矿区生态修复过程中不同立地类型土壤水动力学特性

目的]揭示矿区不同立地土壤水动力学特性及其影响因素,为矿区生态环境恢复治理提供科学依据。方法]基于矿区不同立地类型土壤水分特征曲线、非饱和导水率、孔隙度与紧实度等监测试验,揭示不同立地类型土壤持水性、有效水含量和导水特性等变化规律。结果]土壤持水性和供水性在受损区<修复3a区<修复5a区<修复10a区<修复15a区<未干扰区,但修复区20—40cm土壤持水性、供水性较0—20cm土壤低,修复效果不明显;土壤结构改善效果遵循受损区<修复区<未干扰区的变化规律,且修复区亚表层土壤结构改善效果不明显。采用指数函数拟合吸力和非饱和导水率效果较好(r2>0.95),相同吸力下,容重大而非饱和导水率较小;非饱和导水率和容重呈负相关,和孔隙度呈正相关且相关性随吸力增加降低。矿区0—20cm易有效含水量呈现受损区<修复3a区<修复5a区<修复10a区<未干扰区<修复15a区,但修复区20—40cm土层易有效水含量较0—20cm小。结论]土壤易有效水含量和容重、紧实度呈负相关关系,与总孔隙度、黏粒含量呈正相关关系。修复后土壤结构有所改善,持蓄调节水分能力有所提高。

Dynamic Characteristics of Soil Water in Different Sites During Ecological Restoration in Mining Area

Objective] To investigate the hydrodynamics characteristic of soil water in different sites in the mining area in order to provide a scientific basis for ecological restoration in the mining area.Methods] The soil water characteristic curves, unsaturated hydraulic conductivity, bulk density, porosity, particle size and compactness were measured to investigate characteristics of soil quality, water-holding capacity, readily available water content and water conductivity in different site types.Results] The capacity of soil water-holding and water-supplying exhibited as:damaged area < restoration for 3 years area < restoration for 5 years area < restoration for 10 years area < restoration for 15 years area < undamaged area, and soil water-holding capacity and water-supplying capacity at 20-40 cm was lower than that at 0-20 cm, which indicated that remediation effect was not obvious. The improvement of soil structure showed as:damage area < remediation area < undamaged area, and the improvement of subsurface soil quality in remediation area was not obvious. The exponential function fitting between suction and unsaturated hydraulic conductivity was good (r²>0.95). Under the same suction, the unsaturated hydraulic conductivity was smaller as:soil bulk density was greater. There was a negative correlation between unsaturated hydraulic conductivity and bulk density, while a positive correlation between unsaturated hydraulic conductivity and total porosity, and this correlation decreases with the increase of suction. Readily available water content of 0-20 cm exhibited as damage area < restoration for 3 years area < restoration for 5 years area < restoration for 10 years area < undamaged < restoration for 15 years area, and readily available water content of 20-40 cm soil layer was smaller than that of 0-20 cm.Conclusion] The readily available water content was negatively correlated with bulk density and compactness, and positively correlated with total porosity and clay content. The soil quality and water storage capacity had been improved through restoration progress.