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Continuous Seasonal River Ebullition Measurements Linked to Sediment Methane Formation
journal contribution
posted on 2015-11-17, 00:00 authored by Jeremy Wilkinson, Andreas Maeck, Zeyad Alshboul, Andreas LorkeLaboratory sediment incubations and
continuous ebullition monitoring
over an annual cycle in the temperate Saar River, Germany confirm
that impounded river zones can produce and emit methane at high rates
(7 to 30 (g CH4 m–3 d–1) at 25 °C and 270 to 700 (g CH4 m–2 yr–1), respectively). Summer methane ebullition
(ME) peaks were a factor of 4 to 10 times the winter minima, and sediment
methane formation was dominated by the upper sediment (depths of 0.14
to 0.2 m). The key driver of the seasonal ME dynamics was temperature.
An empirical model relating methane formation to temperature and sediment
depth, derived from the laboratory incubations, reproduced the measured
daily ebullition from winter to midsummer, although late summer and
autumn simulated ME exceeded the observed ME. A possible explanation
for this was substrate limitation. We recommend measurements of methanogenically
available carbon sources to identify substrate limitation and help
characterize variation in methane formation with depth and from site
to site.