Temporal And Spatial Distribution And Risk Assessment Of Three Pollutants In Water And Surface Sediments Of Yangzhou Urban Area

Organochlorine pesticides(OCPs),polycyclic aromatic hydrocarbons(PAHs)and polychlorinated biphenyls(PCBs)are three typical persistent organic pollutants(POPs)that are carcinogenic,teratogenic,and mutagenic.They can migrate long distances through various environmental media and cause great harm to human health and environmental safety.Surface water and sediments are important environmental receptors for pollutants such as OCPs,PAHs,and PCBs.Therefore,it is of great theoretical and practical significance to study exposure levels,environmental behaviors,and environmental risks of OCPs,PAHs,and PCBs in surface water bodies and surface sediments.For the first time,this paper systematically studies three types of typical POPs in the water and surface sediments of Yangzhou City.During the two years of 2016 and 2017,three types of POPs in the water and surface sediment samples from 13 sites in Yangzhou city were analyzed.Meanwhile,sources of OCPs,PAHs and PCBs were studied and risk assessment of these pollutants were given out.This study has important theoretical and practical implications for the control and reduction of related POPs pollution and the coordinated development of the regional economy and the environment.The concentrations of OCPs,PAHs,and PCBs in the surface water of Yangzhou City ranged from 33.58-468.33 ng/L,321.23-5422.60 ng/L and 0.56-41.63 ng/L,respectively.The average concentrations of OCPs,PAHs,and PCBs in the water of Yangzhou City were 133.07 ng/L,1015.975 ng/L and 9.44 ng/L,respectively.The total concentrations of OCPs,PAHs,and PCBs in sediments were 27.00-9419.22 ng/L dw,21.25-2284.67 ng/L dw,and 0.03-14.45 ng/g dw,and the average concentrations were 785.76 ng/g dw,656.85 ng/g dw and 1.195 ng/g dw.The distribution of OCPs,PAHs and PCBs in the water of Yangzhou CityCity was uniform.The concentrations of OCPs,PAHs and PCBs in the water in spring and summer were higher than those in autumn and winter.The distribution of the three types of pollutants in the surface sediments were not the same.The concentration of OCPs in surface sediments of S9 was significantly higher than in other 11 sites.The overall distribution trend of OCPs in sediments was:OCPs concentrations in City center>OCPs concentrations in westen City>OCPs concentrations in easten City.The seasonal variation of OCPs concentration in the surface sediments of each site was very small.The concentration of PCBs in the sediments of S9 and S13 was higher than the differences in the other 10 sites,and the quarterly differences in PCBs concentration in the surface sediments in each site were small.The concentration of PAHs in sediments of S4,S9,and S11 was significantly lower than that of other sites.The distribution trends of PAHs concentration in sediments was as follows:concentration of PAHs in easten City>concentration of PAHs in City center>concentration of PAHs in westen City.The quarterly changes of PAHs in sediments are obvious:the concentration of PAHs in spring>the concentration of PAHs in autumn>the concentration of PAHs in summer>the concentration of PAHs in winter.By analyzing the sources of OCPs,PAHs,and PCBs in the water of Yangzhou City,we found that the HCHs in the surface water was affected by the historical residues of pesticides and the use of lindane.The DDTs in the surface sediments mainly come from environmental residues.PAHs in water and sediments mainly originate from combustion sources.The main source of PCBs in water was the persistence of domestic PCBs in the environment,and the source of PCBs in sediments was mainly affected by domestic capacitors,transformers,and paint additives.The concentrations of PAHs and PCBs in the surface water and sediment of Yangzhou City were generally low,and the ecological risk of PAHs and PCBs in surface sediments from most sites is low.The concentrations of p,p'-DDE in sediments of S9 and S13 are relatively high,and there is a high ecological risk.The ecological risk of other sites is low.This paper focuses on the spatio-temporal distribution and source analysis of POPs and assesses their impact on ecosystems.This study is of great significance for the control and reduction of POPs,and the coordinated development of economy and environment.