Threshold criteria for heavy metals in the soils of hazard-free dry fruit production regions of China

Abstract

Determination of proper threshold criteria for heavy metals in soils is an important basis for hazard-free dry fruit production in China. Based on the detection of heavy metal contents in soils in this study, it is initially concluded that the soils for dry fruit production in China are suitable for hazard-free growing. Moreover, the soil safety qualification for dry fruit production is much better than that in some developed countries or regions, which might help our production have a competitive advantage on the international market. However, soil Cr contents in the country are slightly higher, so that it is necessary to take steps to control any contamination during the whole chain of production. The following threshold criteria for heavy metals in soils is suggested according to physical, ecological and economical considerations: Hg 0.15 mg/kg; As 20 mg/kg; Pb 50 mg/kg; Cd 0.30 mg/kg and Gr 200 mg/kg.