Inland waters act as periodic nitrous oxide sinks: The frequency and importance of nitrous oxide undersaturation in freshwater bodies
Abstract
Nitrous oxide (N2O) is a potent and long-lasting greenhouse gas that contributes to ozone depletion. Inland waters are significant, yet highly uncertain, natural sources of N2O to the atmosphere. Aquatic emissions are largely fueled by terrestrial nitrogen inputs that are converted to N2O in the terrestrial-aquatic interface and released via air-water diffusion to the atmosphere. Current N2O emissions estimates assume that N2O production in aquatic systems scales with nitrogen loading. However, recent field-scale studies do not detect relationships between N2O emissions and dissolved nitrogen concentrations, highlighting the need for better understanding of the biogeochemical processes controlling N2O emissions. This work leverages data from 34 aquatic sites in the National Ecological Observatory Network (NEON) to examine controls on dissolved N2O concentrations and N2O emissions from streams, rivers, and lakes across scales and biomes. We find N2O undersaturation is prevalent in the NEON dissolved gas dataset (20-40% of samples) and periodic N2O undersaturation occurs across waterbody types, sizes, and regions. Undersaturation implies that N2O is consumed at a faster rate than atmospheric invasion and the NEON aquatic sites show significant N2O sink behavior associated with periods of undersaturation. We generalize these results by rerunning an existing process-based model (Maavara et al. 2019) and find that the model predicts a similar distribution of N2O undersaturation across inland water types. The model outputs allow us to explore the environmental conditions that support N2O undersaturation, and therefore N2O invasion, in inland waters. These results have implications for our understanding of N2O production in and N2O emissions from inland waters. Maavara, T., R. Lauerwald, G. G. Laruelle, Z. Akbarzadeh, N. J. Bouskill, P. Van Cappellen, and P. Regnier. 2019. Nitrous oxide emissions from inland waters: Are IPCC estimates too high? Glob. Chang. Biol. 25: 473488. doi:10.1111/gcb.14504
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.B35E1480A