Soil pollution assessment and source identification of paddy soil in a typical polder of Dongting Lake

Abstract

Heavy metals are primary pollutants in agricultural soil that hinder the sustainable development of agriculture. To investigate the distribution characteristics and sources of heavy metal pollution of paddy soil in a typical polder of Dongting Lake, we collected 31 topsoil samples to measure the heavy metal content and soil pH. Based on the results, cadmium (Cd) exhibited the most severe soil pollution, followed by arsenic (As), lead (Pb), mercury (Hg), copper (Cu), and zinc (Zn). In terms of the potential ecological risk, Cd also posed the most significant threat, followed by Hg, As, Pb, Cu, and Zn. Most of the study area was heavily polluted and had moderate ecological risk. The main pollution sources were of lithogenic (30.5%) and anthropogenic origins (sewage irrigation [17.8%], atmospheric deposition [27.7%], and chemical fertilizers [23.9%]). Our findings indicate that controlling Cd contamination in the study area is a priority; the contaminations of Hg, As, and Pb also need to be controlled. This study provides scientific support for the environmental management and pollution control of paddy soil heavy metals in polders of South Dongting Lake in China.