| Soil carbon pool research has always been the hot topic in the academics. It has agreat impact on soil quantity and atmospheric greenhouse gases concentration. In coalmining area, coal extraction caused land use change. However, the responds of soilcarbon pool to this change are not clear. So, it became another important researchfield in the study of subsiding land and reclamation soil in coal mining area.In the high groundwater level plain of east China, a full investigation ofsubsiding land and reclamation soil in coal mining area has been conducted.Thereclamation area of coal-mining subsidence in Liuxin town Tongshan county andXuzhou city was taken as a typical case. The characteristics of change and content ofthe reclaimed soil organic carbon and inorganic carbon under different reclamationmethods and land use patterns were analyzed systematically by field investigation andlaboratory test of soil samples. The principal component analysis (PCA) method hasbeen used to analyze the principal component affecting the quality of soil carbon poolin the study area, and the causality of reclamation methods and land use patternsaffecting the carbon pool of reclaimed soil.The findings not only enriched and optimized the research fields of soil carbonpool, but also provided references for the choice of the ways of reclamation and landuse in subsiding land in the high groundwater level coal mining area.The main work and contributions of this dissertation include:Firstly, Analyzing systematically the differences of the composition andcomponent of soil carbon pool between the soil in coal-mining area and natural soil,this dissertation suggested that soil organic carbon pool may be divided into unstableorganic carbon pool and relatively stable organic carbon pool, and that coal carbon isalso contained in the reclamation soil of coal-mining subsidence in addition to thegeneral content of all kinds of carbon in natural soil, and that coal-carbon should beclassified as relatively stable organic carbon pool and, further, this dissertationanalyzed the origin and distribution of coal carbon in the soil in coal-mining area. Andthe soil inorganic carbon pools were divided into unstable inorganic carbon pool andrelatively stable inorganic carbon pool similar to soil organic carbon pools. Next, thesensitivity of the carbon pools and relationships between the various types of carbonpools in reclamation soil in coal-mining area were discussed.Secondly, the laws of the change of reclamation soil carbon pool were made clear and, further, this dissertation analyzed the role of various types of carbon in theprocess of carbon pool recovery in reclaimed soil.The characteristics were studied detail which is the change of total carbon pooldensity(pTC), total inorganic carbon pool density(pTIC), total organic carbon pooldensity(pTOC) and content of all types of carbon in the reclamation soil withtime-varying after land reclamation by mixing level method and with usage of ricewheat rotation, and the models were constructed to estimate how long the soil carbondensity and content will reach a maximum value after land reclamation of thecoal-mining subsidence. This dissertation also discussed the recovery effect of soilcarbon pool density and soil carbon content after land reclamation of coal-miningsubsidence and the carbon sequestration potential of reclamation soil.Thirdly, a comprehensive study was done about the effect of differentreclamation methods and land usages on soil carbon pool.This dissertation studied the effect of different reclamation methods(i.e. mixinglevel reclamation(MLR), gangue filling reclamation(GFR), mud pumpreclamation(MPR), fly-ash filling reclamation(FFR) under same usage of rice-wheatrotation) and different land usages(i.e. rice-wheat rotation usage(RW), cotton-beanrotation usage(CB) and tree plantation(TREE) on land by method of mixing levelreclamation) on soil carbon pool by analyzing the difference of pTC, pTIC, pTOCandcontents of various types of carbon. And the causality of different reclamationmethods and land usages affecting the carbon pool of reclamation soil was discussedinternally and externally from various properties of the reclamation soils (i.e. carbonpool component and composition, soil particle composition, fractal dimension,aggregate structure and associated properties, compaction, porosity, water content,specific gravity, etc.,).Fourthly, suggestions of land reclamation and use in coal-mining areaBased on the characteristics which Tongshan mining area in Xuzhou city belongsto the plain of high groundwater levels, according to the research results about theeffect of land reclamation and use of subsidence on the composition and change ofsoil carbon pools in the study area, a overall proposal was made on land reclamationand utilization that is “Land rehabilitation programs and use patterns should bedesigned according to local conditions and the principles of ecology, so that thesecondary serious damage to ecosystem and carbon loss of ecosystem during theprocess of land reclamation can be mitigated effectively.”... |
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