Abstract: The National MultiPurpose Regional Geochemical Survey (NMPRGS) project has provided higher density and more systematic geochemical data of surface and deep sediment from more than 150 freshwater lakes in China. This paper builds on the information obtained from the NMPRGS project and presents the geochemical background values of lake sediments for As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, TN, TP, TOC and pH for the national freshwater lakes in China. Statistics show that the heavy metal elements As, Cd, Hg and TP, TOC have been accumulating significantly in the surface sediments, indicating changes in lake sediment quality across the country caused by extensive human activities. In this paper, we also discussed the uncertainties in risk assessment using existing international sediment guidelines. Therefore, efforts should be made on establishing the sediment quality guidelines for China. Such guidelines should take full consideration of geochemical background of chemical elements in freshwater lake sediments in China, and is critical for the improvement of lake environment management and pollution prevention & control in the country.

Key words:  geochemical background, freshwater lake, sediment, sediment quality guideline