新构土体土壤质量及水分与溶质运移研究

发布时间：2018-01-31 11:47

本文关键词： 土壤质量水分运动溶质运移砒砂岩新构土体晋陕蒙能源区　出处：《中国科学院研究生院(教育部水土保持与生态环境研究中心)》2016年博士论文　论文类型：学位论文

【摘要】：晋陕蒙能源区是我国重要的能源基地,煤炭开采带来经济效益的同时也对当地环境造成了极大的破坏,加之该地区属于干旱、半干旱的生态脆弱区,矿区土地复垦更是成为一种需要。为更好地认识煤矿开采对土壤质量的影响以及新构土体的水分与溶质运移规律,本文通过分析不同土地利用类型土壤剖面的土壤质量进行了评价,分析了植被恢复对土壤全氮及有机质含量的影响;分析不同土地利用类型土壤不同溶质运移特征及运移参数的影响因素;研究不同砒砂岩添加含量对风沙土溶质运移的影响以及砒砂岩添加厚度作为隔层对排土场土体溶质运移的影响,模拟了不同构型土体的混合、分层结构以及复垦土壤土石混合结构的入渗过程,主要得到以下结论:(1)与当地撂荒草地相比,由于煤矿开采,复垦排土场土壤质量出现不同程度的退化。主要表现为:土壤质地变粗,大多数属于砂质壤土;土壤容重变大,20-60 cm土层容重最大,60 cm以下土层容重降低;土壤p H升高,接近8.5;土壤CEC、有机质和全氮的含量低于撂荒草地;排土场与非排土场土壤的硝态氮、铵态氮、全磷、全钾含量分布无明显规律。与撂荒草地的比较,农地土壤质量有所提高。农地、东排土场刺槐林地、东排土场草地、北排土场草地、北排土场杨树林地的土壤退化指数分别为14.18%、-13.56%、-8.75%、-25.63%、-24.91%。(2)在排土场植被恢复选择中,与灌乔木植物相比,草本植物对土壤全氮和有机质含量的增加作用更强,尤其是沙打旺、苜蓿等豆科植物对土壤全氮和有机质的提高效果较好。杨树样地全氮和有机质含量均最低,说明杨树对土壤全氮含量的提高效果不好。表层0-10 cm土壤的全氮和有机质含量高于10-20 cm土层含量,说明植被恢复对0-10 cm土层改良效果更明显。随着复垦年限的增加,土壤全氮和有机质的含量也随之增加。(3)获得了不同土地利用类型以及不同深度土柱NO3--N和NH4+-N两种离子的运移特征,并使用模型对运移参数进行了模拟,得出了影响溶质运移的主要因素。表层(0-20 cm)土柱较深层土柱平均穿透时间较短,其他深度土柱穿透时间分布规律不明显。NH4+-N的穿透时间较NO3--N穿透时间延长,并且存在拖尾现象。平衡CDE模型对NO3--N运移过程较两区模型(T-R)拟合效果更好,不同土柱的NO3--N运移过程不存在非物理平衡现象。在溶质运移中,对流是为主要的运移方式。NH4+-N的穿透过程中存在化学非平衡现象,两点模型(T-S)可以较好地拟合NH4+-N的运移过程。土壤质地是影响NO3--N运移最主要的因素。平均孔隙流速随着容重的增加呈负指数函数关系递减,初始穿透时间和完全穿透时间与容重之间可以用多项式函数进行描述。弥散度随着砂粒含量的增加呈负指数函数关系递减,平均孔隙流速随着砂粒含量的增加呈指数函数关系增加,Pe数随着砂粒含量的增加呈线性函数的关系增加,说明质地越粗的土壤,溶质运移运移的主要方式更倾向于对流。土壤理化性质中阳离子交换量(CEC)和土壤质地是影响NH4+-N运移最主要的因素。阻滞因子(R)与砂粒含量和平均孔隙流速呈极显著负相关关系,与阳离子交换量、容重、粉粒和粘粒含量呈极显著正相关关系。阻滞因子与阳离子交换量和平均孔隙流速间可分别使用指数函数和幂函数关系进行描述。(4)添加砒砂岩可以阻滞溴离子和钠离子在风沙土中的运移,阻滞效应随着砒砂岩含量的增加愈明显。两种离子的穿透时间均随着砒砂岩含量的增加而延长;钠离子穿透过程中为达到相同相对浓度,所需的孔隙体积数也随着砒砂岩含量的增加而增大。CDE模型和两区模型(T-R)可以较好地拟合Br-穿透曲线,两区模型拟合的精度略好于CDE模型;拟合参数显示对流是土柱中主要的运移方式;两点模型(T-S)可以较好地模拟Na+穿透曲线。分析砒砂岩对风沙土阻滞溶质运移的原因主要是:添加砒砂岩可以降低土壤的平均孔隙流速;砒砂岩中含有较高含量蒙脱石,同时CEC含量高于风沙土,导致砒砂岩对钠离子具有较强的吸附能力。(5)添加砒砂岩作为隔层可以阻滞溶质在土柱中的运移,随着砒砂岩厚度的增加阻滞效果越好。CDE模型和两区模型(T-R)可以较好地拟合Br-穿透曲线,两区模型拟合的精度略好于CDE模型;拟合参数显示对流是土柱中主要的运移方式。层状土的水动力弥散系数不是简单的均质土体的水动力弥散系数的平均值,层状土的弥散度与均质土体弥散度之间的关系尚不明确。两点模型(T-S)可以较好地模拟Na+穿透曲线,拟合得出的砒砂岩阻滞因子远大于黄土及土石混合结构,随着砒砂岩隔层厚度的增加阻滞因子也增大,因此可以选择合理厚度的砒砂岩隔层阻滞溶质的运移。(6)添加砒砂岩可以降低新构土体的入渗性能。砒砂岩的入渗能力低于黄土和风沙土,黄土和风沙土中分层填装或均匀混合添加砒砂岩的方式均可降低其入渗能力;黄土与料姜石以及黄土与煤矸石的土石混合结构在土石质量比为70:30、容重分别为1.61 g/cm3和 1.54 g/cm3时拥有较低的入渗能力。入渗过程中湿润锋推进距离与累积入渗量间的关系可采用线性函数进行表达;利用Philip方程和Kostiakov入渗模型均可以较好地拟合均质土体的入渗过程,Kostiakov入渗模型对层状结构土体也有较好地拟合结果。表层为50cm黄土、中间20cm砒砂岩,下层设置容重较高的土石混合结构可以作为一种良好的排土场重构结构,为土石混合结构水分运动提供了一定的理论基础。
[Abstract]:Jin-Shan-Mong energy region is an important energy base in China, coal mining brings economic benefits but also caused great damage to the local environment, and the area is arid, semi arid ecological fragile zone, land reclamation is a need for better understanding. And the new structure of soil moisture and solute transport effects on soil quality in coal mining, this paper through the analysis of the soil quality evaluation of different land use types of soil profile were analyzed. The effects of vegetation restoration on soil total nitrogen and organic matter content; analysis the impact of different land use types in different soil solute transport characteristics and transport parameters of different sandstone adding factors; the content on soil solute transport and the influence of sandstone thickness as the interlayer add effects on stackpile soil solute transport simulation, the different configurations of soil Mixed layer structure and mixed structure of embankment reclamation soil infiltration process, the main conclusions are as follows: (1) compared with