Significant Seasonal N₂O Dynamics Revealed by Multi‐Year Observations in the Northern South China Sea

Abstract

and they are challenging to constrain because both excess N 2 O (ΔN 2 O) and the transfer velocity (k) are regulated by multiple environmental factors such as temperature, salinity, N 2 O concentration, wind speed, and boundary layer dynamics (Wanninkhof et al., 2009). Consequently, quantitative estimates of N 2 O fluxes are highly uncertain and inconsistent among studies (

Mixed Archaeal Production and Nitrifier Denitrification Dominate N2O Production in the East China Sea: Insights From Isotopocule and Hydroxylamine Analyses

“…The slopes of ΔN 2 O versus AOU in shallow water (0.05, Figure 6) were concordant with previous results (0.02-0.12) in the ECS (Chen et al, 2021;Wang et al, 2016;Zhang et al, 2010). Globally, our results fell within the reported range of 0.01-0.30 (Nevison et al, 2003;Wan et al, 2022). Based on the slope of AOU versus ΔN 2 O and the Redfield ratios, which attribute ∼17% of AOU to ammonia oxidation (Ward, 2008), we estimated that the N 2 O yield from nitrification-linked processes, namely, the fraction of nitrification-derived N 2 O to NH 4 + consumed, was 0.03% in shallow water.…”

A Synthesis of Global Coastal Ocean Greenhouse Gas Fluxes

“…While coastal ocean waters are a sink of CO 2 , they are also the main oceanic source of two other important greenhouse gases: nitrous oxide (N 2 O) and methane (CH 4 ) (e.g., Saunois et al., 2020; Wan et al., 2022; Weber et al., 2019; Yang et al., 2020). RECCAP did not consider N 2 O and CH 4 , but recent studies have compiled oceanic N 2 O and CH 4 measurements (Kock & Bange, 2015) and applied statistical gap‐filling techniques similar to those employed for CO 2 to assess the global ocean air‐sea N 2 O and CH 4 fluxes (Weber et al., 2019; Yang et al., 2020).…”

“…Coastal upwelling regions, such as the nearshore California Current, are sources of CO 2 to the atmosphere with a marked seasonality that follows the upwelling dynamics (Dai et al., 2013; Damien et al., 2023; Fiechter et al., 2014; Lachkar & Gruber, 2013; Turi et al., 2014). Tropical systems, such as the Gulf of Mexico (Laurent et al., 2017; Xue et al., 2016) and the South China Sea (Wan et al., 2022), are mostly identified as weak CO 2 sources with weak seasonal variability (Dai et al., 2022; Laruelle et al., 2014, 2015; Roobaert et al., 2019). Our knowledge of N 2 O and CH 4 variability in the global coastal ocean is more limited, but gap‐filled products and global models suggest that N 2 O and CH 4 annual emissions strongly vary between coastal regions (e.g., Ganesan et al., 2020; Stell et al., 2022; Weber et al., 2019; Yang et al., 2020).…”

Long-term multi-meta-omics resolves the ecophysiological controls of seasonal N2O emissions

“…Most WWTPs emit the majority of their yearly N2O during a winter or spring peak lasting 3-4 months, with simultaneous NO2accumulation 17,[21][22][23][24]26 (Table S1). Similarly, higher N2O emissions during colder seasons are widely reported for oceans 10 , soils 12,13 , and lakes 14 . Low or increasing temperatures have been hypothesized as the underlying causes for the seasonal N2O emissions, but a clear correlation is often missing 10,13,14,18,19,27,28 .…”

“…1A). Seemingly ubiquitous is the strong seasonality of N2O emissions in many natural and managed environments, such as oceans 9,10 , soils [11][12][13] , lakes 14,15 and rivers 16 , and engineered systems such as wastewater treatment plants [17][18][19][20][21][22][23][24] (WWTPs, summarized in Table S1). This indicates that seasonally-impacted macroscopic factors directly influence biological N2O turnover.…”