Distribution and bioaccumulation of heavy metals in aquatic organisms of different trophic levels and potential health risk assessment from Taihu lake, China

Aquatic organisms of different trophic levels were taken from Taihu lake. Heavy metals (Cu, Zn, Cr, Ni, Cd, Pb) were measured in phytoplankton, zooplankton, in two species of zoobenthos, and in eight fish species, as well as in the water column and bottom sediments. Results showed that the concentration of Cu and Zn for all organisms was much higher than for other metals, and Cd was the lowest in all species. Generally, heavy metal concentrations in phytoplankton were higher than in zooplankton. In zoobenthos, the concentration in Bellamya sp.(human edible snail) was higher than that in Corbiculidae (bivalve). Metal concentrations had no significant difference between fish species but tended to be higher in predator fish such as Coilia ectenes and Erythroculter ilishaeformis than in herbivorous fish. The level of measured metals in Taihu fish was moderate-low compared with that of fresh water fishes from international results. Spatially, metal concentrations in organisms were higher in the north and west Taihu lake but lower in south and east lake and this appears to be related to river inputs that are heavily influenced by anthropogenic activities. The bio-concentration factor (BCF) for all aquatic organisms in the food chain indicated that it was generally highest in planktons, followed by zoobenthos, and lowest in fish. Health risk assessment and comparison with national and international standards showed that consumption of aquatic products from the lake was generally safe but fishermen were a higher risk group especially through dietary intake of Bellamya sp.

► All comments by the three reviewers have been revised and responded. ► Significance and implications of the study and its findings are emphasized. ► Sampling and discussion section are more detailed and in a deeper and broader context. ► Results are more precisely presented and separated from discussion.