Environmental Engineering Reference
In-Depth Information
2.3.1 Characterization of FDOM Using EEM in Combination
with PARAFAC
PARAFAC modeling, a three-way method with its origin in psychometrics
(Harshman
1970
; Caroll and Chang
1970
), can be effectively applied to isolate
the EEMs of either an aqueous mixture of organic components or of natural DOM
into their individual fluorescence components (Bro
1997
,
1998
,
1999
; Ross et al.
1991
; Jiji et al.
1999
; Baunsgaard et al.
2000
,
2001
; da Silva et al.
2002
; Stedmon
et al.
2003
,
2007a
,
2007b
; Cory and McKnight
2005
; Mostofa et al.
2010
; Wedborg
et al.
2007
; Hiriart-Baer et al.
2008
; Hunt et al.
2008
; Luciani et al.
2008
;
Kowalczuk et al.
2009
; Ohno et al.
2009
; Zhao et al.
2009
; Baghoth et al.
2010
;
Chen et al.
2010
; Dubnick et al.
2010
; Fellman et al.
2008
,
2009
,
2010
; Guo
et al.
2010
; Singh et al.
2010
; Yu et al.
2010
; Wu et al.
2011
; Yamashita et al.
2010
,
2011
). The EEMs often involve various types of overlapping peaks because of the
natural DOM composition, which makes it difficult to identify the fluorescent com-
ponent peaks and their intensities. PARAFAC, a statistical modeling approach, can
isolate the fluorescent components from EEMs and then determine the concentra-
tion of the fluorescing compounds.
The EEM in combination with PARAFAC analysis has been applied to sepa-
rate and identify the various DOM components and their concentrations in riv-
ers and freshwaters (Mostofa et al.
2010
; Chen et al.
2010
; Fellman et al.
2009
,
2010
; Holbrook et al.
2006
; Hua et al.
2007
; Balcarczyk et al.
2009
), lakes (Cory
and McKnight
2005
; Chin et al.
1994
; Gron et al.
1996
), wetlands (Fellman
et al.
2008
; Holbrook et al.
2006
), estuaries (Stedmon et al.
2003
; Hall et al.
2005
; Stedmon and Markager
2005a
,
2005b
; Fellman et al.
2010
; Santín et al.
2009
), bays and marine waters (Luciani et al.
2008
; Fellman et al.
2010
; Singh et
al.
2010
; Yamashita et al.
2010
,
2011
,
2008
; Murphy et al.
2008
), lake sediment
pore waters (Li et al., Characteristics of sediment pore water dissolved organic
matter in four Chinese lakes using EEM spectroscopy and PARAFAC modeling,
unpublished data), wastewaters (Baghoth et al.
2010
; Guo et al.
2010
; Wu et al.
2011
), landfill leachate (Baker and Curry
2004
; Lu et al.
2009
) and soil (Ohno
and Bro
2006
; Fellman et al.
2008
,
2009
). PARAFAC is also adopted in a wide
range of different applications, such as the identification of autochthonous ful-
vic acids of algal origin that can be distinguished from allochthonous fulvic
acid (Mostofa et al.
2009b
; Stedmon et al.
2007b
; Mostofa KMG et al., unpub-
lished data; Zhang et al.
2009a
; Li et al., Characteristics of sediment pore water
dissolved organic matter in four Chinese lakes using EEM spectroscopy and
PARAFAC modeling, unpublished data). PARAFAC can also be used to trace
photoinduced and microbial changes in DOM components and their intensities
(Cory and McKnight
2005
; Stedmon and Markager
2005a
; Stedmon et al.
2007a
;
Mostofa et al.
2010
), in water source categorization (Hua et al.
2007
) and in cor-
relation with water quality parameters (Hayase and Tsubota
1985
), in the iden-
tification of changes in the fulvic acid redox state (Fulton et al.
2004
; Cory and
McKnight
2005
), and finally in studying interactions between trace metals and
DOM (Yamashita and Jaffé
2008
).
