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| Effects of reclaimed water irrigation on the distribution of heavy metal in paddy fields |
| WANG Lei1*, ZHOU Luyao2, HU Jingbo3, CAI Jiafang1, WANG Wei4, XIAO Wanchuan1, HE Miaomiao5 |
| 1. Zhejiang Institute of Hydraulics and Estuary(Zhejiang Institute of Marine Planing and Design), Hangzhou, Zhejiang 310020, China; 2. Zhejiang Water Resources and Hydropower Management Center(Zhejiang Water and Soil Conservation Monitoring Center), Hangzhou, Zhejiang 310000, China; 3. Hangzhou Xiaoshan Water Conservancy and Hydropower Survey and Design Co., Ltd., Hangzhou, Zhejiang 311200, China; 4. Hangzhou Yuhang District West Water Conservancy Comprehensive Service Center, Hangzhou, Zhejiang 311100, China; 5. Water Affairs Bureau in Wuzhong District, Suzhou, Jiangsu 215104, China |
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Abstract Based on the field experiment, the paddy field in South China was taken as the research object, aiming at the safe irrigation regulation of reclaimed water, the effects of different irrigation water sources(rural domestic sewage primary treatment water R1, secondary treatment water R2, ecological pond purified water R3 and river water R4)and irrigation regulations(low water level control W1, medium water level control W2 and high water level control W3)on the changes of typical heavy me-tals(Cd, Pb, Cr, Cu, Zn)in soil and crops were studied, and the ecological risk of rural domestic reclaimed water irrigation regulation on soil heavy metals was analyzed. The results show that the contents of Cd and Pb are increased slightly, but the contents of Cr, Cu and Zn are decreased in paddy field. The contents of heavy metals in rice organs are shown that stem> grain≈leaf. The composition of heavy metals is shown that Zn>Cr>Pb>Cd. Compared with irrigation water sources, water level regulation has little effect on the accumulation of heavy metals in rice organs. The content of heavy metals in rice grain is not increased significantly under reclaimed water irrigation, which meets the limit requirements of pollutants in rice grains. The ecological risk coefficient of Cd in paddy fields under rural domestic sewage reclaimed irrigation is the highest, followed by that of Cu and Pb, the risk coefficient of Cr and Zn is relative lower, and the potential ecological risk under R3 water sources is the lowest. In general, serious pollution to paddy field is not caused by reclaimed water irrigation, but whether a continuous increase in the risk of heavy metal pollution will be caused remains to be studied by long-term reclaimed water irrigation.
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Received: 15 October 2021
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