Safety of heavy metals pollution for wheat planted in reclaimed mining soil

To keep the ecological safety of cultivated crops in reclaimed lands by filling mining wastes and fly ash into subsided lands, the paper took Liuxin mining area, Xuzhou in China as research area. The contents of heavy metals As, Hg, Pb, Cu, Cd, Cr, Zn in different parts of wheat planted in reclaimed soils and control soil were tested and compared. The distributions of Cd and Cr in different organs of mature wheat and enrichment coefficient of root were studied. Besides, the single index and comprehensive index methods were used to evaluate the risk of wheat grain. The results showed that Cd and Hg contents were lower in immature seedlings than in mature stems, Cr, Cu and Zn contents were higher in immature seedlings than in mature stems, while the content regularity of Pb and As were not too obvious. All heavy metals contents were lower in immature roots than in mature roots in reclaimed soils. With exception of Cr and Zn, all the other heavy metals contents were higher in immature roots than in mature roots in control soil. According to the food standard, Cr and Cd contents in wheat grain exceeded the standard. The risk assessment results showed the single pollution index of Cd and Cr of wheat grain reached middle to high pollution level, the comprehensive risk index of wheat grain was in the middle to moderate pollution level. The study has important practical value for grain safety monitoring in mining areas.