Environmental Engineering Reference
In-Depth Information
nutrient limitation (Kolber et al. 1990 ; Shen 2001 ; Falkowski et al. 2004 ; Ho
et al. 2008 ). Nutrient enrichment is a common feature in lakes, estuaries and
coastal oceans worldwide, which can be the primary cause of eutrophication
from excess algal growth (Yoshiyama and Sharp 2006 ; Smith 2003 ). Large
amounts of nutrients (NO 3
and total P or PO 4 3 ) are produced from
photoinduced and microbial-assimilations of algae or phytoplankton biomass, as
well as by photoinduced degradation of DOM in natural waters (Stedmon et al.
2007a , b ; Fu et al. 2010 ; Kim et al. 2006 ; Li et al. 2008 ; Kopácˇ ek et al. 2004 ;
Kopácˇ ek et al. 2003 ). Formation of N-containing (NH 4
+
, NH 4
+
) and
P-containing inorganic compounds (PO 4 3 ) may take place upon degradation of
dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in
the epilimnion of natural waters (Mostofa et al. 2011 ; Zhang et al. 2004 ; Kim
et al. 2006 ; Li et al. 2008 ; Bronk 2002 ; Vähätalo and Järvinen 2007 ). DIC is
also produced both photolytically and microbially from DOM in natural waters
(Granéli et al. 1996 ; Ma and Green 2004 ; Miller and Moran 1997 ; Bertilsson and
Tranvik 2000 ). Seasonal and long-term variations of N-containing compounds in
natural waters are influenced by biological processes, in which uptake by algae or
phytoplankton and denitrification in bottom water play a major role (Seitzinger et
al. 2006 ). It is therefore suggested that algae or phytoplankton might be the key
controlling factors that determine the total content of nutrients in natural waters.
Global warming could cause a loop by significantly increasing the photoinduced
degradation of DOM with high production of photoproducts (e.g. CO 2 , DIC, H 2 O 2 ),
which can enhance photosynthesis and primary production. The effect is a higher
production of nutrients, particularly in waters with high DOM contents. Therefore,
global warming could lead to a considerable eutrophication of already DOM-rich
waters.
The nutrients from external inputs (terrestrial and atmospheric deposition) and
sedimentation sources are expected to play a less important role toward primary
production. Indeed, high contents of nutrients are observed in waters with high
contents of DOM or chlorophyll a (Stedmon et al. 2007a , b ; Fu et al. 2010 ; Li
et al. 2008 ; Carrillo et al. 2002 ; Kopá ˇek et al. 2000 , 2004 ). At the same time,
N-compounds are strongly dependent on climatic factors in natural waters
(Mitchell et al. 1996 ; Murdoch et al. 1998 ; Weyhenmeyer 2008 ; Hessen et al.
2009 ). An increase in temperature and changes in the precipitation regime can
affect biological processes in soil and water, which are involved into the retention
and release of N (Windolf et al. 1996 ; Khalili and Weyhenmeyer 2009 ). On the
other hand, waters with low contents of either DOM or chlorophyll a often show
low contents of nutrients that typically remain the same for long periods (Kim
et al. 2006 ; Goldman et al. 1996 ; Fott et al. 1994 ; Vyhnálek et al. 1994 ; Sugiyama
et al. 2005 ). These processes are affected by water temperature, thus climate
parameters may exert a major control on nutrient variability in natural waters.
Global warming could thus modify the seasonal patterns of nutrient concentra-
tions in the water column of lakes and oceans (Letelier et al. 2004 ; Huisman et al.
2006 ). High concentrations of nutrients due to global warming could thus severely
deteriorate the quality of DOM-rich waters.
, NO 3
, and NO 2
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