Ferdelman, T. G.. Max-Planck-Institute for marine Microbiology, tferdelm@mpi-bremen.de
Strotmann, B. G.. Max-Planck-Institute for marine Microbiology, bstrotma@mpi-bremen.de
Schubert, C. J.. Max-Planck-Institute for marine Microbiology, cschuber@mpi-bremen.de
Zabel, M. University of Bremen, mzabel@geochemie.uni-bremen.de
Schulz, H. D.. University of Bremen, hdschulz@geochemie.uni-bremen.de

 
ORGANIC CARBON INPUTS AND THE SPATIAL DISTRIBUTION OF SULFATE REDUCTION IN WEST AFRICAN CONTINENTAL SLOPE SEDIMENTS
 
We have investigated the rate of anaerobic remineralization of organic carbon via sulfate reduction in west African continental slope sediments. Sulfate reduction rates (SRR) were measured in a transect of surface sediments (0-30 cm) extending from 3 deg N to 28 deg S along the 1300 m isobath. SRR were also determined at greater depths in selected gravity cores (5 to 20 meter length). In the south, surface SRR were highest (up to 30 nmol cm-3 d-1) and were related to coastal upwelling associated with the Benguela Current. Depth-integrated SRR were estimated to account for nearly one-half of the total rate of organic decomposition. SRR were also strongly correlated with surface organic carbon concentrations in the upwelling dominated sediments. Northwards of the Benguela influence, surface SRR decreased and the correlation with organic carbon weakened. However, SRR measurements in selected gravity cores from the same area, showed that sulfate reduction activity, ostensibly associated with organic carbon remineralization, extended to depths of several meters and may account for up to 30% of the total areal SRR. The impact of terrestrial versus marine organic carbon inputs as controls on SRR are being investigated through the application of biomarkers (i.e. long chain n-alkanes).
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS30TH0366S