模拟降雨条件下农田氮素径流流失特征研究  

Nitrogen loss characteristics of farmland runoff under simulated precipitation conditions

作　　者：薛鹏程[1,2] 庞燕[1] 项颂[1] 胡小贞[1] 王欣泽[3] XUE Peng-cheng PANG Yan XIANG Song HU Xiao-zhen WANG Xin-ze(Chinese Research Academy of Environmental Sciences, Beijing 100012, China Suzhou University of Science and Technology, Suzhou 215009, China Shanghai Jiaotong University, Shanghai 200240, China)

机构地区：[1]中国环境科学研究院,北京100012 [2]苏州科技大学,江苏苏州215009 [3]上海交通大学,上海200240

出　　处：《农业环境科学学报》2017年第7期1362-1368,共7页Journal of Agro-Environment Science

基　　金：国家水体污染控制与治理科技重大专项(2012ZX07105-003-03)~~

摘　　要：基于洱海流域农田径流总氮污染严重、入湖总氮负荷较高的特点,采用室外人工模拟降雨方法,研究了20、40、60 mm·h^(-1)三种雨强条件下农田径流产流过程和氮素流失特征。结果表明:农田径流的产生主要受降雨量控制,当雨量达到(20±2)mm时才会产生径流,雨强主要影响其产流后流量的增长速度以及稳流后流量的大小,雨强越大,产流增长速度越快,平稳后径流量也越大;径流中氮素流失量与降雨量呈极显著线性相关(P<0.01),而且雨强越大,氮素流失速度越快,雨强60 mm·h^(-1)时线性拟合方程的斜率最大为1.28;三种雨强条件下均无明显的初期冲刷效应,不宜通过截留初期农田径流来控制农田径流氮污染;径流中氮素浓度随着降雨量增加先增大后减小,其浓度峰值受雨强影响较大,雨强大的浓度峰值高,且浓度峰值均出现在径流量趋于稳定时段附近;氮素浓度变化与悬浮物浓度变化呈极显著线性相关。建议通过加强水土流失管控及在湖周采取截蓄净化等措施有效控制洱海流域农田径流中的氮污染。Farmland runoff in the Lake Erhai Basin is characterized with a high concentration of total nitrogen, which produces a high input load of total nitrogen into Lake Erhai. Outdoor simulated precipitation experiments were carried out to study the farmland runoff process and nitrogen loss characteristics under the rainfall intensities of 20, 40 and 60 mm·h-1. The results indicated that the farmland runoff was mainly affected by the amount of rainfall. At a rainfall amount of（20±2）mm or more, farmland runoff appeared. Rainfall intensity had a significant effect on the rate of increase in runoff volume at the generation and stabilization stages. The volume and rate of increment increased with rainfall intensity. A significant linear correlation（P〈0.01）was observed between the nitrogen loss and the amount of rainfall. Moreover, the rate of nitrogen loss increased with an increase in rainfall intensity. The maximum slope of the linear regression function between nitrogen loss and the amount of precipitation was 1.28 at the intensity of 60 mm·h-1. The first flush effect of the nitrogen loss from the farmland runoff was not obvisous at the three modelled rainfall intensitives; therefore, intercepting the initial farmland runoff was not a suitable method for controlling the nitrogen pollution. The nitrogen concentration in the farmland runoff initially increased, and then decreased with the increase in rainfall amount.The peak concentration was greatly affected by the rainfall intensity, i.e., the stronger the intensity, the higher was the peak concentration. The concentration peak of total nitrogen appeared when the runoff approached the stabilization stage. A significant linear correlation was observed between the total nitrogen concentration and the suspended solid concentration in the runoff. These results suggest that the effective methods of controlling nitrogen pollution from farmland runoff in Lake Erhai basin include prevention of soil erosion, interception, and purification of the farmland runoff arou

关 键 词：模拟降雨 农田径流 雨强 氮素 

分 类 号：X592[环境科学与工程—环境工程]