Nitrogen loading and nitrous oxide emissions from a river with multiple hydroelectric reservoirs
Jinsong Chen1, Wenzhi Cao, Di Cao
1State Key Laboratory of Marine Environmental Science, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, South Xiang'an Road, Xiang'an District, Xiamen City, 361102, Fujian Province, China.
Bulletin of Environmental Contamination and Toxicology
|March 28, 2015
Summary
Anthropogenic nitrogen loading significantly impacts nitrous oxide (N2O) emissions from rivers. Dissolved nitrite-nitrogen best predicts N2O concentrations, highlighting key microbial processes in aquatic ecosystems.
Area of Science:
- Environmental Science
- Geochemistry
- Ecology
Background:
- River networks are significant conduits for anthropogenic nitrogen from land to sea.
- The influence of varying nitrogen loads on nitrous oxide (N2O) emissions across diverse riverine ecosystems remains poorly understood.
Purpose of the Study:
- To quantify nitrous oxide (N2O) emissions from different riverine environments.
- To investigate the relationship between nitrogen forms and N2O production in river networks.
- To assess the impact of human activities on N2O emissions.
Main Methods:
- Direct measurement of water-air interface N2O exchange in tributaries, reservoirs, main streams, and estuaries.
- Analysis of dissolved inorganic nitrogen species (nitrite, nitrate, ammonium).
- Statistical analysis to correlate nitrogen concentrations with N2O emissions.
Main Results:
- N2O emissions varied significantly across studied aquatic bodies, with the main stream showing the highest rates.
- Water nitrite-nitrogen concentrations were superior predictors of dissolved N2O compared to nitrate and ammonium.
- Dissolved inorganic nitrogen explained 36% of the variability in N2O emissions across the entire river network.
Conclusions:
- Anthropogenic nitrogen loading strongly influences N2O emissions in river networks.
- Nitrification and denitrification processes, indicated by nitrite levels, are critical drivers of N2O production.
- Understanding nitrogen cycling is crucial for managing greenhouse gas emissions from aquatic ecosystems.
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