| In order to investigated horizontal distribution patterns of heavy metals in surface sediments of Hongze Lake, heavy metal contents in every samples were measured by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Atomic Fluorescence spectrometry (AFS) and the potential ecological risks of each heavy metals were analyzed. The average contents of heavy metals Cu, Zn, Pb, Cd, Cr, Hg, As, Fe, Al and Mn are 34.99 mg/kg, 72.44 mg/kg, 18.82 mg/kg, 3.24 mg/kg, 57.59 mg/kg, 0.07 mg/kg, 23.67 mg/kg, 29.63 mg/g, 37.19 mg/g and 0.69 mg/g, respectively. Horizontal distribution patterns of every heavy metals (Cu, Zn, Pb, Cd, Fe, Al, Cr, Hg, Mn and As) in surface sediments were very similar. By impact of hydodynamical and topographical condition, the contents of heavy metals were significantly lower in the inflow river mouth areas than that of open water area in the eastern part of the lake, and that of bays and outflow river mouth areas. This distribution pattern belongs to Turbidity Flood Model. These heavy metals are highly related with each other positively, indicating that they are from the same pollution source. The geo-accumulation index (Igeo) and the Hakanson potential ecological risk index were applied for assessing the status of sediment heavy metal enrichment and the extent of potential ecological risk. The pollution extent of heavy metals followed the order: Cd>As>Cu>Cr>Zn>Hg>Pb, while the single potential ecological risk of heavy metals followed the order: Cd>As>Hg>Cu>Pb>Cr>Zn. The pollution extent and potential ecological risk of Cd were the most serious among all heavy metals. The distribution pattern of Cd individual potential ecological risk indices is exactly the same as that of general potential ecological risk indices for all heavy metals, indicating the important contribution of Cd in the general indices. Analysis showed that heavy metal pollution and the potential ecological risk existed in three risk regions: the central open water area and outflow river mouth region (S9, S1 and S8), the northern bay region (S6) and the western bay region (S5). |
