soil - Lublin

Table 4.
Methane oxidation efficiency with respect to all examined parameters
Initial methane
concentration
% of methane oxidised
(sample moisture: 50% of a total water capacity)
[%v/v] S1 S2 S3 S4 S5
0.5 100.0 100.0 100.0 21.3 0
1 100.0 100.0 100.0 46.0 0
2 100.0 100.0 100.0 48.4 0
5 100.0 100.0 100.0 44.9 0
10 94.0 72.0 100.0 13.0 0
15 32.8 32.4 19.1 9.5 0
30 1.2 0.1 3.4 0.0 0
Initial methane
concentration
% of methane oxidised
(sample moisture: 100% of a total water capacity)
[%v/v] S1 S2 S3 S4 S5
0.5 100.0 100.0 100.0 100.0 0
1 100.0 100.0 100.0 100.0 0
2 100.0 100.0 100.0 100.0 0
5 100.0 100.0 100.0 100.0 0
10 99.2 92.5 100.0 83.0 0
15 48.1 39.7 47.8 40.7 0
30 1.3 2.1 4.3 7.1 0
Initial methane
concentration
% of methane oxidised
(sample moisture: 200% of a total water capacity)
[%v/v] S1 S2 S3 S4 S5
0.5 100.0 100.0 100.0 100.0 8.9
1 100.0 100.0 100.0 100.0 30.4
2 100.0 100.0 100.0 100.0 23.9
5 100.0 100.0 100.0 100.0 29.2
10 86.8 95.2 99.2 95.2 13.1
15 14.1 9.3 24.0 39.1 9.2
30 1.4 1.3 1.6 14.9 1.6
The amounts of consumed substrate calculated per gram of dry rock in relation
to environmental factors, such as moisture content and initial methane
concentration, are shown in Fig. 2.
The rate of methane oxidation is governed both by the level of initial methane
concentration and by the water content. The maximum of the oxidation rate occurs
at about 10% v/v of methane in the atmosphere at 50% of water content, and
rapidly decreases with higher methane concentrations. Moreover, the oxidation rate
is lower for higher water content levels. Sample moisture content equal to the total
water capacity or twice as high makes the oxidation rate 2-3 fold lower. It is
probably caused by worse diffusion of substrates inside the rock pores and -
therefore - worse availability of substrates for the microorganisms. On the other
hand, this relationship is true for relatively fresh samples, up to 3 years of
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