酸性矿山排水泄漏对荒漠草原土壤剖面细菌群落的影响

Effects of Acid Mine Drainage Leakage on Bacterial Communities in Desert Grassland Soil Profiles

酸性矿山排水(AMD)因其安全隐患和环境风险而备受关注.然而,人们对于AMD泄漏对生态环境脆弱的荒漠草原土壤理化性质和细菌群落的影响知之甚少,尤其在土壤剖面上.因此,分别以AMD污染剖面和清洁剖面为研究对象,探究AMD对荒漠草原不同深度土层土壤理化性质和细菌群落组成、结构和相互作用的影响,并在此基础上分析细菌群落变化的驱动因素.结果表明,AMD会显著降低剖面上层(0~40 cm)土壤的pH值,并提高电导率(EC)和重金属含量;AMD污染剖面细菌以变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)和放线菌门(Actinobacterota)为主,而在清洁剖面细菌以厚壁菌门(Firmicutes)和类杆菌门(Bacteroidota)为主,其中Thermithiobacillus和Alloprevotella分别是污染剖面和清洁剖面的生物标识;AMD污染会显著降低剖面上层土壤的细菌多样性,并显著改变细菌群落结构.冗余分析结果表明,土壤理化性质解释了细菌群落变化57.21%的变异,其中EC、TP、TN、As、Zn和Pb是细菌群落变化的主要驱动因素.网络分析表明,AMD污染增加了剖面的复杂性、模块性和群落内部的竞争,从而提高细菌群落的稳定和适应性.总之,研究提供了AMD污染对荒漠草原土壤理化性质和细菌群落影响的有用信息,这可能有助于提高极端生境下AMD污染对土壤生态环境危害的认识.

Acid mine drainage(AMD)is of great concern owing to its safety hazards and environmental risks.However,little is known about the effects of AMD leakage on soil physicochemical properties and bacterial communities in ecologically fragile desert steppe soils,especially in the soil profile.Therefore,an AMD-contaminated profile and clean profile were used as research objects respectively to investigate the effects of AMD on soil physicochemical properties and bacterial community composition,structure,and interactions in soil layers at different depths of desert grassland and,based on this,to analyze the driving factors of bacterial community changes.The results showed that AMD significantly decreased the pH and increased electrical conductivity(EC)and heavy metal content in the upper(0-40 cm)soil layer of the profile.The AMD-contaminated profile bacteria were dominated by Proteobacteria,Firmicutes,and Actinobacterota,whereas clean profile bacteria were dominated by Firmicutes and Bacteroidota,with Thermithiobacillus and Alloprevotella being the biomarkers for the contaminated and clean profiles,respectively.AMD contamination significantly reduced bacterial diversity and significantly altered bacterial community structure in the upper soil layers of the profile.The results of redundancy analysis showed that soil physicochemical properties explained 57.21%of the variation in bacterial community changes,with EC,TP,TN,As,Zn,and Pb being the main drivers of bacterial community changes.Network analyses showed that AMD contamination increased profile complexity,modularity,and intra-community competition,thereby improving bacterial community stability and resilience.In conclusion,the study provided useful information on the effects of AMD pollution on soil physicochemical properties and bacterial communities in desert steppe soils,which may help to improve the understanding of the ecological hazards of AMD pollution on soils in extreme habitats.