Ho, T. MSRC SUNY at Stony Brook, hty@pro.msrc.sunysb.edu
Scranton, M. MSRC SUNY at Stony Brook, mscranton@notes.sunysb.edu
Taylor, G. T. MSRC SUNY at Stony Brook, gtaylor@notes.cc.sunysb.edu
Iabichella, M. MSRC SUNY at Stony Brook, miabichel@ccmail.sunysb.edu

 
THE IMPORTANCE OF MANGANESE CYCLING FOR ORGANIC CARBON DECOMPOSITION IN THE WATER COLUMN OF THE CARIACO BASIN
 
As a part of the CARIACO program, we measured the dissolved and total Mn concentration, and the acetate uptake rates (respiration plus incorporation) in the water column of the Cariaco Basin. Maximum dissolved Mn++ concentrations and maximum acetate uptake rate occurred at the same depth. This depth, which is coincident with the first appearance of H2S, was 260 m in May 1997, but shifted to 350 m for Nov. 97 and Mar. 98. Total bacterial abundance also followed the same pattern. Inhibition experiments showed that molybdate did not significantly inhibit acetate uptake, but that azide blocked 90 to 100% of the uptake of acetate in the anoxic portion of the Cariaco Basin. Mn reduction rate was estimated, as diffusive flux, from the concentration gradient across the oxic/anoxic interface and estimates of the diffusion coefficient. These calculation suggest that Mn reduction can account for 10-30% of the acetate uptake near the acetate uptake maximum. Our data suggest that Mn reduction rather than sulfate reduction may be the dominant pathway of organic matter decomposition in the anoxic water column of the Cariaco Basin.
 
Day: Wednesday, Feb. 3
Time: 09:00 - 09:15am
Location: Hilton of Santa Fe
 
Code: SS38WE0900H