483
Fluorescent Dissolved Organic Matter in Natural Waters
at 305/378 and <260/378 nm in river and coastal waters; at 295–325/358–420
and 260/385 nm in bay waters; at 310/380–420 and 240–250/384–400 nm in
the coastal waters of South Atlantic Bight; at 325/385 and <260/385 nm in
the deep waters of the Okhotsk Sea and North Pacific Ocean; at 310–315/414–
418 and 260/414 nm in the waters of the north Pacific and Atlantic oceans; at
310–320/380–420 nm in marine waters; at 300/406 and <250/410 nm in drinking
water treatment plants; and at 330/410 and 230/410 nm in compost products solutions (Fig. 3k, l; Tables 1, 2) (Mostofa et al. 2009b; Coble 1996, 2007; Parlanti
et al. 2000; Stedmon et al. 2003, 2007a; Stedmon and Markager 2005a, 2005b;
Zhang et al. 2009a; Luciani et al. 2008; Baghoth et al. 2010; Chen et al. 2010;
Fellman et al. 2010; Yu et al. 2010; Yamashita et al. 2010, 2011, 2008; Balcarczyk
et al. 2009; Murphy et al. 2008; Li et al., Characteristics of sediment pore water
dissolved organic matter in four Chinese lakes using EEM spectroscopy and
PARAFAC modeling, unpublished data; Yamashita and Jaffé 2008; Wang et al.
2007). The autochthonous fulvic acid (M-like) shows much higher fluorescence
intensity at peak C-region than at peak A-region (Fig. 3k, l). In contrast, allochthonous fulvic acid (M-like) shows more intense fluorescence (often twofold) at peak
A-region than at peak C-region (Fig. 3c). The variation in the Ex/Em wavelengths
of the peaks for autochthonous fulvic acid (C-like and M-like) can be caused by
pH, ionic strength, the presence of the trace elements that form complexes with
DOM, water origin (Milli-Q, river, lake and seawater) and solvents, content of
DOM as well as presence and nature of its components, and finally instrumentation (Mostofa et al. 2009a; Senesi 1990a; Coble et al. 1990; Wu and Tanoue
2001a; Wu et al. 2005; Lochmuller and Saavedra 1986). The molecular weight
of autochthonous fulvic acids has been determined as ~<1900 for those originating from photoinduced assimilation of algae under natural sunlight, and ~<1700
upon microbial assimilation of algae in Milli-Q water (Mostofa KMG et al.,
unpublished data). The functional groups of autochthonous fulvic acid (C-like and
M-like) are entirely unknown, which could be the focus for future research challenges. Because of higher fluorescence intensity at the peak C-region compared to
allochthonous fulvic and humic acids, autochthonous fulvic acids of algal origin
are expected to be quite rich in fluorophores. Autochthonous fulvic acid (C-like)
of microbial/algal origin is rapidly decomposed by natural sunlight. This might be
an effect of high fluorescence intensity at the peak C-region, which may be linked
to high reactivity in natural waters (Mostofa KMG et al., unpublished data). It has
recently been found that algal-derived DOM is a more efficient photoinduced substrate than allochthonous DOM (Johannessen et al. 2007; Hulatt et al. 2009).
Protein-like Component
The protein-like component shows two fluorescence peaks at Ex/Em =
280–300/328–356 nm (peak T) in the peak T-region and a peak at Ex/Em =
235–250/338–356 nm (peak T UV ) in the T UV -region (Fig. 3m, n; Tables 1, 2). The
EEM images of the protein-like component show that the fluorescence intensity at
Fluorescent Dissolved Organic Matter in Natural Waters
at 305/378 and <260/378 nm in river and coastal waters; at 295–325/358–420
and 260/385 nm in bay waters; at 310/380–420 and 240–250/384–400 nm in
the coastal waters of South Atlantic Bight; at 325/385 and <260/385 nm in
the deep waters of the Okhotsk Sea and North Pacific Ocean; at 310–315/414–
418 and 260/414 nm in the waters of the north Pacific and Atlantic oceans; at
310–320/380–420 nm in marine waters; at 300/406 and <250/410 nm in drinking
water treatment plants; and at 330/410 and 230/410 nm in compost products solutions (Fig. 3k, l; Tables 1, 2) (Mostofa et al. 2009b; Coble 1996, 2007; Parlanti
et al. 2000; Stedmon et al. 2003, 2007a; Stedmon and Markager 2005a, 2005b;
Zhang et al. 2009a; Luciani et al. 2008; Baghoth et al. 2010; Chen et al. 2010;
Fellman et al. 2010; Yu et al. 2010; Yamashita et al. 2010, 2011, 2008; Balcarczyk
et al. 2009; Murphy et al. 2008; Li et al., Characteristics of sediment pore water
dissolved organic matter in four Chinese lakes using EEM spectroscopy and
PARAFAC modeling, unpublished data; Yamashita and Jaffé 2008; Wang et al.
2007). The autochthonous fulvic acid (M-like) shows much higher fluorescence
intensity at peak C-region than at peak A-region (Fig. 3k, l). In contrast, allochthonous fulvic acid (M-like) shows more intense fluorescence (often twofold) at peak
A-region than at peak C-region (Fig. 3c). The variation in the Ex/Em wavelengths
of the peaks for autochthonous fulvic acid (C-like and M-like) can be caused by
pH, ionic strength, the presence of the trace elements that form complexes with
DOM, water origin (Milli-Q, river, lake and seawater) and solvents, content of
DOM as well as presence and nature of its components, and finally instrumentation (Mostofa et al. 2009a; Senesi 1990a; Coble et al. 1990; Wu and Tanoue
2001a; Wu et al. 2005; Lochmuller and Saavedra 1986). The molecular weight
of autochthonous fulvic acids has been determined as ~<1900 for those originating from photoinduced assimilation of algae under natural sunlight, and ~<1700
upon microbial assimilation of algae in Milli-Q water (Mostofa KMG et al.,
unpublished data). The functional groups of autochthonous fulvic acid (C-like and
M-like) are entirely unknown, which could be the focus for future research challenges. Because of higher fluorescence intensity at the peak C-region compared to
allochthonous fulvic and humic acids, autochthonous fulvic acids of algal origin
are expected to be quite rich in fluorophores. Autochthonous fulvic acid (C-like)
of microbial/algal origin is rapidly decomposed by natural sunlight. This might be
an effect of high fluorescence intensity at the peak C-region, which may be linked
to high reactivity in natural waters (Mostofa KMG et al., unpublished data). It has
recently been found that algal-derived DOM is a more efficient photoinduced substrate than allochthonous DOM (Johannessen et al. 2007; Hulatt et al. 2009).
Protein-like Component
The protein-like component shows two fluorescence peaks at Ex/Em =
280–300/328–356 nm (peak T) in the peak T-region and a peak at Ex/Em =
235–250/338–356 nm (peak T UV ) in the T UV -region (Fig. 3m, n; Tables 1, 2). The
EEM images of the protein-like component show that the fluorescence intensity at