外源凹凸棒土添加对半干旱矿区复垦土壤水分涵养功能的影响

大规模的采矿作业已对我国半干旱区植被生态造成很大破坏,矿区植被亟待恢复,以解决半干旱矿区日益恶化的生态环境问题。如何改良土壤、有效储存和利用降水是半干旱矿区复垦土地植被恢复的首要问题。本研究针对半干旱矿区复垦土地水分涵养功能不足的问题,提出利用凹凸棒土和当地砂土组配作为新覆土材料,并研究了外源凹凸棒土添加对神木矿区复垦土壤入渗、排水和储水能力的影响。结果表明: 随着凹凸棒土含量的增加,土壤的累积入渗量减少4.8%～37.4%,入渗率减少6.4%～46.3%,湿润锋推进速度减小9.8%～116.9%,饱和导水率减小14.3%～59.5%,24 h和72 h排水量分别减少0.3%～4.3%和0.3%～2.5%,土壤最大储水量增加1.6%～22.4%。外源凹凸棒土的作用效果在添加量为150 t·hm^-2时基本已达到最大,结合经济成本的最佳用量在30～150 t·hm^-2。本研究结果系统揭示了凹凸棒土对半干旱矿区土壤减渗保水的作用机理,证明其可以作为半干旱矿区复垦土壤改良的有效材料,为半干旱矿区土地复垦和植被恢复提供参考。

Effects of exogenous attapulgite addition on water conservation function of reclaimed soils in a semi-arid mining area

Large-scale mining has greatly damaged vegetation and caused ecological degradation in the semi-arid area in China. It is urgent to restore the vegetation to solve the deteriorating ecological and environmental problems in mining area. How to reclaim soils for effectively storing and utilizing precipitation is the primary issue for vegetation restoration in the area. In this study, we proposed to take the mixture of attapulgite clay and local sandy soils as covering materials to improve the weak water conservation function of soils in mining areas, and studied the effects of the addition of attapulgite clay on soil infiltration, drainage and water storage sampled from the Shenmu mining area. The results showed that, with increasing application rates of attapulgite clay, the cumulated infiltration volumes decreased by 4.8%-37.4%, the infiltration rates dropped by 6.4%-46.3%, the wetting front advance rates decreased by 9.8%-116.9%, the saturated hydraulic conductivities decreased by 14.3%-59.5%, the drained water volumes reduced by 0.3%-4.3% for 24 hours and by 0.3%-2.5% for 72 hours, and the maximum soil water storages increased by 1.6%-22.4%. The maximum effect of attapulgite clay peaked at the application rate of 150 t·hm^-2. Considering the economic cost, the optimum application rate should be 30-150 t·hm^-2. The results syste-matically revealed the mechanism of reclaiming mining soils with attapulgite clay to restore the function of water conservation, and demonstrated that attapulgite clay is an effective material for soil reclamation in the semi-arid mining area, which can provide references for soil reclamation and ecological restoration in the semi-arid mining area.