The spatio-temporal variations of heavy metals in the sediment of Lake Fuxian and the contamination assessment

Abstract

Concentrations of metals in the surface and core sediments of Lake Fuxian were determined. The spatio-temporal features of contaminations Cr,Cu,Ni,Pb and Zn were discussed,referencing to the enrichment factor method and the chronology of the sediment core. Potential eco-risks of the heavy metals in the surface sediments were discussed on base of combining the potential ecological risk index and sediment quality guideline assessments. The results showed that metal concentrations exhibited some spatial variations with general higher concentrations in the near shore area than in the lake center. Concentrations of Pb and Zn have increased typically since the mid-1980 s,whereas concentrations of Cr,Cu and Ni have decreased. Pb and Zn should be influenced by human contamination as indicated by the hierarchical analysis and the enrichment factors. The metal contamination began at the mid-1980 s and showed an increasing trend. Enrichment factors of Pb were between 1. 6-4. 1 and Zn between 1. 4-2. 6 in the surface sediments,reflecting minimal to moderate contamination levels,where the values were decreased from the north lake to the south. Moreover,the sediment in the near shore region of the north lake was also contaminated with Cr. The riverine input should be also a reason for the heavy metal contaminations in the sediment of Lake Fuxian,additionally the atmospheric deposition. Metals Cr,Cu,Ni,Pb and Zn in the surface sediments may have low potential eco-risk estimated on the potential ecological risk factor.However,the metals may be of a moderate potential eco-risk according to the potential ecological risk index,which is consitent with that from a baseline of the sediment quality assessment.