Research On The Influence Of Soil And Vegetation Around Metal Mining In Desert Grassland

Taking a gold mine in Sunite Right county of Xilin Gol as the research object,from two aspects of soil and vegetation to explore the effect of mining area development and construction activities,the influence of the determination of soil physical and chemical properties,and four kinds of heavy metal element contents in soil,and use a variety of evaluation methods of soil heavy metal accumulation in ecological risk assessment,Soil quality was evaluated from two aspects: main physical and chemical properties of soil and heavy metal content.Based on NDVI index,the dynamic change of vegetation coverage in different development stages was analyzed.Finally,remote sensing ecological index method was used to evaluate the ecological quality.The main conclusions are as follows:(1)The area of 5km around the gold mining was determined as the ecological sensitive area,the mining area and the ecological sensitive area were taken as the research area,and the control group was set 8km outside the mining area.The analysis results of soil physical and chemical properties and heavy metals showed that:The contents of AP,soc and AN in the soil increased with the distance from the mining area.The average soil water content and p H in the study area were lower than those in the control group.Compared with the soil environmental background values in Inner Mongolia,the over-standard rate of heavy metals in the four soils in the study area was As(90%)> Cu(88%)> Hg(79%)> Cd(76%).Compared with the national standard,only 6% of As exceeded the standard.The regional comprehensive ecological risk assessment results are as follows: south of RI tailings pond(127.35)>North of RI tailings pond(118.18)> RI dump(96.26).The comprehensive evaluation results of soil quality were as follows: the soil quality around the dump and in the south of the study area fluctuated within 3km,and the soil quality in the north of the study area changed significantly within 1km.(2)Based on the study of spatio-temporal dynamic changes of NDVI in the study area in the whole development stage of the mining area,it is found that the damage to vegetation is the most serious during the construction period of gold mine(2009-2011),which decreases from 0.3351 to 0.0083.In 2016,the NDVI value reached 0.2382 in the whole development stage.With the extension of the development and utilization time of mineral resources,the vegetation normalized index showed a rising trend.(3)The gold production and construction process is divided into three development stages: construction period(2009-2011),production period(2011-2016),and stable production period(2016-2021).The ecological quality changes in different stages are compared and analyzed.The results show that: On the time scale,the ecological quality of the study area from 2009 to 2021 showed a constant change law,and the ecological quality of the study area was mainly unchanged or slightly improved during the construction period.In the production period,ecological quality was mainly improved significantly,and reached the optimal level in 2016.Although the ecological quality in stable yield period decreased,it was still better than that in construction period.At the spatial scale,the ecological quality in the north of the study area was better than that in the south.