Ecological Assessment of Heavy Metals in Sediments from Jianhu Lake in Yunnan Province, China

Cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) in the sediments of Jianhu Lake were measured by an inductively coupled plasma-optical emission spectrometer (ICP-OES) to determine their spatial distribution characteristics and ecological risks. The results showed that the average concentrations of Cd, Cr, Cu, Pb and Zn in surface sediments (0-5 cm) were 0.41 +/- 0.34, 143.89 +/- 90.07, 46.14 +/- 30.08, 56.38 +/- 45.71, and 146.52 +/- 96.50 mg/kg, while those in core sediments (0-75 cm) were 0.51 +/- 0.44, 228.35 +/- 174.52, 89.94 +/- 74.63, 74.92 +/- 65.69, and 208.89 +/- 171.55 mg/kg, respectively. The total concentrations of heavy metals were highest in the western area of Jianhu Lake, and were higher in the bottom layer (70-75 cm) than in the surface layer (0-5 cm) in the entire Jianhu Lake region. The potential ecological risks of Cd in sediments were greatest, and the comprehensive potential ecological risks of the five tested heavy metals in sediments were highest in the western area of Jianhu Lake. Using the geoaccumulation index (I-geo), we found that pollution in sediments due to Cr was the most serious of all the heavy metals, and the degree of pollution due to these five heavy metals in each area varied greatly in Jianhu Lake. In addition, we found that the short-term release contribution of Pb and Zn was large, while both the short- and long-term release contributions of Cr were small.