DISTRIBUTION PATTERN OF HEAVY METALS IN THE SEDIMENTS OFF DONGYING COAST AND ITS ENVIRONMENTAL SIGNIFICANCE

Surface sediment samples collected from the offshore area of Dongying city are studied in this paper for sedimentology and heavy metals, by which environmental quality is evaluated. It is revealed that the surface sediments in the study area mainly include sand, silty sand, sandy silt, silt and mud dominated by silty sand and sandy silt. The sediments are getting finer off the coast towards the sea. The average contents of heavy metals Hg, Cd, Pb, Cu, Zn, Cr and As are 0.019, 0.12, 21.53, 22.4, 73.02, 67.02 and 12.77 μg/g respectively. The integrated pollution index of the study area ranges from 0.27 to 0.73, with an average of 0.43, all less than 1, indicating a rather clean environment. The ecological harm of heavy metal elements in surface sediments of the area is low, and the pollution degree is in an order of As>Hg>Cd>Cu>Pb>Cr>Zn.