885
Impacts of Global Warming on Biogeochemical Cycles in Natural Waters
than the mean atmospheric one in the Arctic in summertime, suggesting that
CO 2 might derive from high rates of bacterial respiration (Semiletov et al. 2007).
Ambient partial pressure values of CO 2 (pCO 2 = 21–73.5 Pa) are produced during the coral reef metabolism in Eastern Pacific reef sites. Such values are highly
variable depending on depth, time, space and upwelling-nonupwelling period
(Manzello 2010).
Photoinduced and microbial degradation of DOM and OM is a source of
atmospheric greenhouse gases such as CO 2 and CH 4 , thereby contributing to
global carbon cycle and further global warming (Porcal et al. 2009; Knorr et al.
2005; Davidson and Janssens 2006). Elevated CO 2 enhances DOC supply in peat
soils, an effect that is attributed to elevated net primary productivity and increased
root exudation of DOC. Enhanced DOC in soil will ultimately leach into aquatic
ecosystems (Freeman et al. 2004; Barbiero and Tuchman 2004; Kang et al. 2001;
Pastor et al. 2003; Lavoie et al. 2005; Fenner et al. 2007a, b). Global warming could also increase soil respiration (Freeman et al. 2001, 2004; Tranvik and
Jasson 2002; Evans et al. 2005, 2006; Roulet and Moore 2006; de Wit et al. 2007;
Monteith et al. 2007; Dorodnikov et al. 2011).
Freshwater ecosystems that are presently located across vegetation gradients
will experience significant shifts in underwater spectral irradiance. The main reasons are the effects of climate change on catchment vegetation and the export of
colored DOM (Pienitz and Vincent 2000). Overall, elevated atmospheric CO 2
concentrations would increase primary production, with a consequent increase of
the decomposition of soil OM and an increased export of DOC to nearby natural waters (Porcal et al. 2009). These processes can also contribute to enhance the
DOM contents in natural waters.
4.7 Changes in Nutrients Cycle
The mass balance of nutrients (NO 2
− , NO 3
− , NH 4
+ and total P) is linked
with the major external inputs (terrestrial and atmospheric deposition),
internal sources and transformations (primary and bacterial production,
secondary production, photo- and/or microbial-assimilation of algae or phytoplankton and plant debris), photoinduced transformation of both external and internal sources of nutrients, nitrification, sedimentation and outputs
in natural waters (Mostofa et al. 2009b; Fu et al. 2005; Minero et al. 2007;
Stedmon et al. 2007a, b; Sterner et al. 2008; Ma and Green 2004; Zhang
et al. 2004; Kim et al. 2006; Li et al. 2008; Carrillo et al. 2002; Mallet et al.
1998; Kopác ˇek et al. 1995, 2000, 2004; Lehmann and Bernasconi 2004;
Schindler 1988, 1994; Carlsson et al. 1993; Urabe 1993; Bushaw et al.
1996; Goldman et al. 1996; Ramm and Scheps 1997; Mack and Bolton 1999;
Sterner and Elser 2002; Demott 2003; Xie et al. 2003; Kopác ˇek et al. 2003;
Ahlgren et al. 2005). Coastal waters are generally nutrient-rich whereas open
oceans are often oligotrophic, thus they are usually less productive due to
Impacts of Global Warming on Biogeochemical Cycles in Natural Waters
than the mean atmospheric one in the Arctic in summertime, suggesting that
CO 2 might derive from high rates of bacterial respiration (Semiletov et al. 2007).
Ambient partial pressure values of CO 2 (pCO 2 = 21–73.5 Pa) are produced during the coral reef metabolism in Eastern Pacific reef sites. Such values are highly
variable depending on depth, time, space and upwelling-nonupwelling period
(Manzello 2010).
Photoinduced and microbial degradation of DOM and OM is a source of
atmospheric greenhouse gases such as CO 2 and CH 4 , thereby contributing to
global carbon cycle and further global warming (Porcal et al. 2009; Knorr et al.
2005; Davidson and Janssens 2006). Elevated CO 2 enhances DOC supply in peat
soils, an effect that is attributed to elevated net primary productivity and increased
root exudation of DOC. Enhanced DOC in soil will ultimately leach into aquatic
ecosystems (Freeman et al. 2004; Barbiero and Tuchman 2004; Kang et al. 2001;
Pastor et al. 2003; Lavoie et al. 2005; Fenner et al. 2007a, b). Global warming could also increase soil respiration (Freeman et al. 2001, 2004; Tranvik and
Jasson 2002; Evans et al. 2005, 2006; Roulet and Moore 2006; de Wit et al. 2007;
Monteith et al. 2007; Dorodnikov et al. 2011).
Freshwater ecosystems that are presently located across vegetation gradients
will experience significant shifts in underwater spectral irradiance. The main reasons are the effects of climate change on catchment vegetation and the export of
colored DOM (Pienitz and Vincent 2000). Overall, elevated atmospheric CO 2
concentrations would increase primary production, with a consequent increase of
the decomposition of soil OM and an increased export of DOC to nearby natural waters (Porcal et al. 2009). These processes can also contribute to enhance the
DOM contents in natural waters.
4.7 Changes in Nutrients Cycle
The mass balance of nutrients (NO 2
− , NO 3
− , NH 4
+ and total P) is linked
with the major external inputs (terrestrial and atmospheric deposition),
internal sources and transformations (primary and bacterial production,
secondary production, photo- and/or microbial-assimilation of algae or phytoplankton and plant debris), photoinduced transformation of both external and internal sources of nutrients, nitrification, sedimentation and outputs
in natural waters (Mostofa et al. 2009b; Fu et al. 2005; Minero et al. 2007;
Stedmon et al. 2007a, b; Sterner et al. 2008; Ma and Green 2004; Zhang
et al. 2004; Kim et al. 2006; Li et al. 2008; Carrillo et al. 2002; Mallet et al.
1998; Kopác ˇek et al. 1995, 2000, 2004; Lehmann and Bernasconi 2004;
Schindler 1988, 1994; Carlsson et al. 1993; Urabe 1993; Bushaw et al.
1996; Goldman et al. 1996; Ramm and Scheps 1997; Mack and Bolton 1999;
Sterner and Elser 2002; Demott 2003; Xie et al. 2003; Kopác ˇek et al. 2003;
Ahlgren et al. 2005). Coastal waters are generally nutrient-rich whereas open
oceans are often oligotrophic, thus they are usually less productive due to