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| Characteristics of salt-based ion release from small agricultural watersheds in the Three Gorges Reservoir area |
| Received:November 27, 2019 |
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| KeyWord:Three Gorges Reservoir;non-point source pollution;agricultural watershed;salt-based ions |
| Author Name | Affiliation | E-mail | | DOU Tian-yuan | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | LONG Juan | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | LIAO Yu-qin | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | MU Zhi-jian | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | muzj@swu.edu.cn | | CI En | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | WEI Shi-qiang | College of Resources and Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | |
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| Abstract: |
| In order to understand the agricultural non-point source load loss and discharge characteristics of salt-based ions, high-frequency (daily)monitoring of the runoff water quality of the two adjacent catchments in the Fuling section of the Three Gorges Reservoir area was conducted for 2 a. The climate and geomorphology of the two catchments were the same, but the paddy fields in one catchment were scattered and the fragmentation index was high(recorded as catchment area A). The fragmentation index was low. The results showed that the annual average output fluxes of anions and cations in catchment area A were 499 kg·hm-2·a-1 and 218 kg·hm-2·a-1, respectively, and the average annual output fluxes of anions and cations in catchment area B were 265 kg·hm-2·a-1 and 118 kg·hm-2·a-1, respectively. The saltbased ion output flux of catchment area A was approximately twice that of catchment area B. This difference was likely caused by the different distribution patterns of the paddy fields. Placing paddy fields on the bottom of the catchment area can reduce agricultural salt-based ion runoff. The dominant anions and cations in the runoff water body of the basin were Cl- and Ca2+, which accounted for 58% and 67% of the total anion and cation emissions, respectively. In terms of different crop seasons, the rice/maize season and mustard season each contributed approximately 50% of the annual salt-based ion emissions. In terms of different periods, the ion load was highest in May and November, accounting for 26% and 24% of the ion discharge load of the entire year, respectively. Studies have shown that May and November are the key time nodes to control the loss of salt ions in the watershed. The continuous arrangement of paddy fields at the bottom of the catchment is an important spatial layout to reduce the loss of farmland salt ions. |
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