ecological risk in the sediment of the Zhelin Bay,and the northwest of the bay was at the highest ecological risk.By the Hakanson index method,the Cd,As and Hg were at moderate to strong ecological risk,and the sites around of the Xunzhou island were in the strong ecological risk evaluation.According to the RAC,the Cd was at the high ecological risk and the Ni at the moderate ecological risk.The harmful poisoning risk values were less than 150 mol/g OC by the evaluation method of the??NR-AVS?/?OC,which showed that there was no adverse effect in the sediment of the Zhelin bay.The HQ value was lower than 1 by the human health evaluation,which indicated that there was no potential health risks of exposure to metal by ingestion and inhalation and non carcinogenic risk of children.The main source of heavy metals was judged by the principal component analysis method,and the results showed that the gasoline and diesel combustion by ship was the major sources of pollution. |
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