Estimating Background Concentration of Zinc in Paddy Soils with Various Methods and Identifying Areas with High Anthropogenic Zinc Input

Different methods were applied to recent soil survey data to estimate background concentration of zinc in paddy soils in central Anhui Province, China. Results with quite high consistency were obtained and a background concentration of 66.1 mg kg^-1 was accepted and used for calculating zinc surplus in soils and thereafter for identifying areas with high anthropogenic zinc input. Spatial characteristics of soil zinc surplus along the Yangtze River suggest that both anthropogenic emission and geogenic accumulation can be attributed to the zinc enrichment in paddy soils along the Yangtze River. High level soil zinc can be directly linked to metal-based industry in some special areas while medium-low level enrichment of soil zinc is the result of natural enrichment. Zinc also concentrated in soils of large urban areas via polluted irrigation water.