污染河水中氨氮对浅层地下水的影响

氨氮是目前地表水和地下水的一个重要污染源.室内试验选用3种天然砂土作为渗透介质, 以生活污水模拟污染河水, 经过近1 0个月的土柱试验, 发现氨氮在粗砂中第1 7天达吸附饱和, 第1 8— 1 4 0天去除率小于1 0 %, 在中砂中第1 30—1 4 0天吸附饱和, 以后均发生解吸出水浓度大于进水浓度.野外实验凉水河的氨氮浓度为4 6.86mg/L和2 6.95mg/L时, 地下水的氨氮浓度均小于1.1 0mg/L, 表明凉水河对地下水的实际影响不如室内大, 原因是底泥、河床下部渗透介质的厚度和岩性以及河水渗漏量的影响.排污河还清试验表明, 排污河清淤、灌入清水后, 会很明显地把排污河下部渗透介质中的氨氮带到地下水中, 造成地下水的二次污染. 

Influence on Shallow Groundwater by NH4-N in Polluted River

NH_4-N pollution in surface water and groundwater is currently very severe. Experiment simulation of NH_4-N migration was carried out in a column filled with three kinds of natural sand under the reflux of domestic sewage. Adsorption saturation of NH_4-N in the column was reached within 17 days for the coarse sand and 130-140 days for the medium sand, suggesting the easiness of NH_4-N migration to groundwater. However, the field test in Liangshui River and its groundwater is incompatible with the experimental observation. When the concentration of NH_4-N reached 46.86 and 26.95 mg/L in Liangshui River, the groundwater has a NH_4-N concentration of less than 1.10 mg/L. The little influence of Liangshui River on the groundwater NH_4-N was attributed to the bottom mud, the thickness and character of the infiltration media underlying the river bed as well as the seepage quantity of the river. Importantly, the NH_4-N absorbed by the penetration media underlying the sewage-received river would be transported into the groundwater after addition of clean water and cleanup of the mud, causing a secondary pollution of groundwater.