Bio-accessibility and mobilization dynamics of soil vanadium during a 48-year vegetation restoration in a vanadium titano-magnetite tailings reservoir

• Published in: Science of The Total Environment
• Main Authors: Long, Zhijie, Zhu, He, Bing, Haijian, Ma, Zhongjian, Yu, Daming, Zhang, Wenwen, Wu, Yanhong
• Format: Report
• Language: English
• Published: ELSEVIER 2024
• Subjects: Heavy metals; Environmental risk; Vegetation restoration; Diffusive gradients in thin films (DGT); DGT-induced fluxes in soil (DIFS); CHURCHILL RIVER ESTUARY; 3 GORGES RESERVOIR; THIN-FILMS DGT; DIFFUSIVE GRADIENTS; RIPARIAN SOILS; SEDIMENTS; KINETICS; RELEASE; CADMIUM; SPECIATION; Environmental Sciences & Ecology; Environmental Sciences; Churchill River
• Online Access: http://ir.imde.ac.cn/handle/131551/57661; https://doi.org/10.1016/j.scitotenv.2023.167507

Bio-accessibility of vanadium (V) in soils determines the effectiveness of vegetation restoration in the vanadium titano-magnetite tailings reservoirs because of persistent V toxicity, yet the variations in the bio-accessibility and mobilization of V in the soils with vegetation restoration remain elusive. Here, the bio-accessibility and mobilization of V in the soil-water interface were investigated along a 48-year vegetation restoration chronosequence in the Majiatian tailings reservoir using the diffusive gradients in thin films technique (DGT) and DGT-induced flux model. We found a low concentration of DGT-extracted V along the vegetation restoration chronosequence and the V fraction was dominated by the residual form, indicating a low V bio-accessibility in the soils. The bioaccessibility of V increased along the chronosequence because of the increased V resupply from solid phase, especially from the organic V fraction and the clay bound V. Low supply coefficient (R = 0.25) revealed a limited release of V from solid phase to soil solution. The kinetic resupply processes of V and its key regulating parameters were stage-specific during the vegetation restoration. The pool size of labile V in the soils determined the rapid V supply at the early and late stages, while the low desorption rate of V from the solid to liquid phase regulated the slow supply regime at the middle stage. The results of the present study highlight the importance of the long-term monitoring of soil V mobilization in the tailings reservoir because of the increased bio-accessibility and the dynamic supply of V during the vegetation restoration.