不同入流条件下草本缓冲带对污染物削减作用

草本缓冲带能够有效拦截坡面径流中泥沙、总氮、总磷等污染物,是农业面源污染防控的主要措施之一。通过人工配水模拟地表径流,研究不同径流量对草本缓冲带截污能力的影响。结果表明:草本缓冲带对污染物都有一定的削减作用,草本缓冲带对泥沙削减效果最好,对总磷削减效果最差,白三叶对污染物的削减能力总体较黑麦草强。径流量对草本缓冲带总氮、总磷削减率影响较大,对泥沙削减率影响较小;当流量从0.08 L/s增加至0.24 L/s时,草本缓冲带对总氮、总磷削减率减少至9%和6%,而泥沙削减率为34%。随着放水冲刷时间增加,出流总氮、总磷、泥沙浓度不断降低并逐渐达到稳定,流量增大至0.24 L/s时,总氮、总磷浓度范围为11.5~24.7,1.6~2.3 mg/L,泥沙浓度在不同流量下无明显差异。草本缓冲带对总氮、总磷去除作用受流量影响较大,在大流量时缓冲带对总氮、总磷基本无去除作用,但缓冲带对泥沙去除作用受流量影响较小。

Effect of Herbal Buffer on Pollutant Reduction Under Different Inflow Conditions

Herbal buffer zone can effectively intercept pollutants such as sediment, total nitrogen, total phosphorus and other pollutants on slope, which is one of the main measures to prevent and control agricultural non-point source pollution. The surface runoff was simulated by artificial water distribution, and the effects of different runoff on interception capacity of herbaceous buffer zone were studied. The results showed that the herbal buffer had a certain reduction effect on pollutants. The herbal buffer had the best effect on sediment reduction and the worst effect on total phosphorus reduction. White clover had a stronger ability to reduce pollutants than ryegrass. Runoff had a greater impact on the reduction rate of total nitrogen and total phosphorus in herbal buffer zone, but a little impact on sediment reduction rate. When the flow rate increased from 0.08 L/s to 0.24 L/s, the reduction rate of total nitrogen and total phosphorus in herbal buffer zone decreased to 9% and 6%, while the sediment reduction rate was 34%. With the increasing of discharge scouring time, the concentration of total nitrogen, total phosphorus and sediment in the outflow decreased and gradually reached a stable level. When the flow rate increased to 0.24 L/s, the concentration range of total nitrogen and total phosphorus were 11.5~24.7 and 1.6~2.3 mg/L, respectively. There was no significant difference in sediment concentration under different flow rates. In this study, the removal of total nitrogen and total phosphorus by herbal buffer zone was greatly affected by the flow rate, and the buffer zone had no removal effect on total nitrogen and total phosphorus at large flow rate, but the removal of sediment by buffer zone was less affected by the flow.