关键词: 黑臭水体;底泥;重金属;污染评价;断面分层取样;

Abstract: The characteristic of heavy metal pollution in sediment is an important prerequisite for the comprehensive treatment of black-odorous water bodies.The sediments in Daligou of Xiangyang City were chose to investigate heavy metal pollution.Firstly，nine samples were collected by stratified sampling at three sampling sections，and the contents of cadmium，arsenic，lead，chromium，copper，zinc，nickel，and mercury were measured.And then the potential ecological risk index method and the geo-accumulation index method were used to analyze the characteristics and degree of heavy metal pollution.The results showed that：① The order of the single-factor potential ecological risk index from high to low was Cd，Hg，Pb，Cu，As，Ni，Cr，and Zn，and the comprehensive potential potential ecological risk index （RI） was above 440，which were up to the grievous level of ecological risk.② The order of the geo-accumulation index from high to low was Cd，Pb，Cu，Hg，Zn，Cr，Ni and As.③ The sediments were tested as serious cadmium pollution and the light arsenic pollution.Whereas the pollution level of the other heavy metal had some difference.④ It was also found that the heavy metals pollution of sediments in downstream was more severe than that in upstream，which was manifested obviously in the surface layer sediments.While in upstream section，the pollution was severe in lower layers，which indicated the secondary pollution of water body.

Key words: black-odorous water；sediment；heavy metal；pollution evaluation；sectional stratified sampling