Relationship between heavy metals and clay minerals in farmland soil around industrial zone and health risk assessment

Objective Aiming to understand the stability of heavy metal pollution, 100 surface soil samples were collected in farmland soil around industrial zone. Pb, Cr, As, Cd, and Hg were analyzed the total concentration, speciation and clay mineral.Methods The heavy metals of farmland soil around Wuji Tannery, Xinji tannery, Handan and Wuan Metallurgy, iron and steel, Guangping chemical plant and Neiqiu chemical plant pollution degree, stability and health risk of soil and wheat were evaluated by using single factor index method, soil mineral evaluation method and health risk assessment model.Results The results showed that Cr in Wuji tannery soil, Hg in Neiqiu and Guangping chemical Plant and Cd and Hg in Wuan Metallurgy were highly concentration. There was a significant correlation between heavy metals mainly in residual and clay minerals (Montmorillonite, chlorite, illite). Clay minerals had high retention for Cd, Hg. however, low retention for Pb and As. And Two soil samples from Wuji exceeded the Cr capacity of clay minerals. Human health risk assessments showed that soil exceeded a non-carcinogenic risk (1.02) to children by ingested as orally and skin. However, the cancer risk index with wheat as intake medium exceeded the tolerance limit (1×10^-4) for adults (5.16× 10^-4) and children (6.44 ×10^-4).Conclusions The positive relationship between heavy metals and clay minerals. Therefore, residents living on wheat as staple food in industrial areas should pay more attention to Cd content in wheat.