The Characteristics Of Microbial Community In Serpentine Mining Area And Its Carbon Sequestration Potential

Soil nutrient and mineral composition affect the composition and succession of microbial community structure,and microbial life activities will also have important effects on soil mineral weathering,secondary mineral formation and nutrient cycling.Exploring the microbial community structure characteristics of the serpentine mining area and analyzing its carbon sequestration potential is of great significance for the use of serpentine carbonation to capture atmospheric CO₂.In this study,the serpentine mine in Donghai County,Jiangsu Province was used as the research object,and the high-throughput sequencing technology was used to analyze the microbial diversity of the exposed rock surface and the serpentine?including bare rock?surface soil under different vegetation cover.Combined with the analysis of rock and soil samples by X-Ray Diffractometer?XRD?,X-ray Fluorescence Spectrometer?XRF?,Field Emission Scanning Electron Microscope?FESEM?and Energy Dispersive Spectrometer?EDS?,exploring the microbial community structure in serpentine mining areas and its role in weathering of serpentine.The research results show that Proteobacteria,Chloroflexi,and Actinobacteria occupy a large proportion on the surface of exposed serpentine and the soil of serpentine,and are stable and dominant populations.Cyanobacteria has higher abundance in the bare rock surface,algae crust and the rhizosphere of bryophytes,but significantly reduced in the rhizosphere of gramineae,which shows a change in the role of bacteria in serpentine soil environments with different degrees of weathering.In the rhizosphere of bryophytes,Chloroflexi becomes the phylum with the largest proportion,and the abundance of Actinobacteria in the rhizospheric soil of gramineae increased sharply,becoming the dominant group.The bacterial community structure in the xylophyta rhizosphere is similar to that in the gramineous plant rhizosphere.Ascomycota occupies a certain proportion in all sampled samples,but it has an absolute advantage in the rhizosphere of gramineous plants.At the genus level,fungi with the ability to degrade cellulose,such as Penicillium and Fusarium,dominate in each group of samples in the serpentine area,which may be related to their degradation and utilization of biomacromolecule organic matter.The fungal community structure in the xylophyta rhizosphere and the serpentine soil is obviously different.Combined with the results of the difference in the microbial community,the presence of serpentine in the soil may have a screening or enrichment effect on microorganisms of certain genera.Based on the mineral analysis results of serpentine samples collected under different vegetation coverage in the mining area,it was found that serpentine on the surface of the exposed serpentine and under the algal crust contains calcite and high-magnesium calcite,while the serpentine soil in the rhizosphere of bryophytes and gramineous plants contains only high-magnesium calcite.It is speculated that the weathering of serpentine by microorganisms and plants makes the soil environment contain a large amount of magnesium ions,which is more likely to lead to the formation of high-magnesium calcite.Collecting multiple soil samples within 50 km of the mining area and its surroundings,it was found that high-magnesium calcite only appears in the mine soil containing serpentine,the further away from the mining area,the harder it is to find High-magnesium calcite,and this result provides a new idea for the carbon fixation by the way of biological weathering of serpentine to form high-magnesium calcite.In order to further explore the ability of serpentine to couple carbonate formation when weathering,a pot experiment was carried out to add serpentine to the soil for plant cultivation.The results show that adding serpentine to the soil to grow plants can promote the growth of plants and increase the biomass.At the same time,it will increase the soil p H and increase the formation of soil carbonate.Due to the limitation of the test time of potted plants,the small amount of carbonate mixture formed in the soil is difficult to be separated,and it is difficult to be detected in the analysis of mineral composition.In general,from bare rock to serpentine surface covered with lichen,algae,grass,etc.,the more complex the plant group,the more significant the increase in bacterial species,the community species richness and uniformity also increased,but the fungal species,species richness and uniformity decreased overall.With the increase in the degree of rock weathering and the colonization of plants,soil and plants seem to be able to jointly from a relatively stable biological community structure suitable for the environment of the serpentine mining area,drive the weathering of surface serpentine and the formation of calcite and high-magnesium calcite.This study initially revealed the structural characteristics of the microbial community during the weathering of serpentine and the potential ecological function of the addition of serpentine to the soil,providing a theoretical basis for the use of serpentine weathering under natural conditions to capture atmospheric CO₂.