Evaluating the risk of heavy metals in the cultivated maize land around an abandoned coal mine in southwest Guizhou, China

Long-term mining activities in the past have caused heavy metals (HMs) pollution near the coal mining area in Xingren county, Guizhou province, China, while the status of HMs affecting the local soil, crops, and resident is unclear. Therefore, this study mainly revealed the status of HMs pollution in local farmland soil and in different tissues of maize through the ratio of secondary and primary phases (RSP), risk assessment code (RAC), accumulation factor (AF), transport factor (TF), potential ecological risk index (PERI), and health risk assessment. The results show that As and Pb contents in the soil exceed the limit values of Guizhou province and Chinese environmental quality in soil (GB 15618-2018). The lower RSP, RAC, and PERI values indicate a low HMs pollution level in soil. As, Pb, and Cr are the main contribution to the risk proposed by HMs, which are mainly through hand-mouth routes. The AF and TF values of Pb, Cr, As, Cu, and Zn are low in maize roots, stems, leaves, and grain. Hazard index of HMs exposure in maize grain for both adults and children exceed the acceptable range evaluated by health risk assessment model. The residual fraction is mainly HMs speciation in soil, followed by Fe–Mn oxide-bound, organic-bound, carbonate-bound, and exchangeable fractions. Our results suggest that although the total contents of HMs exceed the limited values, the lower AF and TF values are still lower in maize due to the relatively lower HMs activity in soil. Nonetheless, it is necessary to concern the HMs exposure in maize grain for both adults and children. Our suggestion is that Pteris vittata L. Pteris cretica, Pteris oshimensis, etc. maybe tried to restore the soil contaminated by HMs. The local government should formulate relevant policies to strengthen full process supervision and emergency response capabilities. This study provides a reference for HMs pollution remediation in local land and the analogous abandoned coal mines areas.