Environmental Engineering Reference
In-Depth Information
(f
′
)
The molecular structure of chlorophyll
a
(
f
′) (
Data source
Clarke et al.
1976
)
and two peaks at Ex/Em
=
230/340 and 230/305 nm (peak T
UV
-region) (Determann
et al.
1998
). Note that green algae have been collected from surface waters of Lake
Hongfeng (China) during the summer season using GF/F filters, and their EEM
properties have been determined after re-suspension in Milli-Q and river waters.
Chlorophyll a and Chlorophyll b
Chlorophyll
a
(Chl
a
) shows fluorescence at Ex/Em
=
431/670 nm and chloro-
phyll
b
at Ex/Em
=
435/659 nm (Moberg et al.
2001
). The molecular formula of
Chl
a
is C
55
H
72
MgN
4
O
5
and it molecular weight is 893.49; its chemical structure
is depicted in Fig.
3
f′. The molecular formula of chlorophyll
b
is C
55
H
70
MgN
4
O
6
and its molecular weight is 906.51. The chemical structure of chlorophyll
b
is sim-
ilar to that of Chl
a
, just with the replacement of a methyl group [-CH
3
, marked
with an asterisk (*)] with an aldehyde one (-CHO). Photoexperiments conducted
on sedimentary chloropigments using
14
C-labeled algal cells in combination with
field observations, demonstrate that a major fraction of Chl
a
is rapidly degraded
to soluble colorless compounds (Mostofa et al.
2009a
; Klein et al.
1986
; Bianchi
et al.
1988
; Sun et al.
1993
). Only a minor fraction of Chl
a
(~30-40 %) is
degraded to pheophytin
a
(Klein et al.
1986
; Bianchi et al.
1988
; Sun et al.
1993
).
Identification of Allochthonous Fulvic and Humic Acids
from Autochthonous Fulvic Acid (C-like and M-like) Using
Fluorescence Index
The key component of autochthonous DOM is termed as marine humic-like
substances (Coble
1996
), sedimentary fulvic acid (Hayase et al.
1987
,
1988
) or
