The Seasonal Dynamics Of Soil Bacterial Community Structure And Function In A REEs Tailings Pond

The soil microorganism was an indispensable part of soil environment and was very important to the whole soil ecosystem.However,with the increasing demand for rare earth elements,the large amount of waste from the mining and refining of rare earth ores posed a serious threat to the soil environment.At present,there was a lack of research on soil microbial community structure and potential function in rare earth tailings reservoir area.Therefore,this study took the soil around a rare earth tailings pond as the research object.Surface soil samples were collected in winter and summe.Taking soil microorganisms as the entry point,the seasonal variation rules of structure and function of soil bacteria community were explored by combining high-throughput sequencing technology with Tax4 Fun function prediction.The main conclusions are as follows:(1)Seasonal variation had a significant effect on soil physical and chemical properties.In summer,soil pH,K content,Ca content,Mg content and organic matter content increased,while water content,total nitrogen and total phosphorus content decreased.The content of rare earth elements in soil increased with the development of mining activities,and the environmental risks brought by rare earth elements were increasing.The content of rare earth elements in soil ranges from 222.31 mg/kg to 9238.56 mg/kg in winter,and from275.75 mg/kg to 27220.16 mg/kg in summer.(2)Seasonal variation had no significant effect on the composition of dominant specie and the diversity and abundance of soil bacterial community increased in summer.The accumulation of rare earth elements inhibited the diversity and abundance of bacterial communities.The three dominant species were Proteobacteria,Actinobacteria and Chloroflexi.It accounts for more than 55% of the relative abundance of bacterial community.Halomonas and Truepera could adapt to the arid and salty soil environment in north China and had high abundance under the severe rare earth elements accumulation level.The discovery of Halomonas and Truepera provided a reference for the remediation of contaminated soil in rare earth mining areas.(3)A total of 277 functional pathways were found in all the samples.The functional pathways of metabolism were dominant and account for more than 60% of all functions.The increase of soil temperature in summer increased the metabolic capacity of soilbacterial community.The decrease of energy metabolism and amino acid metabolism in SC samples in summer was related to the accumulation of rare earth elements,which could promote the metabolism of carbohydrates.