Bioaccumulation and Translocation Characteristics of Heavy Metals in a Soil-Maize System in Reclaimed Land and Surrounding Areas of Typical Vanadium-Titanium Magnetite Tailings

A total of 86 soil samples, 86 corn kernel samples, 50 tailings samples, and 33 ore rock samples were collected in reclaimed land and surrounding areas of typical vanadium-titanium magnetite tailings located in the Chengde Central Region and analyzed for 14 elements (P, Fe, Cu, Ni, Cd, Cr, Pb, Zn, Hg, Ti, Mn, and Mo) and speciation of heavy metals. This study investigated the bioaccumulation and translocation characteristics of heavy metals in a soil-maize system based on a descriptive statistical analysis, a geological accumulative index, bioconcentration factors, and a redundancy analysis. The results showed that the average accumulation index of surface soil followed an order of P>Cu>Fe2O3>Cr>Ti>V>Ni>Mn>Cd>Zn>Mo>As>Pb>Hg, while the accumulation level of heavy metals was generally categorized as either no accumulation or moderate accumulation. Compared to China's soil environmental quality standard risk screening values (GB15618-2018), the over-standard rates of Cr and Cu were 2.32% and 1.16%, respectively. The content of Fe, Ti, As, Pb, and Mn in the corn kernels of the tailings and surrounding areas was relatively high, and the content of Mo, Ni, Cu, Zn, Cd, and Cr in the control area was relatively high. The over-standard rates of Ni, Zn, and Cu in the corn kernels were 13.61%, 13.23%, and 5.17% respectively, according to China's national food safety standard limits for contaminants in food (GB 2762-2017). The bioconcentration factors of Fe, Ti, As, Pb, and Mn in the corn kernels of the tailings and the surrounding areas were relatively higher, while the bioconcentration factors of Mo, Ni, Cu, Zn, Cd, and Cr were lower than in control area. The bioactive components of Cd accounted for 50.17%, which was the highest, followed by Ni, Zn, and Cu with average ratios of 13.61%, 13.23%, and 5.17%, respectively. Compared to the control area, the Pb, As and Hg elements in the soil samples of the reclaimed land showed a lower total amount but a higher bioavailability content and soil pH value, while the Cu and Hg elements showed a higher total amount but lower bioavailability content and soil pH value. These differences in total heavy metal concentrations, bioavailability amounts, and soil pH values made the bioconcentration intensity of As and Pb in the tailings reservoir and surrounding area relatively higher. When studying the ecological risk of heavy metal pollution or determining the remediation target value of reclaimed land in a mine tailings reservoir and the soil around the mine area, the bioavailable state limit of heavy metals should be should be taken into account as the evaluation standard. © 2021, Science Press. All right reserved.