Heavy metal contaminations in soil-rice system: source identification in relation to a sulfur-rich coal burning power plant in Northern Guangdong Province, China

Heavy metal contents (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in 99 pairs of soil–rice plant samples were evaluated from the downwind directions of a large thermal power plant in Shaoguan City, Guangdong Province, China. Results indicate that there is a substantial buildup of As, Cd, Cu, Pb, and Zn in the predominant wind direction of the power plant. The significant correlations between S and heavy metals in paddy soil suggest that the power plant represents a source of topsoil heavy metals in Shaoguan City due to sulfur-rich coal burning emissions. Elevated Cd concentrations were also found in rice plant tissues. Average Cd (0.69 mg kg−1) and Pb (0.39 mg kg−1) contents in rice grain had exceeded their maximum permissible limits (both were 0.2 mg kg−1) in foods of China (GB2762-2005). The enrichment of Cd and Pb in rice grain might pose a potential health risk to the local residents.