The delayed fluorescence (DF) was measured in vivo on board of the ship.
A cylindrical phosphoroscope in a millisecond fluorescence
decay range (time between the end of excitation and beginning of
measurement being equal to ca 1.5 ms) was used. The signal
from a FEU-84 photomultiplier measuring the fluorescence intensity
was amplified by a millivoltameter and recorded by a strip-chart
recorder.
Samples of sea water from each depth were drawn 4 times a
day (at 0.00, 6.00 12.00 and 18.00 LT) and placed in a special 70 ml
perspex vial. Samples were excited with red light (a 100 W lamp
equipped with a KS-15 red light filter, light intensity 20
Wm-2) in order to reduce the fluorescence of the vial and
the impurities contained in sea water. Samples were drawn from 10
depths, viz 0, 1, 2, 3, 5, 7, 10, 15, 20 and 30 m. Determination of
the delayed fluorescence of all samples took 1 hour.
In some cases, the determination of the delayed fluorescence intensity (L) was carried out after adding of diuron - a photosynthesis inhibitor (DCMU) at a concentration of 5*10-8M. The ratio of fluorescence intensity with the inhibitor added to the intensity without the inhibitor (E=LDCMU/L) was used as a measure of the increase of delayed fluorescence intensity (enhancement coefficient). The applied concentration of the inhibitor was experimentally chosen as a concentration at which the DF enhancement was maximum.
The measurements were carried out by Prof. V. I. Zvalinsky from the Pacific Ocean Oceanological Institute of the Far East Scientific Centre, Academy of Sciences of the USSR, Vladivostok