Geoscience Reference
In-Depth Information
with present knowledge, only
first steps are possible in modeling all these features
of the global cycle of CH
4
.
The sources of methane are oil, sedimentary and ejected rocks, bottom sediments
of lakes, seas, oceans, and other objects of the hydrosphere, as well as soil, peat-
bogs, rice plantations, and others:
natural gas and oil extracting and re
ning systems;
vital functions of animals;
heaps of solid waste;
coal mines functioning;
processing of stock-breeding waste;
sewage processing;
anaerobic decomposition of organic matter in
fl
flooded rice
fields;
fossil fuel burning at stationary and mobile systems;
burning of agricultural waste, biomass, rubbish, and
fires in savannahs; and
various industrial processes.
The basic reaction of methane formation due to anaerobic fermentation or
mineralization of organic matter is as follows:
C
6
H
12
O
6
!
3CO
2
þ
3CH
4
:
Sinks for tropospheric methane are:
reaction with hydroxyl radical (
90 %);
*
transport to the stratosphere (
5 %); and
*
oxidation in dry soil (
5 %).
*
Ways of methane transformation, as shown in Table
1.13
, include numerous
processes by 70
80 % of biogenic origin mostly affected by humans. Of course, the
-
signi
cance of these processes varies depending on many natural and anthropo-
genic parameters. Relationships of individual elements of correlation between the
cycles of CO
2
,CH
4
, and other chemicals vary, too. At any rate, it is clear that
depending on the strategy adopted for the nature-society system, in due course the
composition of the terrestrial atmosphere will change substantially. Suf
ce it to say
that only burning of 1 m
3
of methane extracts from the atmosphere 2 m
3
O
2
. From
the open dust-heaps and municipal and industrial sewage, the atmosphere receives
annually about 2 % of anthropogenic methane (
10
6
t C). These
integral estimates do not permit one to calculate an actual distribution of CH
4
fl
*
270
-
460
×
ux
in the atmosphere.
A certain contribution to detailing of the spatial distribution of the sources of
methane was made at the Second International Conference on the problems of
methane held in Novosibirsk in 2000. Proceedings of this Conference contain
concrete data on the sources of methane in many regions of the globe. For instance,
according to Byakola (2000), within the framework of the international UNEP/GDP
project, an inventory of the sources and sinks of CO
2
and CH
4
has been made for
the territory of Uganda (236
10
3
km
2
). In Uganda, basic anthropogenic sources of
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