Environmental Engineering Reference
In-Depth Information
degradation in seawater (Mostofa and Sakugawa
2009
; Zhang et al.
2009
;
Stedmon et al.
2007
). The current works do not distinguish between the photoin-
duced, microbial and metal-complexation processing of the autochthonous DOM
and do not differentiate between e.g. autochthonous fulvic acids and terrestrial ful-
vic and humic acids. Such a differentiation and the elucidation of the behavior of
the single components should be a key focus for future research.
An increase in water temperature due to global warming may significantly alter
the biogeochemical functions in natural aquatic ecosystems. However, there is
currently no study that examines the temperature effect on the metal-complexa-
tion features of fluorescent DOM in waters, which might be another key issue for
future study. It may lead to understand the impacts of global warming on M-DOM
complexation in the aquatic environments.
Fluorescent whitening agents (FWAs) and household detergents show fluores-
cence properties and are widely distributed in the waters and sediments of riv-
ers, lakes and oceans (Mostofa and Sakugawa
2009
; Mostofa et al.
2005
,
2010
;
Managaki and Takada
2005
; Stoll and Giger
1998
; Poiger et al.
1999
; Baker
2002
; Yamaji et al.
2010
). The complexation of trace elements with FWAs such as
diaminostilbene-type
(
DAS1) and distyryl biphenyl (DSBP) and household deter-
gents might be an interesting concern for future research.
The stability constants for the formation of ternary complexes are simi-
lar to those of DOM in surface waters (Tables
1
and
2
) (Khalil and Taha
2004
;
Khalil and Fazary
2004
; Radalla
2010
; Rosas et al.
2010
; Shiozawa et al.
2011
).
Considering the similarity of the stability constants, ternary complex formation
should be taken into account in a speciation description of M-DOM complexation.
It could be vital to understand the high variability of stability constants in natural
waters and should be a focus for future research.
9 Nomenclature
CDOM
Chromophoric dissolved organic matter
DOM
Dissolved organic matter
EDTA
Ethylenediaminetetraacetic acid
EHA
Elliot soil humic acid standard
EPS
Extracellular polymeric substances
FA
Fulvic acid
FDOM
Fluorescent dissolved organic matter
HA
Humic acid
I
Ionic strength
Log
10
K
Conditional stability constant (logarithm)
LFSE
Ligand field stabilization energy
LHA
Leonardite coal humic acid standard
SRFA
Suwannee River fulvic acid
SRHA
Suwannee River humic acid
