Samarkin et at.: Studies of Methane Production and Emission
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o 1 2 3 4 5 6 7 8 9 10 11 12
methane concentration [mg CH/1000 cm· 3 pore water]
Figure 3b : Methane concentrations in soil pore water, polygon wall, August 1996.
337
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different reactions of methane oxidizing and methane producing bacteria on changing
temperatures: the soil temperatures decreased between end of July and end of August from
about 7-9°C to J-3°C. Moore and Dalva (1993) found out, that methane producing bacteria are
more sensitive on temperature changes than methane consuming bacteria. That explains the
decreasing emission rates at the end of August: less methane was produced, the stored methane
in the soil pore water was emitted to the atmosphere and the rate of methane oxidation was still
high.
Partly, the high methane contents in soil pore water in July also can be explained by the
different behaviour of methanogene and methanotroph bacteria: the soil temperatures increased
and also the methane production - faster than the methane consumption. But after snowmelt the
thickness of the active layer did only increase slowly. It is unlikely that the whole stored
methane was produced during the short time at the beginning of the thawing period in July.
Further, methane may have been produced in the year before at the beginning of the winter
period. At this time, a thin frost layer forestalled gaseous exchange between the soil and the
atmosphere, the soil-gas system was closed from the surface and the bottom. The CH 4 -
gcnerating bacteria still produced CH 4 in the melted layer. Methane oxidation was low because
of low oxygen contents in the soil and strong anaerob conditions. The rhizosphere oxidation of
the died plants was low, too. The formed methane would be trapped in the frozen soil until the
beginning of thawing in the next summer.
Methane contents in pore water were between I-II Ilg CH 4 *ml- i pore water. Svensson and
Rosswall (1984) found 0-20 Ilg CH 4 *ml- i pore water, Williams and Crawford (1984) found 024 Ilg CH 4 *ml- i pore water.
o
10
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~
.r: ....
c.
Ol
""0 20 _
30
(dry surface)
I
I
L
I
I
,
1
1
- - I
1
r -
_ J
I
I
- - - - - - - - - - permafrost-boun ~ary - - - - - - - - - - - -
o 1 2 3 4 5 6 7 8 9 10 11 12
methane concentration [mg CH/1000 cm· 3 pore water]
Figure 3b : Methane concentrations in soil pore water, polygon wall, August 1996.
337
~ :.-lrd !\lJqw:;1
_. 2?rKJ !\U(Just
different reactions of methane oxidizing and methane producing bacteria on changing
temperatures: the soil temperatures decreased between end of July and end of August from
about 7-9°C to J-3°C. Moore and Dalva (1993) found out, that methane producing bacteria are
more sensitive on temperature changes than methane consuming bacteria. That explains the
decreasing emission rates at the end of August: less methane was produced, the stored methane
in the soil pore water was emitted to the atmosphere and the rate of methane oxidation was still
high.
Partly, the high methane contents in soil pore water in July also can be explained by the
different behaviour of methanogene and methanotroph bacteria: the soil temperatures increased
and also the methane production - faster than the methane consumption. But after snowmelt the
thickness of the active layer did only increase slowly. It is unlikely that the whole stored
methane was produced during the short time at the beginning of the thawing period in July.
Further, methane may have been produced in the year before at the beginning of the winter
period. At this time, a thin frost layer forestalled gaseous exchange between the soil and the
atmosphere, the soil-gas system was closed from the surface and the bottom. The CH 4 -
gcnerating bacteria still produced CH 4 in the melted layer. Methane oxidation was low because
of low oxygen contents in the soil and strong anaerob conditions. The rhizosphere oxidation of
the died plants was low, too. The formed methane would be trapped in the frozen soil until the
beginning of thawing in the next summer.
Methane contents in pore water were between I-II Ilg CH 4 *ml- i pore water. Svensson and
Rosswall (1984) found 0-20 Ilg CH 4 *ml- i pore water, Williams and Crawford (1984) found 024 Ilg CH 4 *ml- i pore water.