Distribution of methane in the Lena Delta and Buor-Khaya Bay, Russia Alfred Wegener Institute for Polar and Marine Research, Marine Station Helgoland, Kupromenade 201, 27498 Helgoland, Germany
11 Jul 2013
Received: 01 Oct 2012 – Published in Biogeosciences Discuss.: 15 Nov 2012Abstract. The Lena River is one of the largest Russian rivers draining into the Laptev
Sea. The permafrost areas surrounding the Lena are predicted to thaw at
increasing rates due to global temperature increases. With this thawing,
large amounts of carbon – either organic or in the gaseous forms carbon
dioxide and methane – will reach the waters of the Lena and the adjacent
Buor-Khaya Bay (Laptev Sea). Methane concentrations and the isotopic signal
of methane in the waters of the Lena Delta and estuary were monitored from
2008 to 2010. Creeks draining from permafrost soils produced hotspots for
methane input into the river system (median concentration 1500 nM) compared
with concentrations of 30–85 nM observed in the main channels of the Lena.
No microbial methane oxidation could be detected; thus diffusion is the main
process of methane removal. We estimated that the riverine diffusive methane
flux is 3–10 times higher than the flux from surrounding terrestrial
environment. To maintain the observed methane concentrations in the river,
additional methane sources are necessary. The methane-rich creeks could be
responsible for this input.
Revised: 30 Apr 2013 – Accepted: 07 May 2013 – Published: 11 Jul 2013
In the estuary of Buor-Khaya Bay, methane concentrations decreased to
26–33 nM. However, within the bay no consistent temporal and spatial
pattern could be observed. The methane-rich waters of the river were not
diluted with marine water because of a strong stratification of the water
column. Thus, methane is released from the estuary and from the river mainly
by diffusion into the atmosphere.
Citation: Bussmann, I.: Distribution of methane in the Lena Delta and Buor-Khaya Bay, Russia, Biogeosciences, 10, 4641-4652, doi:10.5194/bg-10-4641-2013, 2013.