UNEP/GRID-Arendal and Landsat 2000
Activity and Diversity of Methanogens and Methanotrophs Under Extreme Environmental Conditions in Permafrost Soils
D. Wagner, S. Liebner and S. Kobabe
Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
ARC 915 + DAPI ARC 915 + DAPI
ARC 915 + EUB 338 mix ARC 915 + EUB 338 mix
Permafrost soils of high-latitude wetlands are an important source of atmospheric methane. More than 14 % of the world`s soil carbon is preserved in permafrost. Microbial life in these habitats, which are completely frozen most time of the year, is influenced by extreme environmental conditions. In order to improve our understanding of the carbon dynamic in permafrost soils, we studied the CH4fluxes as well as the function and diversity of the fundamental processes of CH4 production and CH4oxidation in a typical polygonal tundra of the Lena Delta, Siberia.
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NTRODUCTIONNTRODUCTIONS
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TUDY TUDYS S
ITEITEThe field investigations were carried out on the island Samoylov located in the Lena Delta, Siberia, which represented an area of typical polygonal tundra. The peaty soils of the polygon depression (Typic Historthel) are characterized by a water level near the soil surface and the predominantly anaerobic accumulation of organic matter. The drier soil of the polygon rim (Glacic Aquiturbel) show a distinctly deeper water level and lower accumulation of organic matter. The average air temperature was -14.7 °C with a min. of -47.8 °C in January and a max.
of +18.3 °C in July.
Cross section of a typical ice-wedge polygon (Lena Delta, Siberia)
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ONCLUSIONONCLUSIONcontact: dwagner@awi-potsdam.de Study site on Samoylov
Island located in the Lena Delta, Siberia.
The results indicated the existence of a permafrost microbiota, which has well adapted to the extreme environmental conditions. The knowledge of the activity, physiology and ecology of the microbial community is fundamental for understanding trace gas fluxes in the Arctic. In outlook, this approach provides the basis for future environmental studies that deal with the fate of carbon stored in permafrost in the course of climate changes.
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Vertical profile of Archaea, Eubacteria and total cell counts in the active layer detected by FISH and DTAF-staining.
Aggregates of methanogenic archaea in permafrost soils detected by fluorescence in situhybridisation. The aggregate formation could serve as protection against extreme habitat conditions.
CH4production at sub-zero tempera-tures with H2/CO2as a substrate.
0 100 200 300 400 500
0 500 1000 1500 2000 2500 3000 0 150 300 450 600 750 900
- 3 °C
CH4
time [h]
- 6 °C
CH4
CH4[ppm]CH4[ppm]
ice wedge
polygon depression (Typic Historthel) polygon rim (Glacic
Aquiturbel)
N 72 N 72°°22`22`
E 126 E 126°°29`29`
Lena Delta polygonal tundra
Samoylov Island
cell numbers 108g-1
depth[cm]
40 30 20 10 0
0 2 4 6 8 10 12 14 16 18 20 22 24 polygon depression ARC915 EUBmix DTAF
CH4oxidation rates at 0, 4, 10 and 21°C and the distribution of Type I and Type II methanotrophs within the active layer of a permafrost soil.
60 50 40 30 20 10 0
0 10 20 30 40 50 60
CH4oxidation rate [nmol h-1g-1]
depth[cm] 0°C4°C
10°C 21°C
Type I Type I
Type I Ai Ah Gr1
Gr2
P Type I
Type IType II
(Type I) Gr3 Gr4
Type IType II
frozen ground
horizon FISH
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CTIVITY AND CTIVITY ANDD D
IVERSITYIVERSITYThe CH4 production and oxidation under in situ conditions revealed great differences during the vegetation period . Even the incubation of soil material at sub-zero temperatures showed a significant CH4 production . Oxidation experiments at temperatures between 0°C and 21°C indicated the highest CH4oxidation in the bottom of the active layer at 4 °C . DTAF-staining and FISH showed a decrease of total cell counts from the top to the bottom of the active layer and large variation of the microbial community in different horizons . Within the constantly cold horizons of the active layer an aggregate formation of archaea could be regularly observed .
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Vertical profile of CH4production and in situ temperature. CH4production rate and soil temperature determined (a) in July 1999 and (b) in August 1999.
30 25 20 15 10 5 0
0 2 4 6 8 10 0 2 4 6 8 10
depth[cm]
CH4
0 2 4 6 8 10
temperature temperature [°C]
CH4oxidation rate [nmol h-1g-1]
0 2 4 6 8 10
frozen ground
polygon depression
a. b.
Vertical profile of CH4oxidation and in situ temperature. CH4oxidation rate and soil temperature determined (a) in July 1999 and (b) in August 1999.
30 25 20 15 10 5 0
0 2 4 6 8 38 40 42 0 2 4 6 8 38 40 42 CH4production rate [nmol h-1g-1]
depth[cm]
0 2 4 6 8 10
CH4
0 2 4 6 8 10
temperature temperature [°C]
polygon depression frozen ground
a. b.
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