Seasonal oxygen, nitrogen and phosphorus benthic cycling along an impacted Baltic Sea estuary: regulation and spatial patterns
Number of Authors: 5
2014 (English)In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 119, no 1-3, 139-160 p.Article in journal (Refereed) Published
The regulatory roles of temperature, eutrophication and oxygen availability on benthic nitrogen (N) cycling and the stoichiometry of regenerated nitrogen and phosphorus (P) were explored along a Baltic Sea estuary affected by treated sewage discharge. Rates of sediment denitrification, anammox, dissimilatory nitrate reduction to ammonium (DNRA), nutrient exchange, oxygen (O2) uptake and penetration were measured seasonally. Sediments not affected by the nutrient plume released by the sewage treatment plant (STP) showed a strong seasonality in rates of O2 uptake and coupled nitrification-denitrification, with anammox never accounting for more than 20% of the total dinitrogen (N2) production. N cycling in sediments close to the STP was highly dependent on oxygen availability, which masked temperature-related effects. These sediments switched from low N loss and high ammonium (NH4+) efflux under hypoxic conditions in the fall, to a major N loss system in the winter when the sediment surface was oxidized. In the fall DNRA outcompeted denitrification as the main nitrate (NO3-) reduction pathway, resulting in N recycling and potential spreading of eutrophication. A comparison with historical records of nutrient discharge and denitrification indicated that the total N loss in the estuary has been tightly coupled to the total amount of nutrient discharge from the STP. Changes in dissolved inorganic nitrogen (DIN) released from the STP agreed well with variations in sedimentary N2 removal. This indicates that denitrification and anammox efficiently counterbalance N loading in the estuary across the range of historical and present-day anthropogenic nutrient discharge. Overall low N/P ratios of the regenerated nutrient fluxes impose strong N limitation for the pelagic system and generate a high potential for nuisance cyanobacterial blooms.
Place, publisher, year, edition, pages
2014. Vol. 119, no 1-3, 139-160 p.
Sediment, Benthic flux, Denitrification, Anammox, DNRA, Eutrophication
Earth and Related Environmental Sciences
Research subject Geochemistry
IdentifiersURN: urn:nbn:se:su:diva-97297DOI: 10.1007/s10533-014-9953-6ISI: 000336028400010OAI: oai:DiVA.org:su-97297DiVA: diva2:676596
ProjectsBaltic NutrientsBaltic Ecosystem Adaptive Management - BEAMStockholm University Marine research Centre
FunderEcosystem Approach to the Baltic Sea (Upphört/Closed 2010)Swedish Research Council Formas