Colored and Chromophoric Dissolved Organic Matter in Natural Waters - Photobiogeochemistry of Organic Matter - page 364

are generally derived from terrestrial plant materials in soil, while autochthonous
organic substances are produced mostly from algae, phytoplankton and bacteria
within the water column. Allochthonous CDOM (mostly fulvic and humic acids)
originating in terrestrial environments flows through rivers and estuaries onto
coastal shelves and then reaches the open ocean. During such transport it expe-
riences large changes in ionic composition and physicochemical environment
(Mostofa et al. 2009 ; Malcolm 1985 ; Malcolm 1990 ; Wetzel 1992 ; Nakane et al.
1997 ; Uchida et al. 2000 ; Vodacek et al. 1997 ; Mitra et al. 2000 ; Fahey et al. 2005 ;
Murphy et al. 2008 ). Autochthonous CDOM of algal, phytoplankton and bacte-
rial origin is generally composed of autochthonous fulvic acids, carbohydrates,
amino acids, proteins, lipids, organic acids and so on (Nelson et al. 2004 ; Coble
2007 ; Zhang et al. 2009 ; Coble 1996 ; Tanoue 2000 ; Jennings and Steinberg 1994 ;
Rochelle-Newall and Fisher 2002 ; Yamashita and Tanoue 2003 ; Yamashita and
Tanoue 2004 ; Yamashita and Tanoue 2008 ; Stedmon and Markager 2005 ; Stedmon
et al. 2007 ; Stedmon et al. 2007 ; Wada et al. 2007 ; Helms et al. 2008 ; Hulatt et al.
2009 ; Ortega-Retuerta et al. 2009 ; Mostofa et al. 2009 ). Phytoplankton is capable
of releasing 10-60 % of the carbon and 15-50 % of the nitrogen assimilated dur-
ing photosynthesis (Sundh 1992 ; Bronk et al. 1994 ; Braven et al. 1995 ; Malinsky-
Rushansky and Legrand 1996 ; Slawyk et al. 1998 ; Slawyk et al. 2000 ). As a
consequence, CDOM levels are significantly increased after phytoplankton blooms
in natural waters (Billen and Fontigny 1987 ; Ittekkot 1982 ). The contributions of
allocthonous fulvic and humic acids, autochthonous fulvic acids, carbohydrates,
amino acids, proteins, lipids and organic acids are significantly different among
rivers, lakes and oceans. Such differences are discussed in detail in the DOM
chapter.
The absorption and scattering coefficients of water were determined firstly
by the aquatic scientist Gamburtsev in 1924 (cited in Kozlyaninov (MV 1972 ))
and then in other studies (Clarke and James 1939 ; Duntley 1942 ; Yentsch 1960 ;
Preisendorfer 1961 ; Latimer 1963 ; Sullivan 1963 ; Kozlyaninov and Pelevin 1966 ;
Jerlov 1968 ). Jerlov ( 1968 ) has been the first to hypothesize that CDOM in natural
waters absorbs maximally in the blue region of the spectrum and that its absorp-
tion decreases exponentially with increasing wavelength, up to the photosyntheti-
cally available radiation (PAR) waveband. Since then a lot of research studies have
been conducted on the absorption and scattering properties of CDOM, chlorophyll
and particulate material in natural waters (Kozlyaninov and Pelevin 1966 ; Clarke
et al. 1970 ; Tyler and Smith 1970 ; Lorenzen 1972 ; Petzold 1972 ; Morel 1973 ;
Arvesen et al. 1973 ; Clarke and Ewing 1974 ; Duntley et al. 1974 ; Gordon et al.
1975 ; Maul and Gordon 1976 ; Prieur 1976 ; Morel and Prieur 1977 ; Bukata et al.
1979 ; Kirk 1981 ; Gordon and Morel 1983 ; Kirk 1988 ).
High molecular weight DOM, and particularly allochthonous fulvic and
humic acids and autochthonous fulvic acids, absorb radiation along a broad spec-
trum from 250 to 800 nm (Warnock et al. 1999 ; Zhang et al. 2009 ; Jennings and
Steinberg 1994 ; Rochelle-Newall and Fisher 2002 ; Wada et al. 2007 ; Helms et al.
2008 ; Hulatt et al. 2009 ; Ishiwatari 1973 ; Lawrence 1980 ; Zepp and Schlotzhauer
1981 ; Hayase and Tsubota 1985 ; Davies-Colley and Vant 1987 ; Zhang et al.