Sulfide and methane evolution in the hypolimnion of a subtropical lake: a three-year study |
| |
Authors: | Werner Eckert Ralf Conrad |
| |
Institution: | (1) Israel Limnological and Oceanographic Research, The Yigal Allon Kinneret Limnological Laboratory, P.O. Box 447, Migdal, 14950, Israel;(2) Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., D-35043 Marburg, Germany |
| |
Abstract: | The differential impact of microbial sulfate reduction and methanogenesis on the mineralization of particulate organic carbon
(POC) in warm monomictic Lake Kinneret (LK), Israel was studied during three consecutive lake cycles. The hypolimnetic accumulation
of total sulfide and dissolved methane was examined in relation to the physical forcing of the water column and the settling
flux of particulate matter. With the on-set of thermal stratification in spring, both solutes increased concomitantly with
the depletion of oxygen, first in the benthic boundary layer, followed by the upper hypolimnion. Methane production was restricted
to the sediments as emphasized by the persistently linear concentration gradient in the hypolimnion. Sulfate reduction occurred
both in the sediments and the water column as revealed by the hypolimnetic distribution of sulfide and recurring metalimnetic
sulfide peaks. Annual differences in the accumulation pattern of both solutes appeared to be primarily linked to the settling
flux of POC and the length of the stratified season. Relatively lower hypolimnetic concentrations of dissolved methane during
the stratified season of 2000 coincided with increased ebullition of gaseous methane, likely as the result of a nearly a 2 m
drop in the lake level. Overall, sulfate reduction accounted for more than 60% of the POC settling flux, a finding that differs
from similar studies made in temperate lakes where methanogenesis was shown to be the primary mode of terminal carbon mineralization.
Intensive organic carbon turnover at the sediment water interface and comparatively high sulfate concentrations in LK are
the most likely reason. |
| |
Keywords: | Methane Total sulfide Particulate carbon Hypolimnetic accumulation Lake Kinneret |
本文献已被 SpringerLink 等数据库收录! |
|