Distribution and emission of N2O in the largest river-reservoir system along the Yellow River
| Autor: | Guan-Xiang Du, Fang Cheng, Gui-Ling Zhang, Guodong Song, Hong-Mei Zhang, Sumei Liu |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Hydrology
Environmental Engineering 010504 meteorology & atmospheric sciences Air pollution Sediment Nitrous oxide 010501 environmental sciences equipment and supplies medicine.disease_cause 01 natural sciences Pollution Atmosphere Bottom water Boundary layer chemistry.chemical_compound chemistry Greenhouse gas medicine Environmental Chemistry Environmental science Waste Management and Disposal Surface water 0105 earth and related environmental sciences |
| Zdroj: | Science of The Total Environment. 666:1209-1219 |
| ISSN: | 0048-9697 |
| DOI: | 10.1016/j.scitotenv.2019.02.277 |
| Popis: | Rivers and reservoirs are affected by human activities and are sources of the greenhouse gas nitrous oxide (N2O). Concentrations of N2O in the middle and lower reaches of the Yellow River and Xiaolangdi Reservoir, China, were measured in June and December 2017. Fluxes were estimated by boundary layer method to explore their controlling factors, especially the impact of damming and reservoir operation. In the middle and lower reaches of the Yellow River, N2O concentrations in surface waters were 26.65 ± 14.67 nmol L−1 in summer and 21.16 ± 5.35 nmol L−1 in winter. In comparison, the concentrations of N2O in the reservoir were 32.94 ± 17.32 nmol L−1 in summer and 23.73 ± 5.60 nmol L−1 in winter. The longitudinal distribution of N2O along the river exhibited different patterns with surface N2O decreasing downstream towards the dam in summer but increasing in winter. Vertical profiles of N2O concentrations in the reservoir showed an increase with depth in summer but were almost vertically uniform in winter. In winter, N2O that had accumulated in the bottom water in summer was transported to the surface by vertical mixing and released into the atmosphere. Dissolved oxygen (DO), water temperature, and in situ biological production were the main factors affecting the distribution of N2O. The mean emissions rates of N2O from the surface waters were 13.7 ± 8.8 μmol m−2 d−1 in summer and 13.2 ± 7.6 μmol m−2 d−1 in winter. Approximately 1.31 × 106 mol N2O was released from the reservoir surface in 2017, which represents 0.12% of the annual N2O emissions from global reservoirs. The construction of dams increased N2O emission from the lower reaches of the river by 4.53 × 105 mol and 1.22 × 105 mol due to the discharge of the bottom water and the water and sediment regulation, respectively. This study demonstrates that the construction of dams and reservoir operation practices have made the Xiaolangdi Reservoir a key area for N2O emissions. |
| Databáze: | OpenAIRE |
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