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| DOI：10.13522/j.cnki.ggps.2020207 |
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| Efficacy of a Sedimentation-boosting and Purifying Device for Decontaminating Pollutants in Surface Runoff from Paddy Field |
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FU Zishi, SUN Huifeng, ZHOU Sheng, ZHANG Jining, ZHANG Xianxian, WANG Cong
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1. Shanghai Academy of Agricultural Science, Shanghai 201403, China;2. Shanghai Engineering Research Centre of Low-carbon Agriculture, Shanghai 201415, China
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| Abstract: |
| 【Background】 The catchment of Tai lake is one of the most important rice production basins in China and rice-wheat rotation is its dominant cultivation. However, excessive use of water and fertilizers has led to nutrient loss and eutrophication. Since precipitation in the catchment is high and most of it fall during the rice growth season, nutrients leaching with runoff into rivers is one of the main non-point source of pollutants in the catchment. 【Objective】 The objective of this paper is to present a sedimentation-boosting and purifying device and study its efficiency for in situ removing the pollutants in runoff from rice fields.【Method】The experiment was conducted in 2015 at five paddy fields in Qingcun town, Fengxian district of Shanghai. A set of sedimentation-promoting and purifying devices each with a volume of 1.9 m3 were installed at the outlet of the drainage system in each field. The device was filled with plastic polyhedron hollow balls and zeolite at a volumetric ratio of 1∶2 in its inside part, and its outside part was filled with zeolite. During the experiment, we measured the concentrations of suspended solids, total nitrogen and total phosphorous in both inflow and outflow of the device.【Result】 The removal efficiencies of the suspended solids, total nitrogen and phosphorous by the device during the rice growth season were 61%, 33% and 34%, respectively. The removal efficiency of suspended solids and total phosphorus by the device was positively correlated with their concentrations in the inflow in a logarithmic form, while the removal efficiency of total nitrogen was negatively correlated to its concentration in the inflow. 【Conclusion】 The sedimentation-promoting and purifying device can effectively remove main pollutants in the runoff from the paddy fields. It can thus improve the aquatic ecosystem without affecting the drainage from the paddy fields. |
| Key words: sedimentation-promoting and purifying device; total nitrogen; total phosphorus; non-point source pollution; surface runoff; paddy field |
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