The Mechanism Research Of Artificially Constructed Bamboo-Willow (Salic SP.)-Paspalum Scrobiculatum Linn-Macleaya Cordata Community Plots To Enhance The Remediation Of Uranium Contaminated Soil

Uranium mining and smelting activities have resulted in the contamination of soils in the environment.In the process of uranium mining,a large number of pollutants containing uranium will be produced,such as waste rocks,tailings and effluent.With the passage of time and various unpredictable natural and man-made factors,The uranium of waste rocks,tailings and effluent may migrate to the soil circle along with various hydrogeological movements.Uranium in contaminated soils not only degrades soil fertility,reduces crop yields and quality,but also deteriorates water environment,and enters the food chain,which will pose serious threats to human health.Phytoremediation has become quite attractive in the remediation of uranium contaminated soils due to its environmental friendliness,low cost and sustainable development and widespread application.The characteristics of tolerance,uptake and accumulation of uranium vary greatly among different plants,and the plant community plot has obvious advantages over a single plant population.Bamboo-willow(Salix sp.)is a woody plant with fast growth,high biomass and strong adaptability,and it can be used as a potential remediating material for heavy metal contaminated soils.Paspalumscrobiculatum linn is a perennial herb of Gramineae,which has strong tolerance to heavy metals.Macleaya cordata is a perennial herb of the Papaveraceae,and has high accumulation capability for uranium.In this study,they were used to artificially construct plant community plots,and greenhouse experiments were conducted to study the enhanced phytoremediation of uranium contaminated soils by these plant community plots.The objective of this research was to develop an artificially constructed plant community plots for the enhanced phytoremediation of uranium contaminated soil and its mechanism.It was found that their remediation efficiencies were in the order Bamboo-willow(Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata > Bamboo-willow(Salix sp.)-Macleaya cordata > Paspalum scrobiculatum linn-Macleaya cordata > Bamboo-willow(Salix sp.)-Paspalum scrobiculatum linn.The bioaccumulation amount of uranium by each plant in the Bamboo-willow(Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata community plot was significantly(P<0.05)higher than that by its single population,the bioaccumulation amounts of uranium by Bamboo-willow(Salix sp.),Paspalum scrobiculatum linn and Macleaya cordata were 0.29,0.32 and 2.19mg/plant,respectively,and they were increased by 31.82%,77.78% and146.07%,respectively,and the transfer efficiencies by the plants were increased by 150%,110% and 52.17%,respectively.Acidobateria and Ascomycota were found to be abundant in the rhizosphere soil of the Bamboo-willow(Salix sp.)-Paspalum scrobiculatum linn-Macleaya cordata community plot.The interaction between the plant roots and the microorganisms led to the high content of organic acids such as oxalic acid in the rhizosphere soil of the plant community plot,which was significantly(P< 0.05)higher than that of its single population.The chelation of the organic acids with uraniumresulted in an increase in the proportion of exchangeable uranium in soil.Furthermore,burkholderia,which is an iron-producing carrier bacteria and can increase the uptake and accumulation of uranium by plants,Nematoda,which can improve soil quality by improving soil enzyme activity,and Leptolyngbya,which is a plant growth promoting rhizobacteria and can increase the biomass of plants,emerged in the rhizosphere soil of the plant community plot.These may be the mechanisms by which the phytoremediation of the uranium contaminated soils was enhanced by the plant community plot.