Environmental Engineering Reference
In-Depth Information
atmosphere (IPCC
2007a
; van der Werf et al.
2009
). Large-scale deforestation in
the humid tropics has been identified as the main, ongoing land-surface process
caused by industrialization and by growing agricultural activities because of the
increasing demands of a growing population.
3.5 Photoinduced and Microbial Degradation of Organic
Matter (OM) in Natural Waters
The production of CO
2
and of other dissolved inorganic carbon (DIC: generally
defined as dissolved CO
2
, H
2
CO
3
, HCO
3
, and CO
3
2
−
) species upon photoin-
duced and microbial degradation of organic matter including DOM and POM
(e.g. algae or phytoplankton) can potentially influence the carbon cycling and
may have an impact on climate change (Bozec et al.
2005
,
2006
; Schiettecatte
et al.
2006
,
2007
; Borges et al.
2008
; Omar et al.
2010
; Ballaré et al.
2011
;
Zepp et al.
2011
; Kelley
1970
; Kempe and Pegler
1991
; Hoppema
1990
,
1991
;
Borges and Frankignoulle
1999
,
2002a
,
b
; Brasse et al.
1999
; Frankignoulle
and Borges
2001
; Thomas et al.
2004
,
2005
,
2007
; Tranvik et al.
2009
; Xie
et al.
2004
; Salonen and Vähätalo
1994
; Granéli et al.
1998
; Richey et al.
2002
;
Clark et al.
2004
; Kujawinski et al.
2009
; Koprivnjak et al.
2010
). The water-
bed in subtropical and tropical latitudes generally acts as a CO
2
source to the
atmosphere, while at high and temperate latitudes it rather acts as a CO
2
sink
by uptake from the atmosphere (Omar et al.
2010
; Borges and Frankignoulle
2002a
; Thomas et al.
2004
; Sobek et al.
2005
; Gattuso et al.
1993
,
1997
;
Frankignoulle et al.
1996
,
1998
; Goyet et al.
1998
; Tsunogai et al.
1999
; Yool
and Fasham
2000
; Bates et al.
2001
; Cai et al.
2003
,
2006
; Borges
2005
; Ito
et al.
2005
; Ohde and van Woesik
1999
; Wang and Cai
2004
; Chen and Borges
2009
; Wang et al.
2011
). In temperate regions, increased temperatures and
longer residence times of OM in water, which might be caused by decreased
runoff could accelerate microbial respiration and photoinduced degradation of
organic carbon. However, the combined effects of increased autochthonous pro-
duction and increased organic carbon burial efficiency due to increased anoxia
may offset increased CO
2
production (Tranvik et al.
2009
). It should also be
considered that increases in production, duration of stratification and sedimenta-
tion may favor the occurrence of hypolimnetic anoxia and, as a consequence,
CH
4
production in temperate zones (Tranvik et al.
2009
). Larger emissions
of CO
2
and CH
4
may occur in Arctic regions, particularly where thermokarst
erosion and ponding is occurring (Walter et al.
2006
). Moreover some boreal
streams, some major rivers, lakes in general or boreal lakes in particular are
supersaturated in CO
2
and are considered to be net sources of CO
2
to the atmos-
phere (Fahey et al.
2005
; Koprivnjak et al.
2010
; Sobek et al.
2005
; Jones and
Mulholland
1998
; Dawson et al.
2001
; Hope et al.
2001
; Finlay
2003
; Öquist
et al.
2009
; Teodoru et al.
2009
; Cole and Caraco
2001
; Jones et al.
2003c
; Yao
et al.
2007
; Huttunen et al.
2003a
).
−
