生态塘对稻田降雨径流中氮磷的拦截效应研究

Study on the interception effects of ecological pond on Nitrogen and Phosphorus in the rainfall runoff of rice field

农田养分的大量流失已成为农业面源污染的主要来源之一,生态塘兼具排水和生态湿地双重功效,研究其对稻田排水氮磷的拦截效应对于防治农业非点源污染具有重要意义。针对降雨径流条件下生态塘对降雨径流中氮磷的动态拦截效应以及降雨径流结束后氮磷在静水中的去除效应有待明了的需求,本文选取太湖西岸何家浜流域典型农田作为研究对象,并将该区域的塘堰改造为生态塘,研究了生态塘对水稻生长期内的三场降雨径流氮磷的拦截去除效果及降雨径流结束后氮磷在静水中的去除效应。研究结果表明:(1)在三场降雨过程中,生态塘对总氮(TN)的平均去除率为34.7%,总磷(TP)的平均去除率为34.8%;(2)生态塘对降雨径流中不同形态氮磷的去除率大小排序为氨氮(NH_4^+-N)>颗粒态氮(PN)>硝态氮(NO_3^--N),颗粒态磷(PP)>溶解态磷(DP),且径流状态下水体垂向分层氮磷浓度分布随降雨进行而变化,总体分布规律为底层氮磷浓度大于表层氮磷浓度;(3)降雨径流结束后,TN在生态塘中的去除率为50.4%,TP在生态塘中的去除率为52.3%,塘2对TN、TP的去除率大于塘1与塘3,生态塘表现了较强的抗冲击自修复性。

The ecological pond has double effects on drainage and ecological wetland.With huge loss of farmland nutrient becoming one of the main sources of agricultural non-point source pollution,it is significant to study the interception effects of ecological pond on nitrogen and phosphorus in the rainfall runoff of rice field and the removal effect on nitrogen and phosphorus in static water.In this paper,the ecological pond was built based on the transformation of natural pond,and the interception effects of ecological pond on nitrogen and phosphorus in the three rainfall runoff events happened in rice growth periods was studied.What＇ s more,the removal effects of ecological pond on nitrogen and phosphorus under stationary state of the ecological pond water was also studied.The results show that：（l） in the process of three different rainfall events,the average removal rate of total nitrogen（TN） and total phosphorus（TP） by ecological ditch are 34.7%and 34.8%respectively;（2） the sort order of nitrogen and phosphorus removal rate by ecological ditch is ammonia nitrogen（NH4^＋-N） grain nitrogen（PN） nitrate nitrogen（NO3--N） and particles phosphorus（PP） 〉dissolved phosphorus（DP）,and the concentration of nitrogen and phosphorus in different water body vertical stratifications are varied during rainfall runoff,but the concentration of nitrogen and phosphorus in the underlying water body is mostly greater than that in the surface water body;（3） after the rainfall runoff,the removal rate oi TN and TP in ecological pond are 50.4%and 52.3%respectively.and the removal rate of pond 2 on TN and TP is greater than pond 1 and pond 3,indicating that the ecological pond has a strong self-repairing ability.