氮源添加对重金属污染土壤氨氧化微生物的影响OA北大核心CSTPCD

Mining activities lead to nutrient loss and land degradation in mining areas,where soil ecosystems are sensitive and fragile,making the restoration process complex and difficult.Among these limiting factors,nitrogen deficiency is a major obstacle to ecosystem recovery.To explore the mechanisms of nitrogen restoration in the soils of mining areas,this study focused on heavy metal-contaminated soils from the Siding Mining Area of Liuzhou,Guangxi.By conducting soil cultivation experiments and using high-throughput sequencing in combination with quantitative PCR technology,this study systematically investigated the effects of different application regimes of ammonium chloride(38.114 g∙m-1∙a-1(high concentration),9.54 g∙m-1∙a-1(low concentration)),and urea(21.43 g∙m-1∙a-1(high concentration),5.36 g∙m-1∙a-1(low concentration))with 12 times∙a-1(high abundance)and 2 times∙a-1(low abundance)added nitrogen on the abundance,diversity,and community composition of soil ammonia-oxidizing archaea(AOA)and ammonia-oxidizing bacteria(AOB).The results showed that the abundance of amoA-AOB gene was significantly higher than the abundance of amoA-AOA gene under different nitrogen application regimes,ranging from 1.56±0.01 to 3.58±0.03×107 copies·g-1(ammonium chloride)and 5.31±0.02 to 14.85±0.04×107 copies·g-1(urea).The average ACE,Shannon,and Simpson indices of the AOA community were 13.2,1.41,and 0.627 times higher,respectively,than those of the AOB community,suggesting that the α-diversity of AOA was more susceptible to different nitrogen treatments.The dominant phyla in AOA were Crenarchaeota,and Thaumarchaeota and the dominant genus was Nitrososphaera.For AOB,the dominant phylum was Proteobacteria and the dominant genera were Nitrospira and Nitrosovibrio.Correlation analysis showed that available phosphorus in the soil was a key factor affecting the abundance of amoA-AOB gene.Redundancy analysis showed that nitrogen in microbial biomass was the main factor causing changes in AOA community composition,whereas urease activity in the soil was the main factor affecting changes in AOB community composition.The addition of ammonium chloride and urea increased the potential ammonia oxidation and total nitrification potential of the soil by 1.15-to 3.03-fold and 2.15-to 8.55-fold,respectively,compared with the control,with AOB dominating the ammonia oxidation and nitrification processes in the soil.This study provides a theoretical basis for clarifying the patterns of changes in the nitrogen cycle in the soils of mining areas and rebuilding the soil nitrogen pool.