Trace metal enrichment in agricultural soils of Jianghan Plain

Abstract:

Coal consumption in China is increasing annually due to constantly rising energy demand. As a result, a massive amount of coal combustion byproducts, particularly in the form of fly ash, are expelled from power plants and distributed through atmospheric transport. The fly ash is eventually deposited on to land, potentially contaminating agricultural soils. Coal fly ash contains high concentration of a suite of toxic trace metals including lead, chromium, and arsenic. In this study, we surveyed the concentration of trace metals in agricultural soils at 131 sites within a 20 km radius of Yangluo Power Plant, a 2400 MW plant within the highly populated Jianghan Plain of Central China. Using X-ray fluorecence (XRF) spectrometry, the total concentration of trace metals in homogenized surface and subsurface soil samples were measured to calculate the corresponding enrichment factor at each site. Our initial findings demonstrate that Pb is enriched in a majority of sites, independent of land use, whereas As and Cr are generally not enriched in this region. Further studies using Pb isotopes as a source-tracing tool will help determine the Pb pollution’s origin. Ultimately, the results of this study may inform whether crops grown within the Jianghan Plain have the potential of being contaminated by metals emitted from coal power plants.