The Distribution And The Potential Ecological Risk Assessment Of Heavy Metals In The Sediments Of Changli Ecological Monitoring Area In Hebei

Changli ecological monitoring area is located in the territory of Changli County,Qinhuangdao City.The research of grain size,organic matter,Pb,Zn,Cd,Cr,Ni Cu of sediments in the Changli ecological monitoring area,analysis of the particle size on the distribution of heavy metals and organic matter using correlation analysis.Several ecological assessment methods,which based on two different assessment systems(total concentration,sequential extraction),were applied to assess the heavy metals pollution and potential biotoxicity in sediments of Changli ecological monitoring area,the interrelationship of different evaluation methods were also discussedOverall,the distribution characteristics of Cu,Pb,Cr,Ni are the same.Cu,Pb,Cr,Ni content distribution of four kinds of elements in the study area in the south of the study area is greater than the northern part of the studyarea,mo stofthe high value area nearthe mouthofthe estuary and the lagoon;The distribution of Cd and Zn in the study area was higher in the northern part of the study area than the southern part of the study area;The high value area appears on the lagoon and near the estuary.The contents of Cu,Cd,Cr and Zn showed obvious decreasing trend in the direction of the offwards.The average contents of heavy metals in the sediments of C hangli ecological monitoring area was Zn>Cr>Ni>Pb>Cu>Cd.From the evaluation results,Cd is the main factor causing sediment pollution Pollution evaluationresults show that the Coastal waters of Changli ecological monitoring area overall at a low to moderate level of pollution,The relatively heavy pollution is in the coastal waters near the Dapu estuary and the east of the new opening.The modified BCR-sequential extraction technique was used to determine the speciation(acid-soluble,reducible,oxidisable and residual)of metals(Pb,Zn,Cr,Ni,Cu)in sediment samples of Changli ecological monitoring area.The results showed that Iron and manganese oxide-bound Pb accounts for 29.39%,Zn,Cr,Ni,Cu residues accounted for more than 65%;The iron-manganese oxide bounds of Cu,Pb and Ni were also positively correlated with their total dissolved contents.Pb,Cr,Ni and Zn were positively correlated with the total dissolved contents.The oxidation state of Cr and Ni is positively correlated with the total dissolved content.It can be seen that the total dissolved metal content will affect the correlation with the morphology of the content,the extent of its impact by the deposition environment and metal source constraintsBased on two different systems(based on the total amount of heavy metals and morphology of heavy metals)to evaluate the potential ecological risk of heavy metals in the marine ecological monitoring area in Changli,discusses the different evaluation methods.The specific evaluation methods used in this paper are as follows:the correction comprehensive index and potential ecological risk index,ratio of secondary phase and primary phase,secondary phase enrichment factor method.Based on the different evaluation methods,the potential ecological risk assessment of heavy metals in sediments of Changli marine ecological monitoring area showes that close to the new opening of 8#and 9#,16#and 17#near the the DaPu estuary and 15#farther away from the offshore with high potential ecological risk in the study area.The potential ecological risk of the 3#,6#,24#stations are the second,and the potential ecological risk of other stations is relatively low in the study area.