445
Fluorescent Dissolved Organic Matter in Natural Waters
Coble (1996) firstly designated the fluorescence Ex/Em wavelength peaks of
humic-like substances (peak C, peak M, and peak A) as well as of protein-like,
tryptophan-like and tyrosine-like ones (peak T and peak B). Parlanti et al. (2000)
slightly modified the wavelength ranges and designated them with new letters (α,
β and ά, and γ and δ, respectively). Chen et al. (2003) selected the wavelength
boundaries at various regions (Region I, Region II, Region III, Region IV, and
Region V) to define DOM in natural waters. To account for all the FDOM components of allochthonous, autochthonous and anthropogenic sources, it is desirable
to generalize the peak positions by combining the peak regions (Chen et al. 2003)
and specifying the letters as made by Coble (Coble 1996). All aquatic scientists
have accepted Coble`s specification, and further speciation makes it more complicated. Overviewing and justifying the wavelength ranges of the fluorescence
Ex/Em peaks of Coble (1996) and Parlanti et al. (2000) with those of the field
observations, Mostofa et al. (2009a) summarize and then specify the fluorescence peaks of various FDOM components at four regions: peak C-region
(280–400/380–550 nm), peak A-region (215–280/380–550 nm), peak T-region
(260–285/290–380 nm), and peak T UV -region (215–260/280–380 nm) (Table 1)
(Mostofa et al. 2009a).
Peak C-region accounts for the broader excitation–emission wavelength ranges
at Ex/Em = 280–400/380–550 nm, which include the humic substances (fulvic acid and humic acid) of terrestrial vascular plant origin (C-like and M-like),
autochthonous fulvic acids (C-like and M-like) of algal or phytoplankton origin,
photo-bleached allochthonous fulvic acid, fluorescent whitening agents (FWAs)
such as DAS1 and DSBP as well as few standard organic substances (Tables 1,
2) (Coble et al. 1990, 1998; Coble 1996, 2007; Mopper and Schultz 1993;
Parlanti et al. 2000; Yamashita and Tanoue 2003a; Mostofa et al. 2005a; Stedmon
et al. 2003, 2007a, 2007b; Fulton et al. 2004; Mostofa et al. 2010, 2007a; 2005b;
Mostofa KMG et al., unpublished data; Moran et al. 2000; Komaki and Yabe
1982; Schwede-Thomas et al. 2005; Baker 2005; Sugiyama et al. 2005; Moberg
et al. 2001; Chen et al. 2003; Klapper et al. 2002; Komada et al. 2002; Nagao
et al. 2003; Boyd and Osburn 2004; Burdige et al. 2004; Conmy et al. 2004;
Fu et al. 2006, 2010; Mostofa et al. 2007b; Gao et al. 2010).
Peak A-region accounts for the shorter wavelength region at Ex/Em = 215–
280/380–550 nm, and all FDOM components showing fluorescence at the peak
C-region can display their secondary fluorescence peaks at the A-region
(Tables 1, 2) (Mostofa et al. 2009a, 2005a, 2010, 2007b; Coble et al. 1990; Coble
1996; Mopper and Schultz 1993; Parlanti et al. 2000; Fulton et al. 2004; Komaki
and Yabe 1982; Schwede-Thomas et al. 2005; Baker and Curry 2004; Chen et al.
2003; Klapper et al. 2002; Boyd and Osburn 2004; Burdige et al. 2004; Fu et al.
2006, 2010; Suzuki et al. 1997; Zhang et al. 2009a). Peak T-region accounts for
the fluorescence peaks at Ex/Em = 260–285/290–380 nm, which includes the
primary and secondary fluorescence peaks of various organic substances such as
protein-like, aromatic amino acids (tryptophan-like, tyrosine-like and phenylalanine-like), phenol-like compounds, algae, corals, benzoic acid, p-hydroxy benzoic acid, perylene, phenanthrene, o-cresol and p-cresol (Table 1) (Mostofa et al.
