Study On Speciation And Distribution Of Heavy Metals In Surface Sediments From Anhai Bay And Weitou Bay,Fujian Province

The coastal area is the place where the most population gather and the economy develop fast.In recent years,the coastal area was affected seriously by the pollution.People pay more attention to the environment of coastal sea.The heavy metal pollution in sediments is one of the important indicators for monitoring the environment of coastal area.We had determined the heavy metals in surface sediment from Anhai Bay and Weitou Bay,Fujian Province.We want to know the source,the distribution,chemical speciation and the bio-availability of the heavy metals(Cr,Co,Ni,Cu,Zn,Cd,Pb)in surface sediment in autumn and spring from the study area.And we also assessed the pollution and the potential ecological risk of heavy metals in surface sediment from the study area.The main results are followed.In autumn,the distributions of the concentration of the measured heavy metalsshowed a decreasing tendency from the Anhai Bay to Weitou Bay,from the northwest to the southeast.The distribution of the concentration of the heavy metals in spring was the same as that in autumn,with slight increase in the southeast where near the Jinjing town in the study area.However there is no obvious trend in the distribution of Co in spring.The results of principal component analysis showed that:In autumn,the population from the surrounding factories and lives was the main source of the heavy metals without Pb.And the shipping was the source of Pb.In spring,that the sources of Cr,Cu,Zn,Cd,Pb were controlled by the anthropogenic input,which the source of Ni was dominated by both weathering and the anthropogenic input,and weathering mainly controlled the source of Co.The results of the heavy metals speciation(acid-soluble,reducible,oxidizable,residual form)showed that:In Anhai Bay,Cr,Co,Ni,Zn in surface sediment in autumn were existed in residual state.Cu?Pb were main in the reducible form.Cd was existed mainly in the acid-soluble and residual forms.In spring,the average concentrations of oxidizable and residual forms of Cr were similar,and the accounting for approximately 80%.The average concentrations of acid-soluble and residual forms of Zn were also silimar,and the accounting for approximately 80%.Co?Ni were existed mainly in residual form.Cu?Pb were existed mainly in the reducible form.Cd was mainly in acid-soluble form.The distributions of heavy metals speciation in autumn and spring were the same.The heavy metals were existed mainly in the residual forms,with Pb in the reducible form.We used many ways to assess the pollution degree and potential ecological risk of heavy metals.First,we used the way of Marine sediment quality.The results showed that:In Anhai Bay,the concentrations of Cd and Pb in all of the sampled stations in autumn and spring were in the first standard of marine sediment quality.And there were 12.5%,25%,75%of the all studied stations in autumn in which the concentrations of Cr,Cu and Zn were met the first standard of marine sediment quality,sequential.The concentrations of heavy metals from the stations which were in the proportion of 50%,16.7%,16.7%,met the first standard of marine sediment quality.In Weitou Bay,the concentrations of Cd and Pb in all of the stations in autumn were in the first standard of marine sediment quality.There were 85.7%,92.9%,92.9%of the stations in autumn in which the concentrations of Cr,Zn,Pb were met the first standard of marine sediment quality.The concentrations of heavy metals in all of the sampled stations spring were in the first standard of marine sediment quality,and there was the 54.5%of the stations in the concentration met the first standard of marine sediment quality.The study area is mainly contaminated by Cr and Cu.Second,we used the way of potential ecological risk index to assess the potential ecological risk of heavy metals.There was a strong ecological risk in autumn and spring in Anhai Bay.There was a moderate ecological risk in autumn and spring in Weitou Bay.Third,the results of ratio of secondary phase and primary phase(RSP)showed that:Except for Cd,the case of autumn was the same as the spring in Anhai Bay.The heavy metals were in the slight pollution degree,with Cu in moderate pollution degree,with Co in non-pollution.And Cd in spring was in the moderate pollution degree.The case of autumn was also the same as the spring in Weitou Bay.The heavy metals were in the non-pollution degree,with Pb in the slight pollution degree.