Environmental Engineering Reference
In-Depth Information
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 solu-
tions (Fig.
3
k, 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PARAFAC modeling, unpublished data; Yamashita and Jaffé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.
3
k, l). In contrast, allochtho-
nous fulvic acid (M-like) shows more intense fluorescence (often twofold) at peak
A-region than at peak C-region (Fig.
3
c). 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 instrumen-
tation (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 originat-
ing 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unpublished data).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 chal-
lenges. 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 sub-
strate 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.
3
m, n; Tables
1
,
2
). The
EEM images of the protein-like component show that the fluorescence intensity at
