164
absorbed before leaving the filter.
In the analysis for absorption
we have determined the optical density of the sample for collimated
light, and with appTopriate scaling to account for the higher absorption
for diffuse light relative to·collimated light we use the ODS (683,1) to
estimate Q:
Q = lO-[OD S (683,1) • C]
Eq. 10
where C is the scaling factor which we have found to be approximately 2.
One can now define a corrected fluorescence spectrum Flc(Ai in terms of
the above algorithm:
Fl u (A)
FlC (A)
E (A) • Q
Eg. 11
so that:
~fl (A)
FlC (A)
X> ODS (A)
Eq. 12
Figure 6 illustrates, in the top panel, the overall consequences
one can expect if correction for only the system excitation is considered.
For increasing densities of Dunaliella on the filter, an initially linear
region is followed by a region where quenching becomes dominant. When
the algorithm described above is applied, the data become linerarized,
as seen in the lower panel of figure 6. The range within which we routinely work corresponds to the region above 20 mI., where ODS(A,l) is
greater than about 0.15 in the maximally absorbing regions of the Soret
bands. Clearly, if one , .. ants to compare spectra in more than a quali tative way, these corrections should be applied.
C. Applications in field studies
Figures 7, 8 and 9 show the results of application of the foregoing
algorithms to a vertical profile taken at a station approximately 200 krn.
west of the southern Baja California peninsula. This station can be
considered typical of stations in the transition zone between the California current and the oligotrophic central Pacific gyre. The mixed
layer extended to a depth of 30 m., contained little chlorophyll, and a
subsurface chlorophyll maximum was found at 70 m.
Figure 7 contains chlorophyll specific volume absorption coefficients
which have units of m 2 /(mg.Chl ~). Two features of spectral absorption
are apparent. First, the magnitude for absorption in the blue region
of the spectra is high in surface and deep water. The increase in the
magnitude of the deep sample can be attributed to photoadaptation since
there is an associated dramatic increase in the absorption in the
absorbed before leaving the filter.
In the analysis for absorption
we have determined the optical density of the sample for collimated
light, and with appTopriate scaling to account for the higher absorption
for diffuse light relative to·collimated light we use the ODS (683,1) to
estimate Q:
Q = lO-[OD S (683,1) • C]
Eq. 10
where C is the scaling factor which we have found to be approximately 2.
One can now define a corrected fluorescence spectrum Flc(Ai in terms of
the above algorithm:
Fl u (A)
FlC (A)
E (A) • Q
Eg. 11
so that:
~fl (A)
FlC (A)
X> ODS (A)
Eq. 12
Figure 6 illustrates, in the top panel, the overall consequences
one can expect if correction for only the system excitation is considered.
For increasing densities of Dunaliella on the filter, an initially linear
region is followed by a region where quenching becomes dominant. When
the algorithm described above is applied, the data become linerarized,
as seen in the lower panel of figure 6. The range within which we routinely work corresponds to the region above 20 mI., where ODS(A,l) is
greater than about 0.15 in the maximally absorbing regions of the Soret
bands. Clearly, if one , .. ants to compare spectra in more than a quali tative way, these corrections should be applied.
C. Applications in field studies
Figures 7, 8 and 9 show the results of application of the foregoing
algorithms to a vertical profile taken at a station approximately 200 krn.
west of the southern Baja California peninsula. This station can be
considered typical of stations in the transition zone between the California current and the oligotrophic central Pacific gyre. The mixed
layer extended to a depth of 30 m., contained little chlorophyll, and a
subsurface chlorophyll maximum was found at 70 m.
Figure 7 contains chlorophyll specific volume absorption coefficients
which have units of m 2 /(mg.Chl ~). Two features of spectral absorption
are apparent. First, the magnitude for absorption in the blue region
of the spectra is high in surface and deep water. The increase in the
magnitude of the deep sample can be attributed to photoadaptation since
there is an associated dramatic increase in the absorption in the