A1 Journal article (refereed)
Autochthonous organic matter promotes DNRA and suppresses N2O production in sediments of the coastal Baltic Sea (2021)

Aalto, S. L., Asmala, E., Jilbert, T., & Hietanen, S. (2021). Autochthonous organic matter promotes DNRA and suppresses N2O production in sediments of the coastal Baltic Sea. Estuarine, Coastal and Shelf Science, 255, Article 107369. https://doi.org/10.1016/j.ecss.2021.107369

JYU authors or editors

Publication details

All authors or editorsAalto, Sanni L.; Asmala, Eero; Jilbert, Tom; Hietanen, Susanna

Journal or seriesEstuarine, Coastal and Shelf Science



Publication year2021


Article number107369


Publication countryUnited Kingdom

Publication languageEnglish


Publication open accessNot open

Publication channel open access

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/75207


Coastal environments are nitrogen (N) removal hot spots, which regulate the amount of land-derived N reaching the open sea. However, mixing between freshwater and seawater creates gradients of inorganic N and bioavailable organic matter, which affect N cycling. In this study, we compare nitrate reduction processes between estuary and offshore archipelago environments in the coastal Baltic Sea. Denitrification rates were similar in both environments, despite lower nitrate and carbon concentrations in the offshore archipelago. However, DNRA (dissimilatory nitrate reduction to ammonium) rates were higher at the offshore archipelago stations, with a higher proportion of autochthonous carbon. The production rate and concentrations of the greenhouse gas nitrous oxide (N2O) were higher in the estuary, where nitrate concentrations and allochthonous carbon inputs are higher. These results indicate that the ratio between nitrate and autochthonous organic carbon governs the balance between N-removing denitrification and N-recycling DNRA, as well as the end-product of denitrification. As a result, a significant amount of the N removed in the estuary is released as N2O, while the offshore archipelago areas are characterized by efficient internal recycling of N. Our results challenge the current understanding of the role of these regions as filters of land-to-sea transfer of N.

Keywordsdenitrificationnitrogen fixationcoastal watersdeltasdissolved organic carbonorganic materialsediments

Free keywordsdenitrification; DNRA; DOM; estuary; N2O; sediment organic matter

Contributing organizations

Ministry reportingYes

Reporting Year2021

JUFO rating1

Last updated on 2024-03-04 at 20:16