控制排水条件下农业非点源污染物流失特征

Loss characteristics of agricultural non-point source pollutants under controlled drainage

通过在宁夏回族自治区青铜峡灌区进行的自由排水与控制排水的对比监测试验,系统分析了控制排水条件下排水量以及农田排水中盐分、总磷、硝酸盐氮、氨氮浓度和负荷的变化特征,分析了控制排水的节排减污机理。研究结果表明:相比于自由排水,控制排水在稻田生长期可累计减少排水43.01%,并降低农田排水中各类污染物浓度,盐分、总磷、硝酸盐氮、氨氮浓度分别减少7.68%、17.39%、18.16%、9.20%;农田排水中盐分、总磷、硝酸盐氮、氨氮污染负荷相应减少46.49%、44.46%、57.51%、38.89%;污染负荷的减少是排水量减少和污染物浓度降低共同作用的结果,其中排水量减少起主要作用,污染物浓度降低是次要因素。

The contrast test of monitoring uncontrolled drainage and controlled drainage were carried out at the Qing Tong Xia Irrigation District in Ningxia Hui Autonomous Region.The concentration and load variation characteristics of salinity,total phosphorus,nitrate-nitrogen and ammonia-nitrogen in farmland drainage under controlled drainage condition were analyzed,and the mechanism of reducing drainage and sewage was discussed.The results showed that comparing to uncontrolled drainage,with controlled drainage,the drainage amount would reduce by 43.01%,the concentration of salinity,total phosphorus,nitrate-nitrogen and ammonia-nitrogen would reduce by 7.68%,17.39%,18.16%,9.20% respectily,and the pollution load would reduce by 46.49%,44.46%,57.51%,38.89% respectively.The reduction of pollution load results from joint actions of drainage reduction and pollution concentration decrease.The drainage reduction plays the leading role and pollutant concentration decrease is the secondary factor.