Riverine nitrous oxide dynamics across China: Scale-dependent patterns and environmental controls
Jiaxin Tian1, Ze Yuan1, Xiaoteng Mao1
1State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, PR China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Journal of Environmental Management
|July 6, 2026
Summary
Chinese rivers are significant sources of nitrous oxide (N₂O), a potent greenhouse gas. Assessing emissions requires considering both dissolved N₂O and water-air exchange, not just concentrations.
Area of Science:
- Environmental Science
- Geochemistry
- Atmospheric Chemistry
Background:
- Nitrous oxide (N₂O) is a potent greenhouse gas and ozone-depleting substance.
- Riverine emissions of N₂O are challenging to quantify across large, complex river networks.
Purpose of the Study:
- To synthesize riverine N₂O observations in China.
- To investigate factors influencing N₂O concentration and flux in rivers.
- To identify limitations of concentration-based assessments for N₂O emission hotspots.
Main Methods:
- Synthesized 2957 riverine N₂O observations from China.
- Integrated site-level water-quality data and basin-scale environmental variables.
- Analyzed associations between N₂O and environmental factors at site and basin scales.
Main Results:
- Chinese rivers are predominantly N₂O sources, with median concentration of 17.5 nmol/L and flux of 10.2 μmol/m²/day.
- N₂O concentration and flux were positively associated but not always proportional.
- Anthropogenic pressure, nutrient, and organic matter conditions significantly influenced N₂O levels, with differing impacts on concentration versus flux.
Conclusions:
- Concentration-based assessments alone are insufficient for identifying riverine N₂O emission hotspots.
- Riverine N₂O inventories must account for both dissolved accumulation and water-air exchange.
- Mitigation strategies should focus on reducing nutrient and organic matter inputs in human-dominated basins.
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