SS2.02 Biogeochemical Process at the Sediment-Water Interfaces
Date: Tuesday, June 11, 2002
Time: 11:45:00 AM
Location: Carson B
 
TANKERESP, University of Bergen, Bergen, Norway, sophie.muller@im.uib.no
Muller, F, L, University of Bergen, Bergen, Norway, francois.muller@kj.uib.no
Torsvik, V, , University of Bergen, Bergen, Norway, vigdis.torsvik@im.uib.no
 
HIGH SPATIAL RESOLUTION OF REDOX MICROENVIRONMENTS AND MICROBIAL COMMUNITY STRUCTURE IN THE UPPERMOST SEDIMENTS OF A MEROMICTIC LAKE IN NORWAY.
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An assessment of microbiological diversity using molecular techniques was carried out in combination with chemical measurements (O2, Mn2+, Fe2+, H2S, pH, redox potential) at the sediment-water interface of a coastal lagoon. pH showed a maximum just above the sediment-water interface coinciding with an oxygen maximum suggesting photosynthetic activity by Cyanobacteria, and a minimum coinciding with the O2-H2S interface which is consistent with the presence of sulfur chemolitotrophs. The redox potential was high in bottom water and surface sediment reflecting the presence of oxygen and oxides and reached low values after a step-wise decrease at -18 mm. Reduction of Fe oxides occurred within the biofilm at the O2-H2S interface and was mostly due to reduction by H2S. High concentrations of dissolved Mn in oxic water may have been caused either by in situ production within organic aggregates or by lateral water flow from sites nearby where Mn2+ diffuses from sediment. Although the resolution of techniques used were different, sequencing results were consistent with chemical data in delineating the same horizons according to redox, pH or ecological properties.