the local grassland farming, due to coal mining, reclamation row soil quality soil field appear different degree of degradation. The main performance is: the soil texture become coarse, mostly sandy loam soil; soil bulk density changed, 20-60 cm soil bulk density, soil bulk density decreased below 60 cm soil; P H increased nearly 8.5; soil CEC, organic matter and total nitrogen content is lower than that of grassland; stackpile and non stackpile soil nitrate nitrogen, ammonium nitrogen, total phosphorus, total potassium content distribution is irregular. With the grassland, farmland soil quality improved. Farmland, East dump black locust forest, East dump grassland, North stackpile grassland, North stackpile poplar forest soil degradation index were 14.18%, -13.56%, -8.75%, -25.63%, -24.91%. (2) in the dump Selection of vegetation restoration, compared with irrigated tree plants, a stronger effect on the increase in soil nitrogen and organic matter content of herbaceous plants, especially good to improve the effect of Astragalus adsurgens, alfalfa and other legume plants on soil nitrogen and organic matter. Poplar samples of total nitrogen and organic matter content are the lowest, that improve the effect of poplar on soil total nitrogen content not good. The top 0-10 cm soil total nitrogen and organic matter content is higher than 10-20 cm soil content showed vegetation is more obvious in 0-10 cm soil improvement effect. With the increase of reclamation time, the content of soil nitrogen and organic matter increased. (3) the migration characteristics of different land use types and different soil depth column NO3--N and NH4+-N two kinds of ions, and the transport parameters were simulated using the model. The main factors that affect the solute transport. The surface (0-20 cm) soil column in deeper soil column average wear Through a short time, the other the depth of soil column breakthrough time distribution is not obvious.NH4+-N penetration time is NO3--N through time, and the presence of smearing. Equilibrium model of CDE NO3--N migration process is two (T-R) better fitting effect, NO3--N migration process of different soil column does not exist non physical phenomenon. In the solute balance migration, convection is the main way of penetration in the process of.NH4+-N migration in the presence of chemical non equilibrium phenomena, two models (T-S) can be used to fit the NH4+-N migration process. The soil texture is the main factor to affect the migration of NO3--N. The average pore velocity with a negative exponential function relationship decreasing increasing bulk density, and initial penetration time full penetration between time and density can be described by a polynomial function. The dispersion with a negative exponential function relationship of diminishing sand content increased, the average pore flow velocity increases with the With the exponential increase of sand content, the number of Pe increased linearly with the function of sand content increased, indicating more coarse soil texture, the main way to solute transport migration tend to convection. Soil physical and chemical properties of cation exchange capacity (CEC) and the soil texture is the main influencing factors of NH4+-N migration. The retardation factor (R) showed a significant negative correlation with sand content and average pore velocity, and cation exchange capacity, bulk density, positive correlation was found