RISK EVALUATION OF HEAVY METALS IN THE SURFACE SEDIMENTS OF LAKE CHAOHU IN CHINA

In order to assess heavy metal concentrations in Lake Chaohu, which is one of the most polluted lakes in China, nine representative sampling sites were selected. Surface sediments from 0 to 20 cm were sampled with a Beeker sampler and total content of Cu, Zn, Pb, Cd and Ni in surface water was analyzed using flame or graphite furnace atomic absorption spectrometry. Sediment characterization mainly included acid volatile sulphide (AVS) and simultaneously extracted metals (SEM). The potential risk of heavy metals was assessed by several indexes: (1) Partition Coefficient (K-d), which is a ratio concentrations of a pollutant in sediment (Cs) and in water (Cw). (2) Sediment quality guidelines (SQGs), which provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems; and (3) SEM-AVS, which is the difference between the molar concentrations of SEM and AVS. The results indicated that Cu pollution and Cd pollution were serious, anthropogenic inputs were a more important factor, while the risk of heavy metal contamination was low.