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| Parameter estimates of sediment nitrogen mineralization kinetics in the water level fluctuation zone of a Three Gorges Reservoir tributary |
| Received:September 29, 2017 |
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| KeyWord:Three Gorges Reservoir area;nitrogen mineralization rate;water level fluctuation;nitrogen mineralization model;Pengxi River basin |
| Author Name | Affiliation | E-mail | | LIU Dan | Department of Agricultural and Forestry Science and Technology, Chongqing Three Gorges Vocational College, Chongqing 404100, China | | | ZHANG Shuai | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | | | TANG Yu-jiao | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | | | YIN Jing | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | | | TAN Xing-ling | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | | | CHEN Xi | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | | | YU Zhi-guo | College of Hydrometeorology, Nanjing University of Information Science and Technology, Nanjing 210044, China | | | LIN Jun-jie | Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir, Chongqing Three Georges University, Wanzhou 404155, China | ybu_lin@126.com |
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| Abstract: |
| To reveal the effect of drought-rewetting process on the nitrogen mineralization kinetics in the sediment of the water level fluctuation(WLF) zone, surface sediment samples were collected over various water level altitudes at the upper and downstream sections of the Pengxi River. The sediment nitrogen mineralization rate was evaluated with anaerobic incubation. The one-pool, two-pool, special, and effective accumulated temperature models(EATM) were applied to fit the data of nitrogen mineralization kinetics in sediments. The result showed that total organic carbon(C), total nitrogen(N), organic matter(OM), clay, silt, and NH4+-N in the higher altitude were lower than that in the lower altitude, which is on the contrary to total phosphorus, sand, and NO3--N. The one-pool model and special model were the optimal models for fitting nitrogen mineralization in sediments at low and high altitudes, respectively. The N mineralization rate constants(kd) were 0.17 d-1 and 0.12 d-1, while the N mineralization potentials(fd) were 4.05% and 4.71% in the low and high altitude sediments, respectively. The fd was negatively correlated with C, N, C/N ratio, OM, NH4+-N, and silt, and was positively correlated with NO3--N and sand (P<0.05). The kd value had an opposite trend compared to the variation in fd. The model parameters of fd and kd were successfully estimated by using the OM and C/N ratio. The current study revealed that nitrogen mineralization kinetics in sediment had a strong correlation with the water nitrogen content, and could thus be used to predict the contribution of nitrogen input into the WLF zone as an indicator of river eutrophication. |
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