Effects of oxygen on recycling of biogenic elements from sediments of a stratified coastal Baltic Sea basin
Artikel i vetenskaplig tidskrift, 2016
Benthic nutrient dynamics in the coastal basin Kanholmsfjärden, NW Baltic proper, were studied by in situ
flux measurements and sediment samplings in 2010–2013. The benthic release of NH4 and DIP from anoxic
sediments in Kanholmsfjärden were calculated to renew the standing stock inventories of DIN and DIP in the
overlying water in roughly 1 year.
Starting in summer 2012, mixing of oxygen-rich water into the deep part of the basin temporarily improved the
oxygen conditions in the deepwater. During the 1 year oxygenated period, the total phosphorus inventory in the
surficial sediment increased by 0.4 g Pm−2 or 65%. Thiswasmost likely due to stimulated bacterial P assimilation
under oxygenated conditions.
By July 2013, the bottomwater had again turned anoxic, and DIP and DSi fluxes were even higher than earlier in
the study period. These high fluxes are attributed to degradation of sedimentary pools of P and Si that had accumulated
during the bottom water oxygenation in 2012. The strong correlation between DIP and DSi fluxes and
the similar dynamics of DIP and DSi in the sediment pore water and near bottom water, suggest a similar
redox dependency of benthic–pelagic exchange for these nutrients.
© 2015 The Authors. Published by Elsevier B.V. This is an open
Baltic Sea Benthic nutrient flux Bottom water oxygenation Sediment chemistry