Ecological Improvement Of Soil In Dump Of Closed Open-cast Coal Mine In Severe Cold Region

As the main mining method in the world,open-pit mining gradually accounts for15% of the total coal production in China.However,in the process of open-pit coal mining,a large amount of land and ecological resources will be destroyed and occupied.Compared to undamaged topsoil,the proportion of rock debris in waste dump soil is high,the accumulation density is high,the soil is sensitive to erosion,has strong alkalinity,and lacks nutrients,leading to soil erosion,vegetation loss,desertification,and adverse impacts on geology,hydrology,and regional climate.Due to its low temperature,low precipitation,and short plant growth period,the difficulty of restoration in high and cold regions has been exacerbated.Therefore,carrying out research on ecological monitoring and ecological restoration of coal mines in alpine regions plays an important role in reconstructing the ecosystem of alpine mining areas.This article aims at Lingquan Closed Pit Open Pit Coal Mine in Inner Mongolia,through a combination of field investigation and indoor experiments,to investigate the soil properties of Lingquan Open Pit Coal Mine,classify different soils,and implement different improvement methods to improve the soil,and evaluate the improvement methods of the soil from its physical,chemical,microbial,and soil organic carbon properties.To master the soil properties of the Lingquan open-pit closed pit coal mine,propose a combined chemical,microbial,and plant remediation approach to improve the soil in the waste dump,and explore the changes in soil organic carbon properties during the ecological remediation process.The main research conclusions are as follows:(1)The overall soil of Lingquan Coal Mine is neutral to slightly alkaline.The average values of organic matter,total nitrogen,alkali hydrolyzed nitrogen,and available phosphorus were at a relatively deficient level;Total phosphorus is at a deficient level;Total potassium and available potassium are at the medium level.The overall soil fertility is at a low level and has a large degree of dispersion.The plant diversity index in the mine pit is the highest.With the improvement of fertility,the proportion of plants such as Leguminosae and Cyperaceae gradually increases,while the proportion of Chenopodiaceae and Gramineae decreases,and the proportion of perennial plants in areas with higher fertility is greater.(2)Under different improvement methods,soil nutrient indicators have greatly improved.The highest content of organic matter was found under high levels of organic fertilizer and biochar.Soil nutrients increase with the increase in the amount of organic fertilizer applied,but studies have found that high concentrations of biochar have an inhibitory effect on the release of available nutrients.The change of aggregate is mainly reflected in the early stage of plant growth,and the proportion of aggregate in soil varies under different treatments and periods.After adding modifiers,the content of large particle size aggregates in soil increased,and the MWD increased.(3)Modifiers can improve the richness,evenness,and diversity of soil microbial communities.Under different improvement measures,actinomycetes are the most abundant bacterial phylum,followed by proteus.There is a certain change in the alpha index of fungi.Soil improvement can effectively improve the richness of soil fungi,but the richness and diversity of soil fungi will decrease after application of modifiers.Under different measures,ascomycetes are the most abundant fungal phylum among them.Redundancy analysis of soil physical and chemical indicators and enzyme activity showed that SOC,AN,and 0.25～0.053 mm aggregates were significant influencing factors for soil enzyme activity.The correlation between alfalfa germination rate and soil improvement measures is poor.The proportion of modifiers mainly affects the height of alfalfa at the early growth stage,but has a relatively small impact on the late growth stage of alfalfa.Each improvement measure has a significant promoting effect on alfalfa biomass,and its change trend has a strong correlation with the changes in soil available nutrients.(4)Principal component analysis was conducted on soil nutrients,soil MWD,soil enzyme activity,plant height and dry weight of plants,and soil quality index S was calculated.The results showed that L9 had the best effect.When selecting soil improvement measures,factors such as long-term effectiveness and economic efficiency should be comprehensively considered to select the most suitable mix plan.(5)Infrared spectrum analysis of the improver and soil showed that the organic carbon in biochar was more stable than that in organic fertilizer.The proportion of polysaccharides in the improved soil decreased significantly,while the proportion of amide carbon and aromatic carbon gradually increased.The content of organic carbon in soil aggregates in each treatment increased with the decrease in particle size of the aggregates.With the increase in the amount of modifier applied,the contribution rate of soil organic carbon for 2mm and 0.25～0.053 mm aggregates in soil gradually increased,while the contribution rate of soil organic carbon for<0.053 mm aggregates gradually decreased< The retention ratio of aromatic carbon and amide carbon in 0.053 mm aggregates is large,while the content of fatty carbon in 0.25～0.053 mm aggregates is the highest.Under different improvement measures,the content of EOC,DOC,and MBC in soil increased,and the carbon pool index increased,but the carbon pool activity index decreased.There is a strong correlation between soil bacterial and fungal communities and the properties of soil organic carbon.The relative abundance of nutrient rich microorganisms in soil with high exogenous carbon content was higher,while the relative abundance of nutrient poor microorganisms in unmodified soil was higher than that in improved soil.The thesis includes 43 diagrams,25 tables,and 101 references...