Distribution Characteristics and Ecological Assessments of Heavy Metals in Surface Sediments of the Pearl River Estuary

In order to uncover the distribution and potential environmental risk in sediments of the heavy metal elements,Cr,Pb,Zn and Cu,fifty-seven surface sediment samples collected from the Pearl River Estuary are analyzed.The results show that the percentages of every elements are higher on west side of the Pearl River Estuary than the one on east side;however,they appear a clear descending tendency from northwest to southeast to south of the inner Lingding Island.There is a positive correlation between the percentages of the heavy metal elements and of the metal oxidations such as TiO2,MnO,Fe2O3,P2O5 and Al2O3,Furthermore,the percentage correlation is especially distinct between heavy metal elements and Fe2O3 and P2O5.Additionally the positive percentage correlation also exists between the heavy elements and content of the clay.According to the comparison with the past,current percentages of Cr,Pb,Zn and Cu have an increase trend gradually.Although the influences of heavy metal elements on the Pearl River Estuary are small,they possess a threat to the environment,and the relative pollution to the environment is PbCuCr Zn.