包气带黏性土层对氮素污染地下水的防污性能试验研究

包气带土层是保护地下水的天然屏障，在阻控、拦截氮素污染源的过程中起到了重要作用。通过对北京市典型地区包气带土体进行定水位入渗的土柱淋溶试验，研究土体对于氮素的去除能力和包气带的截污容量。试验中采用了蒸馏水、再生水和河水3种不同的水源。试验结果显示，张家湾包气带土层对氮素污染地下水具有较强的截留和防护能力。对氮素的去除过程具有分段性特征，经历了较稳定和波动下降两个不同的阶段，其中稳定阶段是计算柱体去除能力的关键，提出了考虑滞后区间的时段去除率计算公式。水源对柱体的渗流速度及初期的吸附解析效应有明显影响。土体对氮素的去除作用受环境温度变化的影响，温度15 ℃左右时所达到的稳定阶段对氮素有极强的去除能力。

Experimental Study on the Filtration Capability of Clayey Soils in the Vadose Zone Prevention Nitrogen from Polluting Groundwater

The soil of unsaturated zone acts as a natural protector to the groundwater and it plays an important role in blocking the pollutants. Antifouling property in prevention nitrogen from polluting groundwater has been investigated through soil column leaching experiments. Three different sources-distilled water, recycled water and river water are used in the test. It is demonstrated that the soil used in the test has a strong capability in prevention nitrogen from polluting groundwater and the denitrification shows two different stages-stable and vola-tility dropped wherein the stable phase is the critical stage to compute the capacity. This papers presented a formula which considered the interval removal. The water sources have a significant effect on the flow rate and adsorption effects. The capability is affected by temperature changes. The column showed a strong ability to remove nitrogen when the temperature reached about 15 ℃.