ABSTRACT
Trace Gases ...................................................................................... 264
10.3 Importance of a Trace Gas, CH
, for the Life Cycle
of Specific Microbial Populations in Soil ....................................... 267
10.4 Relevance of the Microbial Community Structure
for Trace Gas Cycling...................................................................... 272
10.4.1 Methanotrophic Communities ............................................ 273
10.4.2 Methanogenic Communities............................................... 275
10.5 Influence of Global Climate Change on Soil
Microbial Communities ................................................................... 276
Acknowledgments ....................................................................................... 278
References ................................................................................................... 278
Dramatic changes in the composition of the atmosphere have occurred during
Earth’s history, including the transition from anoxic to oxic conditions, but
also changes in the abundance of greenhouse gases. Presently, we are
experiencing an increase in the abundance of greenhouse gases, which is to
a significant extent of anthropogenic origin. This began approximately in the
19th century, and is still continuing [1]. The major greenhouse gases of
anthropogenic origin are carbon dioxide (CO
), methane (CH
), nitrous oxide
(N
O) and halocarbons, which are released into the atmosphere by the burning
of fossil fuel and biomass, as well as other activities in industry and
agriculture. Methane and N
O are produced mainly by microorganisms that
are stimulated by human activities such as the increased use of fertilizer, cattle
production, soil water management and waste management. Microorganisms
are also involved in the cycling of other trace gases, such as carbon monoxide
(CO), hydrogen (H
), nitric oxide (NO) and reduced sulfur species, which
affect the chemistry of the atmosphere and, thus, indirectly also affect the
radiation balance of Earth [2]. Hence, microorganisms are a key component in
the cycling of greenhouse gases. Human activity thus only indirectly causes
global climate change, i.e. human activity affects microbial communities,
which in turn affect the composition of the atmosphere. Global climate change
will not be understood without proper knowledge of what the relevant
microorganisms do and how they react.
