Study On The Changes In Land Ecological Quality Of Surface Mining Area Based On The Life Cycle Approach

The extraction and utilization of mineral resources has brought economic benefits as well as disturbance on the land ecological quality in mining area.This is a particular case to surface mining area.The land use in mining area has a significant feature of life cycle with a process of conversion,occupation and recovery.At present,the life cycle of mining enterprises has draw much academic attention,but there is a lack of research on the assessment of impact of mining on ecological quality and analysis of life cycle of land conversion,occupation and recovery in mining area.On the basis of life cycle theory,this dissertation systematically analyzes the process of land disturbance in the surface mining area,and then assesses the temporal and spatial change of land ecological quality and puts forward suggestions for the protection of ecological quality.This dissertation analyzd the spatiotemporal pattern of land use in the surface mining area.This dissertation aslo discussed the characteristics of land use in the three processes of life cyle including conversion,occupation and recovery.Based on the ecological service framework of the land ecosystem,the impact of land conversion,occupancy and recovery on the land ecological service was analyzed.With respect to the ecological function of the land in the surface mining area,this dissertation employed net primary productivity,carbon sequestration,water conservation and soil conservation as four indicators of the land ecological quality.Based on the gerneral method of life cycle assessment,this dissertation determined the overall framework,objectives,scope,as well as the spatiotemporal inventory and method of life cycle assessment of the land ecological quality impact in surface mining area.Baiyinhua coal mine in Inner Mongolia was employed as the case study area,the spatial pattern and dynamic change of land use in Baiyinhua mining area were detected by using five remote imageries from 1995 to 2015 and other data such as land reclamation plan and geological environment monitoring.The dissertation analyzd the land ecological quality during different life cycle process including coversion,occupation and recovery,and also assessed the impact of mining on the land ecological quality by using the established method based one life cycle theory.The results show that the original landform was reduced by 55.82 km² from 1995 to2015.To the end of 2015,the area of the open pit was 22.83 km²,accounting for8.55%of the total area.The area of dump was 24.57 km²,accounting for 9.2%of the total mining area.The area of reclaimed land was 1.41 km²,accounting for 0.53%of the total area.The cumulative impact of mining on NPP,carbon sequestration,water conservation and soil retention in the whole mining area from 1995 to 2015 were 6.48×10¹⁰ g,2.92×10¹⁰ g,2.96×10¹⁰ g,4.44×10¹⁰ g respectively.The impact of material quality for the four indicators were 242.80 g,109.28 g,110.73 g,166.25 g per square meter respectively.For the reclaimed area that has experienced full life cycle of land use,the four ecological quality indicators had decreased 0.80×10⁸ g,0.36×10⁸ g,0.38×10⁸ g,0.63×10⁸ g?for total reclaimed area?and reduced by56.90 g,25.60 g,26.60 g,44.81 g?for single square meter?from 1995 to 2015.On the basis of the change pattern of land ecological quality in surface mining area,the trend of land ecological quality and the role of land reclamation in restoring the land ecological quality were analyzed.A few suggestions about the rational development of mineral resources and the strengthening of land protection and management were proposed.