Study On Ecological Environmental Effect Of Coal Mine Closure

The footprint of human activity is almost in every corner of the globe. Due to the interference of human activities tend to produce a series of ecological environment problem, more attention is paid to the ecological environment effect in some specific areas. In the human engineering activity, mineral development disturbance to earth surface system is very severe. Mining disturbance is more complex than open pit mining. The ecological environment in coal mining area has become a hot research topic and the eco-environmental effect of coal mine closure has grandually been paid much attention too. To choose typical coal mine closure area to study the eco-environmental effect of coal mine closure not only can provide data support for mining activities in production mining area but also can provide effective decision-making basis for resource management and ecological environment protection in coal mine closure area.In this paper, two typical coal mine closure areas Taozao and Guanqiao are chosen as an example, which are in Zaozhuang coal mine area. Through literature review, field investigation, experimental analysis, remote sensing information extraction and comparative analysis, water environmental effect, soil environmental effect and the of the landscape pattern of land use change effect of coal mine closure are studied. Based on this, evaluation index system of intensity of ecological environmental effect of coal mine closure is built using PSR model. Intensity of ecological environmental effect of coal mine closure in Taozao coal field and Guanqiao coal field. Furthermore, scenario analysis of intensity of ecological environmental effect of coal mine closure in Tengzhou coal mine area is taken. The main study conclusions are as follows:(1) Analysis of water environmental effect of coal mine closure This study includes the analysis of groundwater environmental effect and surface water environmental effect. The main study results are as follows:(1) Coal gangue leaching experiment is taken selection gangue with different draining years and different stopping discharging years, results show: Hazardous substances are leached out of different kinds of gangue with different draining years and different stopping discharging years and the gangue under the surface(0-30cm) has longer time leached to stable p H than that under the surface(30-60cm) because the gangue under the surface(0-30cm) has higher degree of weathering; Coal gangue from leaching time > coal mine production has stopped the gangue leaching time; the longer the dumping years, leaching time is shorter, and less to stop dumping years and closed pit life;the leaching time < vegetation surface without vegetation of coal gangue; SO42-、total hardness、TDS、COD、Pb、Hg、Cd、Cr6+、Cu、Zn、Mn in leachate are all tending to be stable, in the initial leaching precipitation is high, after a concussion drop, the precipitation amount of SO42- is highest than others, is the main influencing factor of coal gangue to the surrounding ecological environment.(2) Select the Zaozhuang coal mine south gangue and Laicun coal gangue, Zaozhuang south coal gangue and Zouwu coal gangue as comparative study of surface water and shallow groundwater, results show: Effect of coal gangue on the surface water presented coal gangue dumps as the center outward diminishing. Influence radius of SO42->TDS、COD、Pb、Hg、Cd、Cr6+、Cu、Zn、Mn. Surface water influence radius of Zaozhuang coal gangue and Laicun coal gangue is about 500 m.The influence radius of shallow groundwater of south Zaozhuang coal gangue in the direction of groundwater flow is about 500 m, Zouwu coal gangue is about 300 m.(3) Comparative analysis of surface water in the coal mine area, results show: Effect of drainage on surface water environment quality in coal mine after closed, the closed period is the main factors of SO42-, mineralization degree, hardness variation in pond water; Influence of mine drainage on surface water has obvious effect of spatial scale, large spatial scale effect > medium spatial scale effect > small spatial scale effect.(4) Basin water chemical elements(SO42-) and hydrogen oxygen stable isotope tracer studies, research conclusion: The effects of mine drainage leakage recharge weakened after closed, however, with the continuous development of the mine water filling, there is a serious pollution in the series; After the pit is closed, the hydraulic connection between shallow groundwater and deep groundwater is weakened; The influence of the closed pit on the solute is greater than the exchange rate of water body.