Studies of fluxes of dissolved iron and manganese in the Gulf of Finland

Metal fluxes (total dissolved iron and manganese) across the water-sediment interface were studied in situ in the Gulf of Finland in June 2002 and 2003 using an autonomous benthic lander. Distribution of these metals in the sediment and the porewater was also investigated. Focus was given to understand the behavior of the studied metals at various redox conditions and the influence when sediment resuspension is occurring. Our data indicate the importance of the redox conditions for the iron fluxes with no fluxes at oxic, intermediate at anoxic and high fluxes at suboxic conditions. The fluxes of manganese do not seem to have any correlation with the oxygen levels. Both metals were significantly affected by resuspension, which led to a rapid release.