| Based on the Aureobasidium pullulans F4isolated from the rhizosphere of Hippochaete ramosissimum in Tongguanshan mine wasteland in Tongling, Anhui province, our study is trying to test the soluble phosphorus ability with various phosphorus sources of calcium phosphate (Ca-P), aluminium phosphate (Al-P), ferric phosphate (Fe-P) and rock phosphate (RP) by the research of pH, dissolved phosphorus, phosphorus in the bacteria and organic acid in the solution. Furthermore, the bacteria was fertilized to the mine tailing together with the phosphate rock to discuss the influences of tailing improvement effect on Vicia faba by the measurement of the shape, composition and nutrient amounts, moreover to determine the adaptation ability of Vicia faba in harsh environments and its prospective value of ecological remediations.The results based on the four kinds of phosphorus sources showed that the amount of phosphorus dissolved reached up to200mg·L-1, and the phosphorus solubilities of F4varied with the trend Al-P> Fe-P and Ca-P>RP. The pH of the culture solution dropped immediately within48h and pH fall range in solutions with Al-P and Fe-P was more evident than the value in solutions with Ca-P and RP. The main organic acids produced by F4were oxalic acid, citric acid and tartaric acid, and oxalic acid was the dominant composition. Phosphate solubilization of F4showed no significant correlation with the organic acid, but significantly correlated with the pH. Dissolving experiments with mineral phosphorus in Cu tailings showed that Olsen-P content in the tailings increased significantly by inoculation of F4and glucose simultaneously, indicated the potential application values of F4in ecological remediations of Copper mine tailings.The results of planting experiment showed that Vicia faba could improve the pH of tailing, and the conductivity was reduced to more than half, indicating that the planting of Vicia faba could effectively control the oxidation of metal sulphide in tailings. The content of available phosphate and effective nitrogen in the tailings increased significantly by the planting of Vicia faba, along with the urease, phosphatase, catalase and dehydrogenase activities increase, in which the dehydrogenase activity raised in the most range. In conclusion, Vicia faba adapted well in severe conditions and was appropriate for ecological remediations in the tailings.The influence of Vicia faba planting on different kinds of heavy metals varied. Available Fe and As activities were inhibited with no significant differences, while Zn, Pb, Cu and Cr activities were inhibited with significant differences. The addition of RP raised the pH of tailings substrates and changed heavy metal shapes. The enormous surface of RP was good for the absorption of heavy metals.Besides, phosphorus released from RP could combine with heavy metals and restrain metal activities except As suggesting prospective ability of tailing restorations. By contrast, the pH of tailings substrates decreased by the adding of Aureobasidium pullulans resulting in the raise of heavy metal activities.However, the released phosphorus could lower their activities by the combination with heavy metals.Heavy metal activities were changed by the two forces. The content of available phosphorus had no significant correlations with available heavy metals and possible reasons could be that two kinds of phosphorus tested affected heavy metals differently.Enzyme activity in the tailings substrates and microbial biomass were closely related with their chemical properties, but the biological properties still exist differences with the correlation of chemical properties. The pH and EC were the leading factors inhibiting enzyme activities. Results suggested that urease and alkaline phosphatase significantly correlated with pH, but dehydrogenase, urease, alkaline phosphatase, available nitrogen and available potassium were negatively related to conductivity. Heavy metals affected enzyme activities in the tailings substrates in different aspects.Pb and Zn inhibited alkaline phosphatase activity in the tailings, and Pb、Cr had negative correlation with urease, while As and Fe restricted catalase and dehydrogenase activities respectively.The combined reaction of nutrient amounts in the tailings and effective heavy metals led to physiological and ecological changes in Vicia faba. The photosynthetic index of Vicia faba was higher than the group without phosphorus in the early growth stage for the abundant nutrients. Photosynthesis in aboveground parts of the plants, was inhibited in late period for the accumulation of high concentrations of heavy metals which were absorbed together with nutrients. It was concluded that both RP group and Aureobasidium pullulans treatment could increase root biomass and phosphorus contents and the co-reaction of both substances had better effects.This experiment was limited to the research of effective heavy metal contents in the tailings, heavy metal contents in the plants and photosynthesis. Further research of the relations between heavy metal contents in the plants under different growth stages and photosynthesis was to be done to determine injury mechanisms of heavy metals towards photosynthesis in the plants during the processes of tailings restoration. |
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