Seasonal decoupling of sulfate reduction and the anaerobic oxidation of methane in Mono Lake, California.
Abstract
Mono Lake is an alkaline, hypersaline, meromictic lake. We documented seasonal variability in geochemical parameters and in rates sulfate reduction (SR) and the anaerobic oxidation of methane (AOM). We used standard geochemical methods to quantify concentrations of redox variables and radiotracer (S-35, C-14) techniques to determine rates of AOM and SR over depth and. Mono Lake water has elevated concentrations of sulfate and DOC and bottom waters are enriched in reduced metabolites, such as methane, hydrogen sulfide and ammonium, relative to surface waters. Seasonal shifts in geochemical zonation and in rates of SR and AOM were related to biological and physical forcing factors. Rates of AOM were extremely high rates (up to 1 μM/day) during winter and summer but were lower during the spring and fall. During summer, SR rates were similar to AOM rates (about 2 μM/day). Following the fall phytoplankton bloom, SR rates were ten times higher while AOM rates decreased. This temporal decoupling of SR and AOM processes appears to result from the delivery of bloom derived (presumably labile) organic carbon to bottom waters.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....13314J