Environmental Engineering Reference
In-Depth Information
a lot of organic substances including most notably low molecular weight (LMW)
CDOM that are not colored, not being able to absorb radiation in the visible range.
For example, acetaldehyde absorbs light at 208-224 nm (Strome and Miller
1978
;
Kieber et al.
1990
; Mopper et al.
1991
), acetate at 204-270 nm (Wetzel et al.
1995
; Dahlén et al.
1996
), formaldehyde at 207-250 nm (Mopper and Stahovec
1986
; Kieber et al.
1990
; Mopper et al.
1991
), glyoxal at <240 nm (Mopper and
Stahovec
1986
; Mopper et al.
1991
, malonate at 225-240 nm (Dahlén et al.
1996
),
pyruvate at 200-227 nm (Kieber et al.
1990
; Mopper et al.
1991
; Wetzel et al.
1995
) and propanal at ~230 nm (Mopper and Stahovec
1986
). These organic com-
pounds are definitely not colored, but they contribute to the absorption of radiation
by water in the relevant wavelength ranges. It is thus shown that, while all colored
DOM is also chromophoric DOM, not all the chromophoric DOM is also colored.
6 Importance of CDOM Studies in Natural Waters
CDOM is a major bio-optical parameter because of its strong light-absorbing
properties. These properties are involved in some very important biogeochemical
processes and are very useful for detection techniques. Implications are: (i) remote
sensing of CDOM in natural waters; (ii) DOM dynamics in natural waters; (iii)
Photoinduced degradation of CDOM and its impact in natural waters; and (iv)
Protection of microorganisms from UV radiation by CDOM.
6.1 Remote Sensing of CDOM in Natural Waters
Remote sensing is widely used to estimate the ocean color constituents such as chlo-
rophyll
a
and algae, and also to assess primary productivity, occurrence of toxic
dinoflagellate, total suspended solids (TSS), tripton (inorganic suspended particu-
late matter), inherent optical properties, CDOM contents, diffuse attenuation coef-
ficients (
K
d
), DOC concentration and transport from rivers to lakes and oceans
(Coble
2007
; Del Castillo and Miller
2008
; Carder et al.
1991
; Carder et al.
1999
;
McClain et al.
2004
; O'Reilly et al.
1998
; Ferreira et al.
2009
; Tzortziou et al.
2007
;
Son et al.
2011
; Sathyendranath et al.
1989
; Woodruff et al.
1999
; Stramski et al.
2001
; Volpe et al.
2011
; van der Woerd et al.
2011
; Le et al.
2011
; Carvalho et al.
2011
; Santini et al.
2010
; Matthews et al.
2010
; Doxaran et al.
2002
; Cui et al.
2010
;
Zibordi et al.
2009
; Werdell et al.
2009
; Tomlinson et al.
2009
; Friedrichs et al.
2009
; Van Der Woerd and Pasterkamp
2008
; Hunter et al.
2008
; Brown et al.
2008
;
Zawada et al.
2007
; Mélin et al.
2007
; Tzortziou et al.
2006
; Koponen et al.
2007
;
Kishino et al.
2005
; Phinn et al.
2005
; Vahtmäe et al.
2006
; Zimba and Gitelson
2006
). Satellite remote sensing is also used to monitor cyanobacterial blooms in
natural waters, which can be detected from a small peak in reflectance spectra near
650 nm that is specific of cyanobacteria (Matthews et al.
2010
; Kutser et al.
2006
;
