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Pervasive nitrous oxide undersaturation in U.S. lakes and reservoirs
Citation:
Beaulieu, J., R. Martin, AND M. McManus. Pervasive nitrous oxide undersaturation in U.S. lakes and reservoirs. Nature Communications. Nature Portfolio, Berlin, Germany, 17:8551, (2026). https://doi.org/10.1038/s41467-026-74705-6
Impact/Purpose:
Excessive nitrogen loading to surface waters can stimulate the production of nitrous oxide, a contributor to stratospheric ozone destruction, and it is generally believed that surface waters are a globally significant source of N2O to the atmosphere. This study found that most US lakes and reservoirs function as a sink for nitrous oxide rather than a source. This finding suggests that the role of surface waters in the global N2O budget may be overestimated.
Description:
Lakes and reservoirs are estimated to be globally important sources of nitrous oxide (N2O) to the atmosphere but recent evidence of N2O uptake across a broad range of lakes have called the accuracy of emission estimates into question. Here, we use a new national-scale dataset of dissolved N2O concentration and a Bayesian hierarchical model to predict summertime N2O concentration and emission rates in 465,896 waterbodies in the conterminous U.S. (CONUS). We found that N2O undersaturation was pervasive throughout the CONUS during the summer of 2017, with an estimated 72.9% (95% credible interval: 68.9–76.6%) of lakes functioning as N2O sinks. The model predicts dissolved N2O concentrations reasonably well based partly on interactions between nitrate concentration, waterbody surface area, and water temperature. Despite working with the largest aquatic N2O dataset to date, our national-scale estimate of summertime N2O emissions from CONUS lakes is poorly constrained, with a 95% credible interval ranging from net uptake to net emission (−282 − 482 metric tons N2O summer−1). Pervasive N2O undersaturation in CONUS waterbodies during the summer highlights the need to revisit N2O models which presume surface waters are a N2O source.
URLs/Downloads:
DOI: Pervasive nitrous oxide undersaturation in U.S. lakes and reservoirs
https://pubmed.ncbi.nlm.nih.gov/42436135/