AUTHOR=Foster Sarah Q. , Fulweiler Robinson W. 

TITLE=Sediment Nitrous Oxide Fluxes Are Dominated by Uptake in a Temperate Estuary

JOURNAL=Frontiers in Marine Science

VOLUME=3

YEAR=2016

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2016.00040

DOI=10.3389/fmars.2016.00040

ISSN=2296-7745

ABSTRACT=<p>Coastal marine ecosystems are generally considered important sources of nitrous oxide (N<sub>2</sub>O), a powerful greenhouse gas and ozone depleting substance. To date most studies have focused on the environmental factors controlling N<sub>2</sub>O production although N<sub>2</sub>O uptake has been observed in a variety of coastal ecosystems. In this study, we examined sediment fluxes of N<sub>2</sub>O during 2 years (2012–2013) in a shallow temperate estuary (Waquoit Bay, MA, USA). Overall sediments were a net N<sub>2</sub>O sink (–23 ± 5.2 nmol m<sup>−2</sup> h<sup>−1</sup>, mean ± <italic>SE</italic>, significantly less than zero <italic>p</italic> &lt; 0.0001). N<sub>2</sub>O fluxes were significantly correlated to water column dissolved N<sub>2</sub>O (% saturation; <italic>p</italic> &lt; 0.0001), inorganic phosphorus (DIP; <italic>p</italic> = 0.0017), and nitrogen (DIN; <italic>p</italic> = 0.0019), as well as to temperature (<italic>p</italic> = 0.0192). Additionally, there was a positive correlation between sediment N<sub>2</sub>O uptake and both oxygen (O<sub>2</sub>) and DIP uptake (<italic>p</italic> = 0.0002 and <italic>p</italic> &lt; 0.0001, O<sub>2</sub> and DIP sediment uptake, respectively). Results from this study indicate that sediments in shallow coastal ecosystems can be a strong sink of dissolved N<sub>2</sub>O, and therefore may mitigate N<sub>2</sub>O efflux to the atmosphere and export to the coastal ocean. Establishing the nature and strength of relationships between environmental conditions and sediment N<sub>2</sub>O fluxes moves us toward better-constrained models that will improve ecosystem management strategies, N<sub>2</sub>O budgets, and our ability to predict the response of coastal ecosystems to local and global change.</p>