Influence Of Different Mining Damage Types On Soil Microorganisms And Enzyme Activities In The Coal Mines Of Northern Shaanxi

As a critical coal production base in the middle reaches of the Yellow River Basin,the mining damage pattern and mechanism of the soil environment in the coal mining area of northern Shaanxi has become a current research hotspot as a significant coal production base in the middle reaches of the Yellow River Basin.The thesis concentrates on the two main types of mining damage in northern Shaanxi Province coal mining areas,including subsidence and fracture,and uses the typical subsided loess slope(top,middle,and foot of the slope)and the soil around the fracture(fracture.width of 20-40 cm)as research objects.The spatial variation characteristics of soil microorganisms and enzymes have been analyzed under different types of mining damage.the influence of subsidence and fracture on soil microorganisms and enzymes was revealed.the main physicochemical control factors affecting the number of soil microorganisms and enzyme activities under different types of mining damage were screened.and the following main conclusions were formed:(1)On a typical sunken slope,with the transition of slope position,the numbers of soil bacteria,actinomycetes and fungi all showed that the foot of slope>top of slope>middle of slope.the numbers of bacteria,actinomycetes and fungi in the top,middle and foot of slope at any vertical depth were significantly different from the control group(P<0.05),especially the soil microorganisms in the middle of slope decreased the most,and the numbers of bacteria,actinomycetes and fungi decreased by 30%,42.37%and 39%respectively.In the area around the cracks of 20-40 cm in width,the closer the cracks,the greater the decrease in the number of bacteria,actinomycetes and fungi in the soil,especially in the soil microorganisms at a horizontal distance of 20 cm from the cracks and at a vertical depth of 60 cm or shallower,the average decrease in the number of bacteria,actinomycetes and fungi reached 34.56%,30%and 42.8%,respectively,When the horizontal distance exceeded 80cm,82cm and 97cm,respectively,the negative effect of cracks on the number of bacteria,actinomycetes and fungi in the surrounding soil basically disappeared.The effect of cracks on soil bacteria and fungi was greater than that of subsidence,and the effect of loess subsidence on actinomycetes was greater than that of crack area and wind-sand subsidence.(2)On a typical sunken slope,with the change of slope position,the activities of soil sucrase,urease,catalase and phosphatase all showed that the foot of slope>top of slope>middle of slope,and the content of soil catalase activity did not change significantly.the activities of sucrase,urease and phosphatase in the top,middle and foot of slope at any vertical depth were significantly different from the control group(P<0.05),and the differences of catalase activity were not significant(P>0.05).(P>0.05),but sucrase,urease and phosphatase activities in the soil in the middle of the slope decreased the most,by 30%,40%and 28%,respectively.around the cracks of 20-40 cm in width,the closer to the cracks,the greater the decrease of sucrase,urease,catalase and phosphatase activities in the soil,especially the horizontal distance of 20 cm from the cracks and the vertical depth of 60 cm shallow soil enzyme activities decreased the most,and sucrase,urease,catalase and phosphatase activities decreased the most.The average decrease of sucrase,urease,catalase and phosphatase activities reached 34.83%,58.13%,21.93%and 45.64%,respectively,and the negative effect of cracks on the activities of sucrase,urease,catalase and phosphatase in the surrounding soil basically disappeared when the horizontal distance exceeded 83cm,94cm,75 cm and 82cm,respectively.(3)The correlation analysis of physicochemical properties,microbial quantity and enzyme activity under different types of mining damage in coal mining areas in northern Shaanxi province shows that in coal mining subsidence areas,the main controlling factors affecting the characteristics of changes in soil microbial quantity are fast-acting nitrogen and fast-acting phosphorus,with correlation coefficients exceeding 0.6.the main controlling factors affecting the characteristics of changes in soil enzyme activity are organic matter,fast-acting nitrogen and fast-acting phosphorus,with correlation coefficients exceeding 0.7.In coal mining fracture areas,the main controlling factors affecting the characteristics of changes in soil microbial quantity are fast-acting nitrogen,fast-acting phosphorus and clay particles,with correlation coefficients exceeding 0.7.The main controlling factors affecting the characteristics of soil microbial population change were fast-acting N,fast-acting P and mucilage,with correlation coefficients over 0.7.the main controlling factors affecting the characteristics of soil enzyme activity change were fast-acting N,with correlation coefficients over 0.6.According to the results of gray correlation,it was found that:in the coal mining subsidence area,the main controlling factors affecting the characteristics of soil microbial population change were fast-acting N,with correlation degrees over 0.8.the main controlling factors affecting the characteristics of soil enzyme activity In the coal mining fracture zone,the main controlling factors affecting the change of soil microbial population were fast-acting N,fast-acting phosphorus and fast-acting potassium,with the correlation degree exceeding 0.7.the main controlling factor affecting the change of soil enzyme activity was fast-acting N,with a correlation degree exceeding 0.7.Therefore,fast-acting N could be the main controlling factor affecting soil microbial and enzyme activities in different mining damage.