Spatial patterns and variation of soil cadmium in Guangdong Province, China

A total of 260 soil profiles in Guangdong province were collected to investigate the spatial variation of soil cadmium concentration. In the study area, the soil Cd concentrations followed an appropriately lognormal distribution. The soil Cd geometric mean concentration of 0.04 mg kg− 1 is lower than that of China; however it varied from zero to 3.94 mg kg− 1. The upper baseline concentration of surface soils is 0.06 mg kg− 1. Soil samples with higher Cd concentration mainly are located in limestone and sandshale areas, and samples with lower Cd concentration are associated to granite areas. This phenomenon suggested that the soil Cd spatial distribution was primarily dependent on the properties of soil regional parent materials. Meanwhile, the present results indicated that there existed an obviously anthropogenic Cd input to local soils with high Cd concentration, such as the lead zinc ore exploitation, metal smelting, phosphatic fertilizer applications and vehicle exhausts.

Research Highlights
► In the study area soil Cd spatial distribution was primarily dependent on the properties of soil regional parent materials.
► Meanwhile, the present results indicated that there existed an obviously anthropogenic Cd input to local soils with high Cd concentration.
► The present results confirm that in the regional scale both soil organic matter content and pH have the significant correlation with soil Cd concentrations.
► The Cd movement export will take place constantly due to surface soil degradation and erosion.
► Its products containing Cd are being transported into ground and surface water.