The distribution of heavy metals in surface sediment of Lake Dianshan and its correlations with macrozoobenthos

In the present study, the contents of seventeen heavy metals were determined using X-ray fluorescence spectrometry in Lake Dianshan sediments and their spatial distribution characters were analyzed. Håkanson's methodology was applied to determine the degree of contamination and the ecological risk of six heavy metals: Cd, As, Pb, Cu, Cr and Zn. The results showed that according to the contents, these heavy metals in the surface sediments followed the order as Al>Fe>K>Na>Ca>Mg>Ti>Mn>Zr>Zn> Sr>Rb>Cu>Cr>Pb>Ni>As. The potential ecological risk index showed that the heavy metals pollution risk was moderate in the Lake Dianshan sediments. According to the impact extent of the potential ecological risk, the pollutants could be ranged as Cu>As>Pb>Ni>Cr>Zn. The community structure and biodiversity of macrozoobenthos were investigated and additionally the correlations among the heavy metals and macrozoobenthos were analyzed. The results showed that except for Cr, there were highly significant positive correlations between the contents of the heavy metals. The contents of Cu, Zn and the potential ecological risk indexes of C_d, RI were highly correlated to the density of Oligochaete. Shannon-Wiener index and Margalef index had highly negative correlations with the contents of Pb and Ni.