Heavy Metal Emissions from Coal-fired Power Plants and Heavy Metal Pollution Characteristics and Health Risks in Surrounding Soils

Abstract

The aim of this study was to reveal the influence of heavy metal emissions from the flue gas of coal-fired power plants on the surrounding soil environment. Seven heavy metals, including As, Cd, Cr, Cu, Pb, Hg, and Ni, were detected in the flue gas of six coal-fired power plants in Shijiazhuang, and the heavy metals in the soil surrounding the power plants were analyzed. The source analysis and health risk assessment of the heavy metals were carried out. The results showed that after a series of flue gas pollutant control measures, the emission concentrations of different heavy metals in the flue gas of the coal-fired power plants ranged from 0.11 to 6.32 mg·(MW·h)-1, and Cu, Cr, and Ni were the main pollutants. The total amount of the seven heavy metal elements discharged into the atmosphere by each power plant was 33.56-275.71 kg·a-1. The average contents of Cr, Cu, Pb, Hg, and Ni in the surface soil surrounding the coal-fired power plant were higher than the background values of Hebei soil, and the contents were 1.16-2.32 times higher than the background values. The heavy metal content in the soil around the power plants was proportional to the heavy metal emissions in the flue gas. The heavy metal content in the soil under different wind directions first increased and then decreased gradually with the increase in distance from the power plants. Source analysis showed that coal combustion emissions contributed the most to heavy metals in soil around the power plants (41.4%), followed by industrial emissions (23.6%) and transportation emissions (19.6%). Altogether, human activities played a leading role in soil heavy metal enrichment, accounting for 84.6%. The health risk assessment showed that the overall health risk of metal elements in the soil surrounding the power plant was within acceptable limits.