Heavy Metals' Accumulation And Risk Assessment In Surface Sediments Of The Oujiang Estuary

At Oujiang estuary area,We studied the content and distribution characteristics of heavy metals in surface sediments,application in Nemerrow index and potential ecological risk and evaluated heavy metal pollution in surface sediment,through the single factor analysis of Oujiang estuary area on parsing the distribution of heavy metal pollution.The main research results are as follows:(1)The Oujiang estuary area of 7 kinds of heavy metal element content in the sediment and the distribution were analyzed including Cr?Co?Ni?Cu?Zn?As?Pb.The results showed that Cr,Cu were higher than national Marine sediment quality standard,Co,As elements increased with the increased distance of trend in upside of Oujiang estuary.Cr,Zn,Pb element with the increase of the distance shows the tendency of lower levels while in the island,heavy metal elements on the overall trend with the increase of the distance lower levels.(2)Nemerrow index showed pollution degree of each heavy metal element in Oujiang,As,Co,Ni,Cu,Zn,Pb was different varide on upper head,Oujiang estuary and Dongtou islands.As had a higher comprehensive pollution level in Niyu-Yuanjue island,Co had a main pollution elements in upside of Oujiang estuary,The upside of Oujiang estuary and the Oujiang estuary had a higher level of the comprehensive pollution while Cu?Zn is lower than Damen island.(3)Potential ecological risk index in Oujiang from high to low showed the order: upside of Oujiang estuary > Oujiang estuary>Dongtou island.The Cr?Co?Cu?Zn?Pb potential ecological risk index of the upside of Oujiang estuary had higher than Oujiang.Ni,As had a higer potential ecological risk index in Oujiang,Dongtou island comprehensive potential ecological risk index were lowest.Dongtou island's comprehensive potential ecological risk were lower,Niyu-Yuanjue island had the lower level in nemerrow index and potential ecological risk index,because of the long distance.On both sides of the oujiang river pollution had certain effects on the island.(4)From the variation of heavy metal elements along the Oujiang estuary,Co,As of the upside of the Oujiang estuary had an increase content trend with increase distance.Pb had a weak migration ability,with the increase of distance and showed the tendency of lower levels.The content of Cr,Zn,Pb decreased with the increase of distance.In Dongtou island segment,Cr,Co,Ni,As elements island has decreased with distance of the Damen,While in Niyu-Yuanjue island these elements creases with the increased distance.In the sample points near the Dongtou island's,heavy metal element content is higher than that away from the upside of the Oujiang estuary.The heavy metal pollution of Dongtou islands is from human activities and island because the diffusion barrier of heavy metal pollution.(5)In Dongtou islands there is a greater difference between heavy metal content in different land use types,.most of the heavy metals are more than the soil background value of zhejiang province and Cr,Co are the main over standard elements.For different land types of soil,heavy mental potential ecological harm from strong to weak order is acquaculture area?reclamation area?the port area,forest area,farmland area.Correlation analysis showed that in reclamation area and the pork area heavy metal elements correlation is stronger than other types.In reclamtion area,As and Co?Cu have extremely evidently positive correlation(P<0.01),Pb and Zn have the same positive correlation(P<0.01),In port area,Cu and Co have a extremely evidently positive correlation(P<0.01),As,Pb and Zn have the same positive correlation(P<0.01).Cu and As content is higher in port area?acquaculture area and reclamation area.The different human activities in Dongtou islands had certain influence on the island of heavy metal pollution.Our study will be provide a science evidence basis for the regional pollution control and government.