Temporal and spatial variations in methane cycling in Lake Müggelsee
Archiv für Hydrobiologie Volume 140 Number 2 (1997), p. 195 - 206
published: Sep 25, 1997
ArtNo. ESP141014002009, Price: 29.00 €
Porewater concentration of CH4 and SO42-, the depth distribution of organic matter and the C/N ratio were studied at one profundal and two littoral sites in Lake Müggelsee. CH4 release and oxidation rates were measured using intact sediment cores. The CH4 concentration in profundal sediments varied considerably, with maximum values in winter (470 μmol/l). Conversely, the highest CH4 concentrations in littoral sediments were measured in late summer months (310 μmol/l). The concentrations and calculated diffusive fluxes of SO42- and CH4 were negatively correlated. In profundal sediments, SO42- reduction was the outstanding process in terms of C mineralization and O2 consumption compared to methanogenesis as derived from stoichiometric relations. The gross CH4 release was lowest at profundal sediments (0.8 mmol m-2d-1) and highest at the littoral accumulation site (11.9 mmol m-2d-1). From the ratio of gross and net CH4 release, it can be calculated that 84-91 % of the upward diffusing CH4 will be oxidized at the sediment surface corresponding to CH4 oxidation rates of 0.68 mmol m-2d-1 at profundal sediments and 1.53-10.1 mmol m-2d-1 at littoral sediments. The methanotrophic O2 demand at the sediment surface was of little importance compared to the total O2 consumption with the exception of littoral accumulation zones.