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| Spatio-temporal variation of nitrogen and phosphorus contents in cascade ponds in subtropical headstream watershed and its influencing factors |
| Received:November 15, 2019 |
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| KeyWord:cascade ponds;nitrogen;phosphorus;spatial-temporal variation;land use;fish farming |
| Author Name | Affiliation | E-mail | | SHEN Ya-li | College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China
School of Urban and Environmental Sciences, Huaiyin Normal University, Huai'an 223300, China
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | | | ZHOU Jiao-gen | School of Urban and Environmental Sciences, Huaiyin Normal University, Huai'an 223300, China
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | zhoujg@hytc.edu.cn | | PENG Pei-qin | College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China | | | WU Jin-shui | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China | |
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| Abstract: |
| The study of spatial-temporal variability of nitrogen and phosphorus in cascade pond systems helps to understand the mechanism of occurrence of non-source N and P pollution in ponds of agricultural watersheds. The typically subtropical hilly watershed of Jinjing was used as the study region. The total nitrogen(TN)and total phosphorus(TP)concentrations were measured in 18 groups of cascade ponds(36 ponds in total)from June 2017 to May 2018. The spatial-temporal variability and its drivers of TN and TP contents were explored using the observations of the consecutive 12 months. The averaged TN concentrations were lower in the upstream ponds(1.86 mg·L-1)than those in the downstream ponds(2.56 mg·L-1), and the upstream TP contents were close to the downstream ones. Generally, high TN and TP contents occurred in upstream and downstream ponds during the dry seasons. The pollution of TN and TP was serious in the observed ponds. According to the national surface water quality standard, the water quality of more than 72.8% of observations in upstream and downstream ponds worse than the Class Ⅲ of surface water standard. The TN and TP contents in the cascade ponds were affected by the surrounding landuse types and fish farming. Compared to non-fish farmed ponds, fish farming increased the TN and TP contents by 60% and 34%, respectively. The study suggestes that agricultural land use and fish farming exacerbate the deterioration of the water quality of TN and TP in cascade pond systems. Strengthening the prevention and control of non-source pollution from farmland and aquaculture management will help the improvement of the water quality of TN and TP in ponds of the subtropical agricultural watershed. |
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