Spatial Variability of Seawater Fluorescence Intensity in the Western Black Sea

Spatial distribution of dissolved organic matter and chlorophyll-a fluorescence intensity in the Western Black Sea is studied in the article. The measurements were carried out during a number of international bio-optical cruises. Their routes passed through the open sea and the coastal areas, including areas exposed to the river runoff of the Danube. The measurements of the spatial distribution of fluorescence intensity were carried out with use of a custom developed flow-through fluorometer with super flux LEDs. UV (373 nm) and green (521 nm) light is used to excite fluorescence in the flow-through fluorometer. A two-channel laser spectrometer is utilized for the purpose of calibration of the obtained data. The calibration allows for determining of the chlorophyll-a fluorescence intensity taking into account the contribution of the DOM fluorescence. The spectrometer operates on samples of seawater. High spatial variability was registered in coastal areas, especially close to the Danube estuary. In open-sea areas the distribution of the measured sea water characteristics was quasi-uniform. Vertical profiles of the fluorescence intensity show high variability in the whole surveyed water area. Daily changeability of the fluorescence intensity was registered in the surface layer of seawater.

1. Hoge F. F., Swift R. N. Airborne dual laser excitation and mapping of phytoplankton in a Gulf Stream warm core ring // Appl. Optics. 1983. V. 22, N. 15. P. 2272–2281.

2. Карабашев Г. С. Флуоресценция в океане. Л.: Гидрометеоиздат, 1987. 200 с.

3. Фадеев В. В., Сысоев Н. Н., Фадеева И. В., Доленко С. А., Доленко Т. А. О возможностях использования флуоресценции гуминовых веществ для определения гидрологических структур в прибрежных морских акваториях и внутренних водоемах // Океанология. 2012. Т. 52, № 4. С. 606–615.

4. Гуреев Б. А., Гольдин Ю. А., Венцкут Ю. И. Проточный лазерный флуориметр // Комплексные исследования Мирового океана — проект «Меридиан», Атлантический океан. М.: Наука, 2008. С. 189–195.

5. Буренков В. И., Гладышев С. В., Гольдин Ю. А. Изменчивость оптических характеристик на разрезе SR-2 в Южной Атлантике // Комплексные исследования Мирового океана — проект «Меридиан», Атлантический океан. М.: Наука, 2008. С. 173–178.

6. Goldin Yu. A., Demidov A. B. Spatial variability of fluorescents intensity and chlorophyll-a distributions in the Atlantic in March-April 2005 // Proc. V Int. Conf. «Current Problems in Optics of Natural Waters» (ONW’2009). Nizhny Novgorod, 2009. P. 193–197.

7. Буренков В. И., Гольдин Ю. А., Артемьев В. А., Шеберстов С. В. Оптические характеристики вод Карского моря по судовым и спутниковым наблюдениям // Океанология. 2010, Т. 50, № 5. С. 716–729.

8. Goble P. G., Castillo C. E., Avril B. Distribution and optical properties of CDOM in the Arabian Sea during the 1995 Southwest Monsoon // Deep-Sea Research II. 1998. V. 45. P. 2195–2223.

9. Amornthammarong N., Zhang J. Z. Shipboard fluorometric flow analyzer for high-resolution underway measurement of ammonium in seawater // Analytical Chemistry. 2008. V. 80, N 4. P. 1019–1026.

10. Checalyuk A. M., Landry M. R., Goericke R., Tayior F. G., Hafez M. A. Laser fluorescence analysis of phytoplankton across a frontal zone in California Current ecosystem // Journal of Plankton Research. 2012. V. 34, N 9. P. 761–777.

11. Карабашев Г. С., Ханаев С. А. Лазерный проточный флуориметр // Океанология. 1987. Т. 27, вып. 6. С. 1007–1009.

12. Майор А. Ю., Букин О. А., Павлов А. Н., Киселев В. Д. Судовой лазерный флуориметр для исследования спектров флуоресценции морской воды // Приборы и техника эксперимента. 2001. № 4. С. 151–154.

13. Parsons T., Takahashi M. Biological oceanographic processes. L. Pergamon Press, 1973. 186 p.

14. Kiefer D. A. Chlorophyll a fluorescence marine centric diatoms: response of chloroplasts to light and nutrient stress // Mar. Biol. 1973. V. 23. P. 30–46.