Spectral phytoplankton pigments absorption coefficient

Determining the spectrum of the coefficient of light absorption by phytoplankton is a complex experimental problem. One of the most reliable methods is the nonextract spectrophotometric method - direct measurements of light absorption spectra in isolated phytoplankton in vivo samples. Such measurements are made on samples of natural phytoplankton (or cultivated cultures) concentrated on filters. In order to eliminate the scattered light, the spectrophotometers are equipped with integrating spheres or diffusers made of milky glass. The measurement consists of following steps:
1. - filtering,
2. - measurement of spectrum,
3. - bleaching (depigmentation),
4. - second measurement of spectrum.

The difference between absorption measured before and after bleaching gives a value of absorption by living phytoplankton pigments. The after-bleaching spectrum gives information about the absorption by remaining particular matter.

Database contains the results of measurements carried out by various specialists from other institutes during joined cruises. So the methodological details vary in each dataset. The differences are briefly described in the table below.

Vessel, expedition,
year
Filters,
pores size [micrometer]
Spectrometer,
Regime of measurements
CorrectionBleaching method
"Vityaz" 64
1978
SYNPOR N4
+ BaCO3 layer
0.85
SF-14
Sample and reference filters in the middle of Ulbricht's sphere
K factor
Konovalov (1985)
UV+H2O2
"Profesor Siedlecki" 14
1980
Nucleopore
1
Specord UV-VIS
Shibata et al. (1954) method
For the number of filter layersFreezing
solvents
alkali
Akademik Kurchatov" 39
1984
SYNPOR N5
+ BaCO3 layer
0.65
SF-18
Sample and reference filters in the middle of Ulbricht's sphere
beta factor
Konovalov (1992) (eq. 1)
UV+H2O2
Experiment SOPOT'87
1987
GF/C
1.2
SF-18
Sample and reference filters in the middle of Ulbricht's sphere
beta factor
Konovalov (1992) (eq. 2)
UV+H2O2
"Professor Shtokman" 25
1990
GF/F
0.6
SF-18
Sample and reference filters in the middle of Ulbricht's sphere
beta factor
Konovalov (1992) (eq. 2)
Ca(OCl)2
2% sol.
Campaign ULISSE
1993-1994
GF/F
0.6
PERKINS-ELMER LAMBDA 19 + integrating sphere
combination of light reflection and light transmission measurements (Tassan and Ferrari 1995)
beta factor
(Tassan and Ferrari 1995) (eq. 3)
Ca(OCl)2

Equations:

1) beta(lambda)=(0.0021 lambda - 6.35) D + 0.00073 lambda + 4.38

2) beta(lambda)=(0.00234 lambda - 4.54) D + 0.00033 lambda + 2.92

3) beta(lambda)=0.49 D2 + 0.417 D

where D is the optical density of the sample on the filter and lambda is expressed in nanometers.

Please contact Slawomir Kaczmarek for more detailed information.

References:

Konovalow B. V., 1985, Light absorption capacity of phytoplankton pigment, In: O.J. Koblentz Mishke, B. Wozniak, I.E. Ochakovskii [Eds.], Utilization of solar energy in the process of photosynthesis by the Black Sea and Baltic phytoplankton, Moskva, 59-71, (in Russian).

Konovalov B. V., 1992, Opredelenie pokazatelia pogloshchniia sveta komponentami sestona po spektru pogloshcheniia ego osadka na membrannom filtre, Okeanologiia, 32(3), 588-593.

Tassan S., Ferrari M. G., An alternative approach to absorption measurements of aquatic particles retained on filters,

Shibata K., Benson A. A., Calvin M., 1954, The absorption spectra of suspension of living micro-organisms, Biochim. Biophys. Acta, 15, 461-471.