Phytoremediation of Uranium Contaminated Soil by Macleaya cordata and Salicaceae in Intercropping Pattern

The uranium accumulators including Helianthus annuus, Macleaya cordata and Salicaceae were planted in monoculture and intercropping patterns to remediate uranium contaminated soils. The bioaccumulation capabilities of the plants for uranium, and the microbial communities, the organic acid contents and the transformation of uranium species in their rhizosphere soils were investigated. It is found that compared with the monoculture pattern, the bioaccumulation amounts of uranium by Macleaya cordata and Salicaceae in the intercropping pattern increase by 183.50% and 24.93%, respectively, and their translocation factors increase by 120.31% and 104.3%, respectively, showing that the phytoremediation of uranium by Macleaya cordata and Salicaceae in intercropping pattern has the highest efficiency, and the proportions of tolerant bacteria Acidobacteria, growth-promoting bacteria Bradyrhizobium and excreting organic acids bacteria Aspergillus significantly increase, and the contents of oxalic acid and malonic acid also obviously increase. Macleaya cordata and Salicaceae in intercropping pattern could remediate uranium contaminated soils more efficiently than in monoculture pattern, the main mechanism may be that the Acidobacteria and Bradyrhizobium improve their tolerance and bioaccumulation abilities for uranium, and the organic acids excreted by Aspergillus could chelate with uranium, resulting in the increase of the proportion of uranium in exchangeable fraction.