Inland Waters can Act as Nitrous Oxide Sinks: Observation and Modeling Reveal that Nitrous Oxide Undersaturation May Partially Offset Emissions
Kelly S. Aho, Taylor Maavara, K. M. Cawley, Peter A. Raymond
Abstract
Abstract Inland waters are significant, yet highly uncertain, natural sources of nitrous oxide (N 2 O). Many emission models assume that N 2 O is only emitted from freshwaters, and that N 2 O sink behavior is negligible. However, observational studies have reported N 2 O undersaturation, suggesting that inland waters can act as N 2 O sinks due to net N 2 O consumption. This study leverages data from the National Ecological Observatory Network (NEON) and an existing global emission model to examine the prevalence of and controls on N 2 O undersaturation in streams, rivers, and lakes across scales and biomes. We find that N 2 O undersaturation is prevalent in the NEON data set (14%–30% of samples) and process‐based model outputs (38%), occurring across biomes and spatial scales. Failing to account for undersaturation in the NEON data set could result in an 100% overestimation of N 2 O emissions. These results show that consideration of N 2 O sink behavior is needed for accurate emission estimates.