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| Nitrogen loss characteristics of farmland runoff under simulated precipitation conditions |
| Received:March 16, 2017 |
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| KeyWord:simulated precipitation;farmland runoff;rainfall intensity;nitrogen |
| Author Name | Affiliation | E-mail | | XUE Peng-cheng | Chinese Research Academy of Environmental Sciences, Beijing 100012, China
Suzhou University of Science and Technology, Suzhou 215009, China | | | PANG Yan | Chinese Research Academy of Environmental Sciences, Beijing 100012, China | 190068749@qq.com | | XIANG Song | Chinese Research Academy of Environmental Sciences, Beijing 100012, China | | | HU Xiao-zhen | Chinese Research Academy of Environmental Sciences, Beijing 100012, China | | | WANG Xin-ze | Shanghai Jiaotong University, Shanghai 200240, China | |
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| Abstract: |
| 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 around the lake. |
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