(2) Analysis of soil environmental effect of coal mine closure, research contents contain soil environment effect under the different conditions of reclamation soil environment effect analysis and mine drainage irrigation condition analysis, main research results:(1) There are differences at physical-chemical properties, heavy metal content and comprehensive quality in different types of land reclamation of subsidence(reclaimed land), coal gangue occupied land and industrial land reclamation. Though there are differences but there is no risk of heavy metal pollution. Comprehensive quality of reclaimed soil is of obvious difference. The differences have great relationship with fixed number of year of the coal mine pits, little more than differences with fixed number of year of the collapse, reclamation years and reclamation method.(2) The accumulation of gangue has influence on the surrounding soil at physical-chemical properties and heavy metal content,especially at SO42-. Its influence on the surrounding soil has no significant relationship with closure period, stopping dumping years. But there is a great correlation with the drainage period and the amount of coal gangue pile.(3) During the production of coal mine pit water irrigation quote, soil soluble salt content increased. After the pit closure, there is a trend of decrease, the content of soluble salt and water in mine have relationship with farm irrigation period; Soluble salt content in soil: Guanqiao coal field<Tengzhou coal field<Taozao coal field.(3) Change effect analysis of land use landscape pattern in coal mine closed pit, using remote sensing image data in different periods to extract land use landscape information, qualitative and quantitative analysis, the main results are as follows:(1) Period 1987-2011, land use landscape type composition of Taozao mining area and Guanqiao mining area change significant. The total area of agricultural land showed a continuous downward trend,2000 rose slightly, after that showed a clear downward trend; the overall area of construction land showed an increasing trend, area change is most obvious, but a slight decrease in 2000. The area of forest land, grassland and water body had little change. The change of agricultural land and construction land in 2000 has relationship to a large number of mine closed at the same time.(2) The conversion of agricultural land and construction land was maintained at a high level during the period of 1987-2011, all kinds of land use landscape have different degrees of conversion. The most significant is the transfer of agricultural land and construction land; A variety of land use landscape to maintain a high probability of transition, but the difference is significant; Grassland, forest land, water landscape transfer quantity is small, during a little change, mixed; The total land use landscape has a decreasing trend; The conversion of land use landscape is closely related to the exploitation of coal mine and the pits.(3) 1987-1994、1994-2000、2000-2006、2006-2011 four time periods of the comprehensive land use landscape dynamic index showed a decreasing trend, indicates that the intensity of land use landscape shifting is lower and tends to be stable.(4) 1987-2014 years, correlation analysis of the landscape pattern index and the statistical index of the closed pit coal mine in the mining area of the Taozhuang Basin show: Landscape pattern index based on type level, the patch density of the unused land and the statistical index of the closed pit coal mine closed the mine industrial site waste rate(%) was significantly related to the level 0.05. Landscape pattern index based on landscape level, the degree of fragmentation index and the average service life of the closed pit coal mine was significantly negative correlation with the level 0.05.(4) Study on the effect of ecological environment on closed pit in Zaozhuang coal mine According to the PSR concept model and the principle of index system construction, 22 indicators were constructed from three aspects of pressure, state and response, to form the evaluation index system of ecological environment effect intensity of closed pit in Zaozhuang coal mine, to evaluate the ecological environment effect intensity of closed pit in Zaozhuang coal mine by AHP. Evaluation result as follows:(1) Ecological environment effect intensity of closed pits in the coal mine of Taozao: EI=0.634, grade IV, strong impact.(2) Ecological environment effect intensity of closed pit in the coal mine of Guanqiao: EI=0.597, grade III, general impact.(3) Analysis on ecological environment effect of closed pit in Tengzhou mining area: Under the existing conditions of closed pit, EI=0.580, grade III, general impact; Evaluation results raise 10%, EI=0.638>0.6, grade IV, strong impact; Under ideal condition, EI=0.281, grade II, weaker effect; To increase the evaluation results by 10%, EI=0.308<0.6, still belong to a weaker influence range.