Study On Temporal And Spatial Variation Of CO₂ Concentration In Open-Pit Mining Area

China is a big mining country.Mineral resources provide energy needs for the rapid development of society,but at the same time destroy the land in the mining area,seriously affect the ecological environment of the mining area,and the carbon balance of the mining area is threatened to a certain extent.In the process of developing and utilizing mineral resources in open-pit mining areas,a large amount of CO₂ gas will be produced.Research on the temporal and spatial changes of CO₂ concentration in open-pit mining activities can provide certain help and decision-making assistance.This paper selects the Qinggangshu limestone mining area in Yunlin Village,Tongquan Town,Beichuan County,Mianyang City,Sichuan Province as the research area,collects CO₂ concentration data from January to December in 2022,and conducts comparative analysis with carbon satellite data to summarize the temporal and spatial changes of CO₂concentration in the open-pit mining area feature.Analyze the changes in vegetation coverage and land cover in the open-pit mining area from January to December 2022,and explore the influence of vegetation coverage,land cover and terrain on the CO₂ concentration in the open-pit mining area in combination with topographical factors.Gas changes provide a certain theoretical basis.The paper mainly draws the following conclusions:（1）The CO₂ concentration in a single-day open-pit mining area is parabolic.From 0:00 to 5:00,the CO₂ concentration gradually increased;from 5:00 to 12.30,the CO₂ concentration began to decrease;from12.30 to 19.30,the CO₂ concentration tended to be stable;after 19.30,the CO₂ concentration rose slowly and continued until midnight of the next day.The daily CO₂ concentration is highest at 5:00 and lowest at14:30.In 2022,the monthly average CO₂ change trend in open-pit mining areas is increase-decrease-increase,increasing from January to April,decreasing from May to August,and increasing from September to December.The highest monthly average CO₂ concentration is in April 2022,and the lowest is in August2022.The sequence of CO₂ concentration in four seasons in the open-pit mining area is:spring CO₂concentration>winter CO₂ concentration>autumn CO₂ concentration>summer CO₂ concentration.（2）At the same height,the CO₂ concentration in the northwest of the study area is higher,the CO₂concentration in the middle is relatively stable,and the CO₂ concentration in the southeast is lower.The northwestern part of the study area is mainly an open-pit mining area,with relatively steep terrain and sparse vegetation around it.In contrast,the southeastern part of the study area is mainly the roads connecting the open-pit mining area to the surrounding areas and related buildings in the mining area.The terrain is relatively flat and the surrounding vegetation coverage is relatively high.At different altitudes,the higher the altitude,the lower the CO₂ concentration.The CO₂ concentration in the open-pit mining area is the highest when it is 100 meters from the ground,and the CO₂ concentration is the lowest when it is 350 meters from the ground.（3）From January to February 2022,the vegetation coverage in the study area decreased;from March to May,the vegetation coverage in the study area increased slowly;from June to September,the vegetation coverage in the study area continued to decline;from October to December In June,the vegetation coverage in the study area tended to be stable.In 2022,the mining area will continue to expand,with a slower growth rate from January to May,a faster growth rate from May to September,and a relatively stable growth rate from October to December.（4）The paper selects 6 influencing factors of vegetation coverage,land cover,slope,slope aspect,elevation and terrain relief,and explores the influence of the 6 factors on the CO₂ concentration in open-pit mining areas.The order of influence is elevation>slope>terrain relief degree>vegetation coverage>aspect>land cover.Different influencing factors have enhanced effects on the interactive operation of CO₂concentration in open-pit mining areas,among which the enhanced effects are relatively obvious:elevation-slope,elevation-topographic relief.The monthly average CO₂ concentration in Tongquan town is generally lower than that in the open-pit mining area.Considering that the two places are not far apart,and the natural conditions such as precipitation and temperature are basically the same,the main factor causing the difference in the monthly average CO₂ concentration between the two places is human activities,and the mining activities in the open-pit mining area are the most important part of it.