含氮污水灌溉实验研究及污染风险分析

在野外实验基地进行的含氮污水灌溉实验工作基础上,分析了污灌过程中氮化合物在土壤及地下水中迁移转化规律.研究结果表明,污灌对下层土壤及地下水中NH₄+浓度影响较小,但对NO₃-浓度影响较大,尤其是长期进行污灌的土壤,易造成地下水中NO₃-污染.利用本文推导的数学模型,可以定量预测污水灌溉后土壤水及地下水中NH₄+、NO₃-浓度的时空变化.采用Monte-Carlo法,进行含氮污水灌溉污染风险分析,结果表明,进入地下水的NO₃--N最大浓度超过污灌水NO₃--N浓度0.76倍的可能性为25%、超过污灌水NO₃--N浓度0.43倍的可能性为75%,污灌造成的地下水NO₃-污染风险必须引起注意.

Nitrogen wastewater irrigation study and its contamination risk analysis

Based on the nitrogen wastewater irrigation experiments carried out in the field experimental base,the movement and transformation regularities of nitrogen compound in wastewater irrigation were analyzed in this paper.The results showed that wastewater irrigation had a little influence on the ammonium concentration in deep-depth soil solution,but a big influence on the nitrate concentration in groundwater,especially in the soil with seriously wastewater irrigation before.The mathematical model,which was developed in the paper,could be used to predict the temporal and spatial distribution of ammonium-N and nitrate-N in soil solution and groundwater.The groundwater contamination risk analysis was conducted by using the Monte-Carlo simulation techniques.It is noteworthy that the maximum nitrate-N concentration at 5m depth of groundwater level is predicted to be great than 0.76 times of nitrate-N concentration in irrigated wastewater with 25% probability,and great than 0.43 times with 75% probability.Groundwater contamination risk should be considered in wastewater irrigation.