Study On Dynamic Changes Of Soil Properties Of Reclaimed Land Of Open-pit Coal Mine In Steppe Area

With the development of the mining area,large-scale grasslands have been occupied by dumping sites,thus giving rise to a series of conflicts among the environment,resources,and humanities,and having bad impacts on the environment and the society.Only mining while restoring can maintain the sustainable development of the mining area for a long time.It is essential to restore dump.The way that engineering combined with plant reclamation measures is used widely in reclamation,but it is not work well.In this paper,the dynamic characteristics of soil properties including soil quality,soil enzyme activity and heavy metal content were compared in the dump under different reclamation years,in order to explore influence of soil properties to environmental changes and the interaction between soil properties and the response.The major findings are listed as follows:1)Mining and dumping methods reduces soil fertility and increases soil alkalinity,resulting in poor soil quality;soil fertility is still on the decline in the early recultivation,and soil quality has improved with the reclamation processing.However,the soil fertility has not back to the original level.Only through the methods that sand barriers combined with planting to reclaim,the result of damaged ecosystem reconstruction is not very satisfactory,and reclamation up to 10 years still does not solve the weak environmental problems caused by mining,and lead to lower productivity.With the reclamation processing,the content of heavy metals in soil gradually recovered to the initial level.Except for iron,the content of heavy metals in soil which reclaimed for 10 years was not different from that in the control group significantly.2)Correlation analyses showed that there was a significant negative correlation between soil carbon-nitrogen ratio,pH and soil organic matter;and there was a significant positive correlation between soil total nitrogen and soil carbon-nitrogen ratio.Soil physical and chemical properties and heavy metal content are closely related;there was a significant negative correlation between soil pH and arsenic content in soil;the sand content was significantly negative correlation with soil iron,chromium,manganese elements,but the silt is conversely.3)With the reclamation processing,the structural composition and dynamic distribution of soil bacterial community haven't changed significantly,but its richness has changed significantly,indicated that bacterial communities are more sensitive to environmental changes.With the reclamation processing,the structural composition,richness,and dynamic distribution of soil fungal communities have changed significantly.That is,changes in soil environment have a more profound effect on soil fungal communities,indicating that soil fungi are more sensitive to the environment than soil bacteria.4)Correlation analyses showed that there was a significant positive correlation between soil microorganisms and available soil nutrients during reclamation;the soil bacterial communities was significantly positive correlation with soil available phosphorus and soil invertase activity;the soil fungal communities also was significantly positive correlation with soil available nitrogen,but the soil fungal community and soil bacterial community at the later reclamation years was significantly negative correlation with soil pH value,soil electrical conductivity.The soil pH value was significantly negatively correlated with.SCG.and TK10.The soil available phosphorus was significantly positive correlation with Lecanoromycetes.The available nitrogen was significantly positive correlation with Actinobacteria,Sordariomycetes,Tremellomycetes,Ustilaginomycetes,Laboulbeniomycetes.