Pollution status of agricultural land in China: impact of land use and geographical position

According to the Soil Pollution Prevention and Control Action Plan released in May 2016, the soil quality of 666 666.7 ha of agricultural soil requires remediation before 2020. Despite the survey on the environmental quality of soil in China released in 2014, detailed data on current pollutant concentrations remain unavailable. To date, reports on soil environmental quality on the national scale are few. The current research aimed to gain a detailed understanding of soil pollution in China through literature study and data analysis. Data for eight potentially toxic elements (i.e., arsenic (As), cadmium (Cd), zinc (Zn), chromium (Cr), mercury (Hg), copper (Cu), nickel (Ni), and lead (Pb)) and two organic pollutants (i.e., hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethanes (DDTs)) were collected from 367 areas involving 163 prefecture-level cities. Principal component analysis and clustering analysis were conducted to understand the relationships among pollutants. Results indicated that organic pollution was less severe than inorganic pollution. In terms of land-use types, garden soil showed the heaviest pollution, followed by arable land and woodland. Regarding geographic distribution, the south central and southwest areas displayed heavy pollution. Principal component and clustering analyses revealed that As, Hg, HCH, and DDTs were mainly contributed by anthropogenic sources; Cr, Cu, Ni, and Zn were primarily caused by natural background; and Cd and Pb were contributed by both sources. The soil pollution status varied among land-use types and geographic areas. The implementation of proper remediation strategies requires detailed investigations on soil environmental quality.