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| Removals of pollutants in surface runoff from sloping farmland using different hedgerow systems |
| Received:December 01, 2015 |
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| KeyWord:hedgerow;sloping farmland wastewater;pollutant;removal efficiency |
| Author Name | Affiliation | E-mail | | LIU Qiang | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | DENG Shi-huai | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | 453075784@qq.com | | JING Zi-hui | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | LUO Chun-yan | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | ZHOU Xin | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | CHENG Hong-chun | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | LIANG Zhi-qiang | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | | | WANG Zi-lin | College of Environment, Sichuan Agricultural University, Chengdu 611130, China | |
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| Abstract: |
| Four hedgerow systems were designed to examine their removal efficiencies of TN, TP, NH3-N, TOC and COD in surface runoff from farm land with different slopes(5°, 10°, 20°) at different influent concentrations(low, medium, high). The hedgerow systems included photinia fraseri + lobular privet + ryegrass(T1); photinia fraseri + lobular privet(T2); lobular privet + ryegrass(T3) and photinia fraseri + ryegrass(T4). Results showed that the removal efficiencies of the pollutants, especially TP, NH3-N and COD, by these 4 hedgerow systems all decreased with increasing slopes. When the slope increased from 5° to 20°, the removal rates decreased from 52.25%~76.75% to 33.68%~60.34% for TP, 36.84%~68.33% to 34.30%~45.46% for NH3-N and 13.26%~38.69% to 3.15%~26.74% for COD, respectively. Increasing influent concentrations increased the pollutant removal efficiencies by the hedgerow systems with an exception of NH3-N. The removal rates of TP, TOC, COD by the hedgerows increased from 33.33%~60.11% to 57.06%~81.44%, -0.84%~2.92% to 9.64%~17.69% and -14.75%~11.25% to 20.62%~42.33%, respectively. as compared with the bare soil system. The removal rates of TN, TP, NH3-N, TOC and COD by hedgerow systems were significantly higher than those in the bare soil, with the maximum removal rates increased from 12.81% to 47.02% 34.29% to 76.75%, 18.27% to 68.33%, -0.93% to 11.52%, and 2.31% to 38.69% under different slopes and from 15.57% to 53.05%, 37.93% to 81.44%, 17.60% to 64.05%, 2.92% to 17.69% and -33.40% to 11.25% at different influent pollutant concentrations, respectively. Overall, the average removal rate of pollutants by 4 hedgerow systems was in order of T1>T4>T3>T2, which was related to the high surface coverage, the developed root systems and the interaction among three plants to retard the pollutants. |
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