| Topsoil samples around the Guanting Reservoir ranging from 2～10km were measured for heavy metals concentrations. GIS and geostatistical techniques were applied to analyze the special variation and eco-environmental risk of heavy metals. The results show that Cd is the major contamination in this area, 3.4 fold higher than the national background level, with a mean of 0.68 mg/kg and a standard deviation of 0.17. The area in which Cd concentration is higher than the second level of national standard accounts for about 40% of the whole study area. Spacial variation of heavy metals (except Ni) mainly is induced by the stochastic factors-mostly anthropogenic activities, e.g. fertilizer application, cultivation and planting modes, etc. The spatial pattern of heavy metals approximately declines in the W-N and N-S direction, with the highest value in the region between Yanghe River and Huailai County. The complex contamination index of heavy metals has the same distribution as their concentrations. However, the complex eco-risk index with higher value mainly occurs in vicinities of Huailai County, Yanqing County and Beixinpu town. It suggests that the town with higher population density and industrialization will induce both environmental pollution and ecological risk. |
