[Temporal-spatial Distribution and Pollution Assessment of Dissolved Heavy Metals in Chaohu Lake].

Surface water samples were collected in different seasons from Chaohu Lake to determine the concentrations and potential environmental impacts of nine dissolved heavy metals (As, Hg, Cd, Cu, Pb, Zn, Cr, Ni, and Co). The concentrations of the selected heavy metals were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES, ICAP6000 series). The single pollution index method and integrated pollution index method were used to evaluate the potential environmental impacts. The results indicated that the contents of dissolved As, Cd, Pb, and Cr in Chaohu Lake were lower than the limitations of GradeⅠof the Environmental Quality Standards for Surface Water (GB 3838-2002), while Cu and Zn were within the limitations of GradeⅠ-Ⅱ and Hg was within the limitations of GradeⅠ-Ⅲ. The contents of Ni and Co were far below the limitations. The concentrations of the selected heavy metals (Cu, Pb, Zn, Cr, Ni, and Co) varied among seasons and areas. Elevated concentrations of Cu, Zn, and Ni were found in summer, while elevated contents of Pb, Cr, and Co were found in autumn, autumn, and spring, respectively. Trace elements in the western part of Chaohu Lake (especially in the northwestern part) were higher than those in the middle and eastern parts for autumn, winter, and summer. Significant positive correlations were found among Cu, Pb, Zn, Cr, and Ni in the surface water, suggesting that these elements may derive from similar sources. The values of both the single factor pollution index and integrated pollution index of the selected elements in the surface water were far less than 1, suggesting that the environmental impacts could be regarded as negligible. The integrated pollution indices in the western part of the lake were higher than those of the middle and eastern parts on a one-year timescale, and the integrated pollution indices in each lake area followed a pattern of wet season (summer) > normal season (spring and autumn) > dry season (winter).