Characteristics and Risk Assessment of Heavy Metals in Uncultivated Arable Lands at Dongting Lake Basin, China

With a tremendous population but comparatively little arable land, uncultivated arable lands in China are a precious resource implementing the sustainable farming strategy to guarantee food security, but currently their quality is seldom monitored and assessed, restricting their safe crop production once the need for farming. Here, the pollution characteristics, risks, potential pollution sources, and early warnings of heavy metals (HMs) in uncultivated arable lands at Dongting Lake basin were evaluated. The results showed that higher ecological risk pollutants at uncultivated arable lands in the study area were Cd (1.11 mg/kg) and As (43.48 mg/kg) rather than other HMs, where Cd and As were derived from industrial production (20.35%) and agricultural activities (19.34%), respectively, indicated by qualitative and quantitative models. Children were more susceptible than adults to As and Cd loading in the study area by the probabilistic health risk assessment based on Monte Carlo simulation. The health risks assessed by bioavailable HMs significantly decreased, but there was still a non-negligible carcinogenic risk. The contents and risks of HMs would gradually decline under the optimistic scenario that the pollution inputs are zero under the strict environmental policy, while dramatically increase under the default condition that the pollution status maintains constant in the future. Results of this study would be expected to arouse the attention of the administration about the quality and safety of uncultivated arable lands and thus to implement indispensable remediation in the name of crop safety supply.