Assessing long-term environmental risks of trace elements in phosphate fertilizers.

The potential risks originating from arsenic and cadmium accumulations in cropland soils through the fertilizer applications have been public concern. A generalized trace element mass balance model was developed to evaluate the long-term fate and transport of arsenic and cadmium in cropland soils. Model simulation results showed that normal cropping practices do not have a significant effect on the total As content of the receiving soils, but the application of Cd-containing P fertilizers could, over time, cause Cd to accumulate in soil and therefore increases the risk of its transfer through the food chain. Regulations have been enacted in several states to set the maximum contaminant levels for arsenic and cadmium in fertilizers. The simulation outcomes indicated that some of the existing fertilizer regulations are not strict enough to prevent significant accumulation of Cd in cropland soils. Sensitivity analyses show the solid-solution partitioning coefficient, and the plant uptake factors are primary factors that affect the fate and transport of As and Cd in cropland soils. The uncertainty associated with assessing the fate of trace elements in cropland soils is due to the high variability of model parameters.