Methodological Features in Measuring the True Light Absorption Spectrum of Monocultures

S. A. Sholar1,*, V. V. Suslin1, L. V. Stelmakh2, N. V. Minina2, O. S. Alatartseva2

1 Marine Hydrophysical Institute of RAS, Sevastopol, Russia

2 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, Russia

* e-mail: sa.sholar@mail.ru

Abstract

This study presents a technique for determining the true light absorption spectrum of a dense culture of the marine coccolithophore Chrysotila sp. using a single-beam MS 122A spectrophotometer equipped with an integrating sphere. The main problem with standard measurements is the distortion of the spectrum due to light scattering by cells, which is especially noticeable in the near-infrared region (750–800 nm), where the pigments are not absorbed, but the signal is not zero. To compensate for the scattering effect, the authors used an approach based on recording absorption spectra at two positions from the integrating sphere: standard (close to) and at a distance of 2 mm. The correction factor, independent of wavelength, was calculated from data in the range of 750–800 nm. Its value was 3.77. The true absorption spectrum, stripped of the scattering contribution, was calculated using the proposed formula. The technique has shown its effectiveness for cultures with a high cell density, providing zero absorption values in the near-infrared region. However, with a low cell concentration, the technique is inapplicable due to a significant increase in errors. Thus, the work demonstrates a practical way to correctly determine in vivo absorption spectra using available equipment, which is important for ecological and physiological studies of phytoplankton as well as for development of regional remote sensing algorithms.

Keywords

spectrophotometry, integrating sphere, light absorption, coccolithophorides, Chrysotila sp., true absorption spectrum, correction factor, in vivo, in vitro, acetone extract

Acknowledgments

The work was carried out under state assignment FNNN-2024-0012 “Analysis, diagnosis and real-time forecast of the state of hydrophysical and hydrochemical fields of marine water areas based on mathematical modelling using data from remote and in situ methods of measurements” (code “Operational Oceanology”) and IBSS RAS state assignment no. 124030400057-4 “Transformation of the structure and functions of marine pelagic ecosystems under conditions of anthropogenic impact and climate change”.

About the authors

Stanislav A. Sholar, Researcher, Marine Hydrophysical Institute of the Russian Academy of Sciences (2 Kapitanskaya St., Sevastopol, 299011, Russia), PhD (Tech.), ORCID ID: 0000-0002-7242-3403, Scopus Author ID: 57189886286, ResearcherID: GSD-9744-2022, sa.sholar@mail.ru

Vyacheslav V. Suslin, Head of the Department of Oceanic Process Dynamics, Leading Researcher, Marine Hydrophysical Institute of the Russian Academy of Sciences (2 Kapitanskaya St., Sevastopol, 299011, Russia), PhD (Phys.-Math.), ORCID ID: 0000-0002-8627-7603, Scopus Author ID: 6603566261, ResearcherID: B-4994-2017, slava.suslin@mhi-ras.ru

Lyudmila V. Stelmakh, Head of the Department of Ecological Physiology of Algae, Chief Researcher, A.O. Kovalevsky Institute of Biology of the Southern Seas of the Russian Academy of Sciences (2 Nakhimov Ave., Sevastopol, 299011, Russia), DSc (Biol.), ORCID ID: 0000-0003-2970-0281, Scopus Author ID: 6603262213, ResearcherID: G-9892-2018, lustelm@mail.ru

Natalya V. Minina, Leading Engineer, A.O. Kovalevsky Institute of Biology of the Southern Seas of the Russian Academy of Sciences (2 Nakhimov Ave., Sevastopol, 299011, Russia), Scopus Author ID: 57223993379, mininachatan@mail.ru

Olga S. Alatartseva, Junior Researcher, A.O. Kovalevsky Institute of Biology of the Southern Seas of the Russian Academy of Sciences (2, Nakhimov Ave., Sevastopol, 299011, Russia), ORCID ID: 0000-0002-9671-2285, Scopus Author ID: 57963185300, moon-23@mail.ru

For citation

Sholar, S.A., Suslin, V.V., Stelmakh, L.V., Minina, N.V. and Alatartseva, O.S., 2026. Methodological Features in Measuring the True Light Absorption Spectrum of Monocultures. Ecological Safety of Coastal and Shelf Zones of Sea, (1), pp. 146–155.

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