Safety assessment and application of iron and manganese ore tailings for the remediation of As-contaminated soil

Iron ore tailings (FeT) and manganese ore tailings (MnT), which are abundant and inexpensive materials that contain many trace elements, were employed for the remediation of As-contaminated soil to mitigate As accumulation in rice under greenhouse conditions. Prior to the experiments, the toxicities of both amendments were assessed with the toxicity characteristic leaching procedure (TCLP) and horizontal vibration method (HVM). Based on the assessment results, both amendments were pretreated until no As was present in the leaching solution. After application of both amendments to the soil, the soil pH increased significantly (p < 0.05). The ranges of As concentrations in husk and brown rice samples were 0.13–1.54 mg kg−1 and 0.06–0.42 mg kg−1, respectively. The lowest concentrations of As (0.06±0.02 mg kg−1) in rice grains were observed with MnT treatment, which was related to the structure and composition of MnT. There was a significant negative relationship (p < 0.05) between Mn and As in rice plants, while there was a significant positive relationship (p < 0.05) between Fe and As in rice plants as well as the ratio of Fe/Mn and As in rice plants. In conclusion, MnT could potentially be useful as an amendment to remediate As-contaminated soil and control As uptake by rice plants.