The Characteristic and Assessment of the Heavy Metal Pollution in Ponds sediment of Nandu River in Haikou City

Using Nemero pollution evaluation method and GIS, the content, the pollution condition, the spatial distribution characteristics and the pollution reason of the 8 kind of different heavy metal elements(Cu、Zn、Pb、Cd、Cr、Ni、As、 Hg)in ponds sediment of Nandu River in Haikou city were analyzed. The result shows:(1) Among the surveyed heavy metals, Cd and Cu account for the key pollutants. The average value is 0.43 mg·kg-1and 78.60 mg·kg-1, respectively. The exceeded amplitude is 41.51% and 36.71%, respectively.(2) The overall evaluation result shows most of heavy metal pollution in the sediment is light pollution and moderate pollution. The area of the light pollution level and below account for a total area of 74.20%. The area of the moderate pollution level and below account for a total area of 25.80%. Sediment of heavy metal pollution has strong spatial heterogeneity; The variation coefficient of 6 kinds of heavy metal content in upstream is greater than the variation coefficient in downstream. The average values of Pb and As in upstream are higher than the average values in downstream, but the average values of Cr、Ni、Cu、Zn、Cd、Hg are the opposite, the Pollution degree and Pollution area in downstream are bigger than the in upstream.(3) The results of evaluation of Hakanson poten- tial ecological show that, The Cd and Hg elements have some potential ecological risk, and the sediments are in slight ecological risk level.(4)High content of heavy metals of the nearby soil and the soil parent material in the area, high content of heavy metals of rubble in the quarry near the river are the key reasons that the sediment exceed normal. There we suggest making use of the sediment reasonably according to different soil pollution degrees.