Assessment of soil and maize contamination by TE near a coal gangue-fired thermal power plant.

Abstract

Coal preparation by-products, such as coal gangue, are inferior fuels enriched with trace elements (TEs). Owing to the issues surrounding the disposal of coal preparation by-products and energy shortages, Chinese researchers have strongly advocated harvesting energy from by-products. However, the secondary environmental pollution caused by such by-products has been overlooked. In this study, we aimed to assess the contamination of soil and maize (Zea mays L.) near a coal gangue-fired power plant (CGPP) in Liupanshui City, Guizhou Province, China, by TEs. The contents of 11 TEs (Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, V, and Zn) in soil samples and different maize tissues were measured, and their chemical speciation in soil was also determined. The results showed that the soil in the study area was polluted by the above elements to varying degrees at a very high potential ecological risk. The Cr and Pb levels in niblets of partial samples exceeded the Chinese food safety standards. The TE contents of maize tissues largely depend on the bioavailable fraction of the same elements in the soils, rather than their total contents. Pearson's correlation and hierarchical cluster analyses resulted in three clusters:(1) Pb-Zn-Cd; (2) Co-Cu-Mn-Sb-V-Be; and (3) Cr-Ni. Coal preparation by-products should not be directly combusted without pre-treatment. These results will aid readers and engineers in understanding the adverse effect of CGPPs and provide regulators and policymakers with relevant data to scientifically guide the utilisation of coal preparation by-products.