Evaluate the Potential Bioavailability of Vanadium in Soil and Vanadium Titano-magnetite Tailing in A Mining Area Using BCR Sequential and Single Extraction: A Case Study in Panzhihua, China

Vanadium (V) is a widely distributed and potentially dangerous pollutant in soils. However, the extraction methods for bioavailability of V in soils have not been unified. This study focused on the assessment of BCR sequential and single extraction (8 extractants) methods to predict potential bioavailability of V in the tailing and soils. The total V concentration in the soil samples was 167.43 ± 14.92 mg·kg–1, and the total V concentration was 239.93 mg·kg–1 in the tailing. The available V (acid-soluble, reducible, and oxidizable phases) percentage extracted by BCR sequential extraction was low, which was 0.19–0.82%, 0.27–5.78% and 4.37–10.5% in the soils, respectively. Meanwhile, the content of V fractions in the tailing was 0.56% (acid soluble), 1.22% (reducible) and 4.37% (oxidizable). The residual fraction of V was a predominant ingredient in the soils (83.3–93.9%) and tailing (93.9%). Compared with the soil samples, the tailing sample extracted by single extractants has a lower available V content, which was 2.3% (DCB), 1.32% (HCl), 1.66% (HNO3) and 0.22% (C6H8O7) lower than the available V content in the soil samples, respectively. Furthermore, the correlation between soil properties and available V contents also discussed in this study. The V extracted by DPTA and C6H8O7 exhibited good correlation with the total V content and potential bioavailability of V extracted by BCR in the soils, suggesting that DPTA and C6H8O7 single extraction method might be an alternative to BCR sequential extraction to extract bioavailability of V in the soils. In addition, the potential ecological risks of V can not be ignored in this study area.