Stedmon and Cory
286
(Jørgensen et al., 2011) and to also apply for CDOM absorption (Nelson et al., 2010).
Earlier experimental work also supports these findings. Rochelle-Newall and Fisher (2002)
and Stedmon and Markager (2005b) have shown how humic-like fluorescence is not evidently produced by phytoplankton directly, but by microbial activity on otherwise colorless DOM. In contrast, amino acid-like fluorescence appeared to be produced during the
300
800
600
400
200
300
350
400
Emission Wavelength (nm)
0
(a)
(b)
HO
OH
HYDROXYANTHRANILIC ACID
SKATOLE
INDOLE
TRYPTOPHAN
TYROSINE
NORADRENALINE
ADRENALIN
CATECHOL
DOPAMINE
O
NH 2
CH 3
N
H
200
100
300
N
H
350
400
HN
OH
OH
OH
OH H
N
OH
OH
OH
(R)
(R)
HO
HO
HO
HO
NH 2
NH 2
OH
H 2 N
H
O
OH
O
HN 2
Emission Wavelength (nm)
Fluorescence (10
–3
Raman units/nm)
Fluorescence (10
–3
Raman units/nm)
0
Figure 8.6. Fluorescence properties and structures of (a) tryptophan and (b) tyrosine compared with
their respective degradation products. (Modified from Determann et al., 1998.)