Fluorescent Dissolved Organic Matter in Natural Waters
Coble (1996) firstly designated the fluorescence Ex/Em wavelength peaks of
humic-like substances (peak C, peak M, and peak A) as well as of protein-like,
tryptophan-like and tyrosine-like ones (peak T and peak B). Parlanti et al. (2000)
slightly modified the wavelength ranges and designated them with new letters (α,
β and ά, and γ and δ, respectively). Chen et al. (2003) selected the wavelength
boundaries at various regions (Region I, Region II, Region III, Region IV, and
Region V) to define DOM in natural waters. To account for all the FDOM components of allochthonous, autochthonous and anthropogenic sources, it is desirable
to generalize the peak positions by combining the peak regions (Chen et al. 2003)
and specifying the letters as made by Coble (Coble 1996). All aquatic scientists
have accepted Coble`s specification, and further speciation makes it more complicated. Overviewing and justifying the wavelength ranges of the fluorescence
Ex/Em peaks of Coble (1996) and Parlanti et al. (2000) with those of the field
observations, Mostofa et al. (2009a) summarize and then specify the fluorescence peaks of various FDOM components at four regions: peak C-region
(280–400/380–550 nm), peak A-region (215–280/380–550 nm), peak T-region
(260–285/290–380 nm), and peak T UV -region (215–260/280–380 nm) (Table 1)
(Mostofa et al. 2009a).
Peak C-region accounts for the broader excitation–emission wavelength ranges
at Ex/Em = 280–400/380–550 nm, which include the humic substances (fulvic acid and humic acid) of terrestrial vascular plant origin (C-like and M-like),
autochthonous fulvic acids (C-like and M-like) of algal or phytoplankton origin,
photo-bleached allochthonous fulvic acid, fluorescent whitening agents (FWAs)
such as DAS1 and DSBP as well as few standard organic substances (Tables 1,
2) (Coble et al. 1990, 1998; Coble 1996, 2007; Mopper and Schultz 1993;
Parlanti et al. 2000; Yamashita and Tanoue 2003a; Mostofa et al. 2005a; Stedmon
et al. 2003, 2007a, 2007b; Fulton et al. 2004; Mostofa et al. 2010, 2007a; 2005b;
Mostofa KMG et al., unpublished data; Moran et al. 2000; Komaki and Yabe
1982; Schwede-Thomas et al. 2005; Baker 2005; Sugiyama et al. 2005; Moberg
et al. 2001; Chen et al. 2003; Klapper et al. 2002; Komada et al. 2002; Nagao
et al. 2003; Boyd and Osburn 2004; Burdige et al. 2004; Conmy et al. 2004;
Fu et al. 2006, 2010; Mostofa et al. 2007b; Gao et al. 2010).
Peak A-region accounts for the shorter wavelength region at Ex/Em = 215–
280/380–550 nm, and all FDOM components showing fluorescence at the peak
C-region can display their secondary fluorescence peaks at the A-region
(Tables 1, 2) (Mostofa et al. 2009a, 2005a, 2010, 2007b; Coble et al. 1990; Coble
1996; Mopper and Schultz 1993; Parlanti et al. 2000; Fulton et al. 2004; Komaki
and Yabe 1982; Schwede-Thomas et al. 2005; Baker and Curry 2004; Chen et al.
2003; Klapper et al. 2002; Boyd and Osburn 2004; Burdige et al. 2004; Fu et al.
2006, 2010; Suzuki et al. 1997; Zhang et al. 2009a). Peak T-region accounts for
the fluorescence peaks at Ex/Em = 260–285/290–380 nm, which includes the
primary and secondary fluorescence peaks of various organic substances such as
protein-like, aromatic amino acids (tryptophan-like, tyrosine-like and phenylalanine-like), phenol-like compounds, algae, corals, benzoic acid, p-hydroxy benzoic acid, perylene, phenanthrene, o-cresol and p-cresol (Table 1) (Mostofa et al.