Coble, Spencer, Baker, and Reynolds
82
Peak M was originally described from bloom conditions in the Gulf of Maine (Coble,
1996) and was subsequently observed in the upwelling zone of the Arabian Sea (Coble
et al., 1998). This humic-like component was considered to represent a pool of humic
material newly formed in the marine environment. It meets the criteria of a peak distinct
from peak C based on two observations. The first was its appearance in some samples as a
nearly pure fluorophore, with round contours in map view, and the second was the appearance of distinct M and C peaks in some samples (Figure 3.3). Although the original reports
of this component did not include data below 260 nm excitation, it is now clear that peak M
Fluorescence (ppb QSE)
300
0
1
2
3
4
400
500
600
700
300
350
400
450
Excitation (nm)
Emission (nm)
Excitation (nm)
300
300
350
400
450
400
500
600
700
Figure 3.3. Fluorescence fingerprint representative of samples collected in the (Arabian Sea)
upwelling. Water Mass Type 4. Although typical of most samples collected in the cool upwelling
waters, not all had the chlorophyll-like peak at ex/em = 400/685. (Reprinted from Coble et al., 1998,
with permission from Elsevier.) Note that the shortest excitation wavelength was 260 nm; therefore
some of the peaks noted in Table 3.1 were not observed. The peak labeled A in the original figure is
equivalent to peak A C according to the revised nomenclature proposed in this work.