[Objective] This study aimed to investigate the existing forms and bioaccessibility of vanadium（V） from soil and mineral of Panzhihua region.[Method] The representative Xigeda soil and vanadium-titanium magnetite were collected from Panzhihua region to determine the existing forms of vanadium from soil and mineral;in vitro bionic digestion model was established to measure the bioaccessibility of vanadium.[Result] The dissolved concentrations of vanadium from farmland,mining area and vanadium-titanium magnetite in gastric juice were respectively 5.02,9.50 and 3.88 mg/kg,and the bioaccessibility ranged from 0.09% to 3.00%;the dissolved concentrations of vanadium in intestinal juice were respectively 2.98,5.43 and 4.49 mg/kg,and the bioaccessibility ranged from 0.10% to 1.78%.The content of vanadium in various existing forms varied significantly,the contents of vanadium in non-specific adsorption state and specific adsorption state were low,but residual content was completely high,which accounted for 75.06%,95.32% and 86.27% of the total content of vanadium in samples.[Conclusion] Bioaccessibility of dissolved vanadium in gastric juice was higher than that in small intestinal juice.Vanadium from soil and mineral was difficult to generate morphological transformation and migration,which was the main reason for low bioaccessibility.
[Objective] This study aimed to investigate the impact of vanadium at dif- ferent concentration on enzyme activity and microbial biomass in soils. [Method] Us- ing pot experiments in the growth cabinet, we would like to investigate the changes of the soil enzyme activity and microbial biomass at different growing stages of rape （Brassica juncea L.） at different soil vanadium concentrations （soil background value was 147 mg/kg, spiked with 0, 50, 100, 150, 250 and 500 mg/kg of exogenous vanadium）. [Result] Among all enzymes examined, polyphenol oxidase was most sensitive to soil vanadium. Addition of 50 mg/kg vanadium decreased its activity up to 56% of the control probably due to the vanadium toxicity. In comparison, the ac- tivities of sucrase, urease and catalase was less affected by soil vanadium. Surpris- ingly, the activity of sucrase, urease and catalase at the rape seedling stage differed significantly from at the maturity stage, highlighting the potential impact of plant growth on the vanadium-soil enzyme interaction. Different soil vanadium concentra- tions led to increases of microbial biomass to different extents. However, the corre- lation between soil microbial biomass carbon and phosphorus with vanadium con- centrations was insignificant. This revealed that the presence of additional factors （eg. plant） affected soil microbial biomass carbon and phosphorus aside from soil vanadium. [Conclusion] Polyphenol oxidase may be considered as an indicator of soil vanadium contamination. Due to the highly complicated interaction between vanadium and soil biological activities during plant growth, more investigations are required to reveal the mechanisms beyond our findings here.
