Spatiotemporal variation of soil heavy metals in farmland influenced by human activities in the Poyang Lake region, China

The problem of heavy metal pollution in farmland has elicited growing concern in the Poyang Lake region, which includes the largest freshwater lake in China and serves as the country's commodity grain base. Here we determined soil As, Cr, and Hg concentrations and characterized their spatiotemporal distributions in the Poyang Lake region using data from 85 and 208 sampling locations that were respectively obtained by the farmland environmental quality surveys conducted in 1983 and 2010. The results showed that the average concentrations of these metals significantly increased from 10.72, 63.25, and 0.10 mg kg−1 in 1983 to 12.14, 84.06, and 0.13 mg kg−1 in 2010, respectively. From 1983 to 2010, the average As and Cr concentrations were higher and the Hg concentration was lower than background values, all of which met China's Soil Environmental Quality Standard (GB 15618-2018). Over the same period, the nugget/sill ratio for soil As and Cr each decreased but it increased for Hg, while for all three metals their ranges of the nugget/sill ratio increased. Spatial variation in soil of As, Cr, and Hg was mainly controlled by geological environment in 1983, whereas it was affected by human activities in 2010. To support the twin goals of sustainable utilization of farmland soils and food security, we should pay more attention to farmland pollution (e.g., heavy metals)—healthy soils for a healthy life.