Coastal acidification alters estuarine sediment nitrous oxide and methane fluxes

The impact of coastal acidification on sediment nitrous oxide (N2O) and methane (CH4) fluxes is largely unknown. We exposed temperate estuarine sediments to moderate (pH 7.3) and extreme (pH 6.3) acidification. Sediments were collected from two sites-one exposed to high and the other to low nitrogen loading. We demonstrate that low pH has a strong effect on greenhouse gas fluxes. The response, in terms of both magnitude and direction, was site specific. Sediments from the high nitrogen loading site exhibited increased N2O fluxes and decreased CH4 fluxes under moderate and extreme acidification. In contrast, sediments from the low nitrogen loading site exhibited decreased N2O fluxes under moderate and extreme acidification while CH4 fluxes both decreased (moderate) and increased (extreme). This study highlights the dynamic response of sediment N2O and CH4 fluxes to low pH and emphasizes the need for deeper understanding of ofcoastal acidification impacts on sediment biogeochemistry.

Automated summary

The impact of coastal acidification on sediment N2O and CH4 fluxes is still unclear. This study exposed temperate estuarine sediments to moderate and extreme acidification and found that low pH had a strong effect on greenhouse gas fluxes, but the response varied depending on the site and nitrogen loading. Sediments from high-nitrogen loading site showed increased N2O fluxes and decreased CH4 fluxes under acidification, while sediments from low-nitrogen loading site exhibited decreased N2O fluxes and both decreased and increased CH4 fluxes. This study highlights the dynamic response of sediment N2O and CH4 fluxes to low pH and emphasizes the need for a deeper understanding of coastal acidification impacts on sediment biogeochemistry.