Environmental Engineering Reference
In-Depth Information
research avenues for the future. Here, just two areas are mentioned related to the release
of carbon from the massive pools stored in terrestrial ecosystems and implications for
global carbon cycling. First, with climate change affecting both temperature and water
availability there has been a great deal of interest in whether (how) dynamics of soil car-
bon pools might be affected. Overall, there is recognition that carbon mineralization is
almost certain to increase as soils warm, with the most dramatic effects in regions of thaw-
ing permafrost (
Dorrepaal et al. 2009; von Lutzow and Kogel-Knabner 2009
). The precise
mechanism leading to higher respiration and implications for linked element cycles (nitro-
gen in particular) are perhaps less clear and with variable response strengths (
Groffman
et al. 2009; Chapin et al. 2009
), but the fact of significant change seems inevitable.
Second, there are numerous reports that dissolved organic carbon export from terres-
trial ecosystems has recently increased (
Findlay 2005
), and there is good evidence that this
DOC supports heterotrophic metabolism in many surface waters (
Roehm et al. 2009
). The
exact mechanism driving this increase is still uncertain; a response of soils to reduced
acidic deposition has been put forward as one such mechanism (
Evans et al. 2008
). In any
case, this increased flux of carbon must draw down terrestrial storage and represents a
potential for additional CO
2
release during transport in aquatic ecosystems. In essence,
any environmental change, whether small scale or global, has the potential to alter decom-
position of organic matter. Such effects will ramify throughout the ecosystem, affecting
trophic pathways and element cycling.
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