不同生态修复模式下土壤水文性质及其对溶质运移的影响

煤矿区生态修复过程中不可避免地改变了土壤水和溶质运移过程.土壤水是溶质运移的主要载体,溶质运移受土壤水文性质与植被状况影响.以我国北方典型半干旱区山西古交矿区草本、灌草和乔灌草3种不同生态修复区和撂荒地的土壤为研究对象,揭示不同生态修复模式下土壤水文性质变化规律及其对溶质运移的影响.结果表明,土壤持水性从大到小依次为乔灌草地灌草地草地撂荒地,草本、灌草和乔灌草3种植被修复区的土壤持水量相对于撂荒地分别增加了33.79%、59.19%和62.71%,植被修复有助于增加土壤层蓄水能力.土壤饱和导水率由大到小依次为草地(1.736 mm·min~(-1))灌草地(1.678 mm·min~(-1))乔灌草地(1.564 mm·min~(-1))撂荒地(1.012 mm·min~(-1)),非饱和导水率随吸力增大而呈指数下降,植被修复过程中降低容重的同时提高了土壤持水性,改善土壤持水性能.不同生态修复区土壤中溶质穿透时间呈草地灌草地乔灌草地撂荒地的趋势.CDE、SC和TRM模型均可对矿区不同生态修复模式土壤的溶质运移过程进行较好的表达,其中CDE模型拟合效果最好.结果表明研究区溶质运移方式以对流为主,而且土壤容重和砂粒含量是影响溶质运移的主要因素.

Soil hydrological properties and their effects on solute transport under different ecological restoration models in coal mining area

The transport process of soil water and solute are inevitably changedduring ecological restoration of mining areas. Soil water is the main carrier of solute transport. Which is affected by soil hydrological properties and vegetation status. Investigation and describing soil hydrological properties and solute transport process in unsaturated zone is one of key scientific issues during the process of ecosystem restoration in mining area. In this study, herbaceous, shrubs, arbors, shrubs and grasses vegetation restoration areas and abandoned wasteland in Gujiao mining area of Shanxi Province were selected as the research objects. By monitoring soil physical and chemical properties and hydraulic parameters under different ecological restoration modes, soil hydrological properties were revealed in ecological restoration areas. The migration process and transport characteristics of solute under different ecosystem restoration modes were simulated by CDE, TRM and SC models. effects of soil hydrological properties on solute transport were investigated under different ecological restoration models in coal mining. The results show that soil water-holding capacities ranked as follows:arbors-shrubs-grasses > shrubs-grasses area > herbaceous area > abandoned wasteland area. Soil saturated water conductivity ranked as follows:herbaceousarea > shrubs-grassesarea > arbors-shrubs-grasses > abandonedwastelandarea. Compared with that of abandoned land, the water holding capacity of herbaceous, irrigated grass and arbor irrigated grass increased by 33.79%, 59.19% and 62.71%, respectively. After ecosystem restoration, there was a significant positive correlation between bulk density and soil water holding capacity. Vegetation reduced bulk density and improved soil water holding capacity. The unsaturated water conductivity decreased exponentially with the increase of suction. Solute penetration time of different ecological restoration models are in the following:herbaceous area(1.736 mm·min^-1) > shrubs-(1.678 mm·min^-1) > arbors-shrubs-grasses(1.564 mm·min^-1) > abandoned wasteland area(1.012 mm·min^-1).CDE, SC and TRM model can better express the transport process of solute under different ecological remediation modes in the mining area, especially CDE. Convection was the main transport mode, and bulk density and sand content were the main factors affecting solute transport in mining area.