ANALYSIS OF HEAVY METALS SOURCES AND ASSESSMENT IN SEDIMENTS OF ULANSUHAI LAKE, CHINA

In order to understand the sources of heavy metals and their environmental risk in sediments of Ulansuhai Lake, concentrations of Cu, Fe, Mn, Zn, Pb, Cr, Cd, Hg and As were measured. Samples were taken at 33 positions in January and July 2009 and December 2010. Principal component analysis (PCA) was used to identify the different sources. To evaluate the potential risk and draw possible ecological risk index distributions, harm Hakanson and ArcGIS9.2 were applied with the potential ecological risk index classification standard to quantitatively calculate ecological risk classification area. The results demonstrated that concentrations of Cu, Fe, Mn, and Cr were mainly controlled by parent rocks; Pb, Zn and Cd were affected by industrial pollution. Meanwhile, concentrations of Hg and As were affected mainly by agricultural non-point source pollution and atmospheric settlement. Potential ecological risk analysis showed that potential ecological risk index in summer and winter was 337.37 to 869.03 and 177.45 to 685.58 and mean value were 572.67 and 389.73 respectively. Potential ecological risk indexes of area in level II, III and IVaccounted for 1.88%, 96.2%, and 1.92% of total area in winter and 0%, 52.9%, 47.1% in summer, respectively. The risk index of winter was high, and the majority was in the III level, however, nearly half of the area was at its highest level in summer, so the sediments had serious ecological risks in summer. Hg, Cd played contributed the main pollution factor, so, reducing waste water that contains mercury waste gas discharge and fertilizer loss is necessary to control heavy metal pollution in Ulansuhai Lake.