Spatial Variability of Seawater Fluorescence Intensity in the Western Black Sea

Goldin Yu. A., Shatravin A. V., Levchenko V. A., Ventscut Yu. I., Gureev B. A., Kopelevich O. V.

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.

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