Survey and assessment of metals distribution in the overlying water of the representative lake and rivers in Zhenjiang, China

In the current study, overlying water samples were collected from 21 sampling sites in representative lake and rivers in Zhenjiang, China, during winter and summer. The concentrations of As, Cd, Cr, Cu, Pb and Zn were determined, and the pollution index was assessed using single-factor and Nemerow pollution indices. Results showed that (1) the average As, Cd, Cr, Cu, Pb and Zn concentrations were 3.75, 0.50, 2.25, 3.33, 1.30 and 21.92 μg/L in the winter samples and 3.62, 0.40, 1.91, 2.72, 1.23 and 30.76 μg/L in the summer samples, respectively. The concentrations of these elements were within the concentration ranges of published data on rivers or lakes in China. (2) ANOVA revealed obvious spatial, not seasonal, variations in the overlying water in this research area, except for Cd and Zn. (3) The single-factor and Nemerow pollution index values were below 0.7 in all sites in the winter and summer samples, indicating that the water body had not been affected by As, Cd, Cr, Cu, Pb and Zn yet; the water quality was relatively good and free from the influence of these pollutants. (4) A significant correlation was found amongst As, Cd, Cr, Cu and Pb (P < 0.01). No significant positive or negative correlations were obtained between Zn and other heavy metals (P > 0.05), except for Zn and Cu (P < 0.05) in the winter samples. Principal component analysis (PCA) verified that As, Cd, Cr, Cu and Pb had similar distribution patterns. The correlations and PCA results indicated that the possible source of As, Cd, Cr, Cu and Pb was geochemical role, whereas complex original sources caused by human activities may have affected Zn concentrations in this research region.