Environmental Engineering Reference
In-Depth Information
substrates produced from DOM and OM either photolytically or biologi-
cally can enhance biological productivity in waters (Mostofa et al.
2009a
;
Bertilsson and Tranvik
1998
,
2000
; Vähätalo and Järvinen
2007
; Lovley et
al.
1996
; Komissarov
2003
; Tranvik
1992
; Norrman et al.
1995
; Wetzel et
al.
1995
). Production of nutrients and DIC through photoinduced and micro-
bial degradation of DOM or POM can control the food-chains for micro-
organisms (Mostofa et al.
2009a
; Miller and Zepp
1995
; Ma and Green
2004
; Tranvik
1992
; Salonen et al.
1992
; Kirchman et al.
1995
; Wheeler
et al.
1997
; Guildford and Hecky
2000
; Rosenstock et al.
2005
). The bio-
geochemical functions of microbial processes are discussed in details in
(3) Optical (or physical) functions of DOM: a fraction of DOM is named as
either colored and chromophoric dissolved organic matter (CDOM) based on
the absorption of ultraviolet (UV) and photosynthetically available radiation
(PAR), or fluorescent DOM (FDOM) based on the emission of fluorescence
photons after radiation absorption. DOM generally controls the downward
irradiance flux through the water column of UV-B (280-320 nm), UV-A
(320-400 nm), total UV (280-400 nm) as well as photosynthetically avail-
able radiation (PAR, 400-700 nm) (Kirk
1976
; Morris et al.
1995
; Siegel and
Michaels
1996
; Morris and Hargreaves
1997
; Tranvik
1998
; Bertilsson and
Tranvik
2000
; Laurion et al.
2000
; Markager and Vincent
2000
; Huovinen
et al.
2003
; Sommaruga and Augustin
2006
; Hayakawa and Sugiyama
2008
; Effler et al.
2010
). DOM is responsible for water color, water trans-
parency, occurrence of the euphotic zone and thermal stratification in the
surface waters of lakes and oceans because it affects (decreases) the pen-
etration of solar radiation (Laurion et al.
2000
; Effler et al.
2010
; Hudson et
al.
2003
; Eloranta
1978
; Jones and Arvola
1984
; Howell and Pollock
1986
;
Perez-Fuentetaja et al.
1999
; Snicins and Gunn
2000
; Watts et al.
2001
;
Mostofa et al.
2005a
). Biogeochemical functions of CDOM and FDOM are
discussed in detail in the respective chapters (see chapters
“
Colored and
(4) Cycling of nutrients (NH
4
, and PO
4
3
−
) by DOM and POM.
Nutrients are produced by degradation of DOM and typically derive from
dissolved organic nitrogen (DON) and dissolved organic phosphorus
(DOP) in DOM molecular structure (Bronk
2002
; Zhang et al.
2004
,
2008
;
Kim et al.
2006
; Vähätalo and Järvinen
2007
; Li et al.
2008
). Nutrients are
mostly released during the photoinduced and microbial respiration (or
assimilation) of POM (e.g. algae or phytoplankton biomass), as shown
by in situ experiments conducted under light and dark incubations (Kim et
al.
2006
; Li et al.
2008
; Yamashita and Jaffé
2008
; Carrillo et al.
2002
;
Kopá
+
+
, NO
3
č
ek et al.
2004
; Fu et al.
2005
; Mostofa KMG et al. unpublished data).
−
−
NO
3
and NO
2
can be produced by oxidation of ammonia in nitrification
+
−
+
2H
+
+
H
2
O) and of DON in lake waters (Ma and
(NH
4
+
2O
2
→
NO
3