between the silt and clay content. The amount and average pore velocity can be respectively used exponential function and power function description block factor and cation exchange. (4) add feldsparthic sandstone can block bromide and sodium ion transport in sandy soils, blocking effect with increasing content of sandstone is more obvious. Two kinds of ion penetration time with sandstone content Increased; sodium ion penetration process to achieve the same relative concentration, the pore volume of the required number increases with the increase of the content of sandstone model and.CDE model two (T-R) can better fit the breakthrough curves of Br-, the two region model fitting precision is slightly better than the CDE model; the fitting parameters show convection is the main way of migration in the soil column; two models (T-S) can be used to simulate the breakthrough curves of Na+. Analysis on soil solute transport block sandstone is mainly added in sandstone can reduce the average pore velocity of soil; feldsparthic sandstone rock containing high content of montmorillonite, while CEC was higher than that in sandy soil, cause sandstone has a strong adsorption capacity of sodium ions. (5) add feldsparthic sandstone as interlayer can block the solute migration in soil columns, with the increase of the thickness of sandstone model block better the effect of the.CDE model and the two district (T -R) can better fit the breakthrough curves of Br-, the two region model fitting precision is slightly better than the CDE model; fitting parameters showed that the convection was the main way of migration in the soil column. The average hydrodynamic dispersion coefficient of hydrodynamic dispersion coefficient of layered soil is not a simple homogeneous soil with the value of the relationship between the degree of dispersion and layered soil homogeneous soil dispersion is not clear. The two models (T-S) can be used to simulate the breakthrough curves of Na+, sandstone block factor fitting is far greater than the Loess and soil rock mixture structure, also increases with the increase of retardation factor in sandstone thickness of the interlayer, the migration so you can select the reasonable thickness of sandstone layer block. (solute 6) add new structure in sandstone can reduce soil infiltration. The infiltration capacity is lower than that of loess and sandy soil in sandstone, loess and sandy soil in layered filling and mixing way add sandstone Can reduce the infiltration capacity of loess and stone material; ginger and loess and coal gangue mixture structure in rock mass ratio was 70:30, the bulk density respectively have lower infiltration capacity of 1.61 g/cm3 and 1.54 g/cm3. In the process of infiltration wetting front and infiltration cumulative relations between the linear the function of expression distance; using the Philip equation and the Kostiakov infiltration model can better fit the infiltration process of homogeneous soil, Kostiakov infiltration model has good fitting results of layered soil structure. The surface is 50cm loess, middle 20cm sandstone, debris mixed structure of the lower layer is provided with high density can be used as a good dump structure reconstruction, provides a theoretical basis for the mixture structure of water movement.

【学位授予单位】：中国科学院研究生院(教育部水土保持与生态环境研究中心)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S151.9

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