The authors propose a methodology of spectrofluorimetric determination of fluorescence excitation spectra of microalgae cultures. Comparison of the results of laboratory measurements of the experimental sample probing fluorometer FR-1 with the data of laboratory meters was carried out.
The light absorption spectra of an algologically pure culture of the diatom Chaetoceros curvisetus Cleve were obtained for various light conditions and cell concentrations, and their description was given from the point of view of their subsequent use for identification of diatoms based on the analysis of satellite information.
The results of hydrological, hydro-optical and biological studies carried out in autumn 2020 near the coast of Crimea during the 114th cruise of the R/V «Professor Vodyanitsky» are presented. Comparison of the vertical profiles of chlorophyll «a» obtained by different methods has been made. A high convergence was revealed between the fluorescent in situ method for determining the concentration of chlorophyll «a» upon excitation in the blue region of the spectrum and the standard biological in vitro method. The necessity of the simultaneous use of both methods for determining the concentration of chlorophyll «a» and its spatial distribution in sea areas is shown.
Based on the results of hydrological and hydrooptical measurements carried out in the winter of 2020 (November 27 – December 16) off the Crimea coast during the 115th cruise of the R/V Professor Vodyanitsky, the vertical structure of the coefficients of linear relationships between the horizontal distributions of temperature, salinity, density and total suspended matter concentration with a discreteness of 1 m in depth was analyzed. It is shown that the closest linear correlation are founded between temperature, salinity and total suspended matter concentration within the upper quasihomogeneous layer. In this layer, the values of the correlation coefficients between these parameters have a negative sign and exceed 0,75 in absolute value. Below the upper quasi-homogeneous layer, in the layer of high vertical gradients of thermohaline parameters, these connections noticeably weaken, while in the temperature and density fields they change sign and become positive. At the depths of the cold intermediate layer, linear connections increase again. The estimates of the relationships between the distribution of the fluorescence intensity of phycocyanin and phycoerythrin with thermohaline parameters revealed in most cases a low correlation level. A high direct correlation with the values of R ~ 0,65 – 0,75 was revealed only between the distributions of the phycocyanin fluorescence intensity and the temperature distribution under the main thermocline in the 65 – 70 m layer.
The results of hydro-hydro-optical measurements performed in the spring of 2019 in the northern part of the Black Sea off the coast of the Crimea and the Caucasus are presented. It is shown that the maximum concentration of total suspended matter was observed off the coast of the Kerch Peninsula and in the Feodosiya Gulf, which was associated with the coastal transport of the Rim Current of freshened and turbid Azov Sea waters from the Kerch Strait. Minimums of the concentration of total suspended matter were observed at the southern boundary of the polygon in the area of the cyclonic gyre identified by the survey data, and in the southwestern part of the polygon, where the cyclonic meander was recorded. In the vertical structure of the concentration of total suspended matter in the upper 200-meter layer, three main maximums were observed, the depth of which is associated with the features of the circulation and thermohaline waters structure. One maximum was observed in the layer of seasonal thermocline and pycnocline in the eastern part of the polygon. The second maximum was traced below the cold intermediate layer core in the layer of the main pycnocline and halocline in the central part of the polygon at stations located on the periphery of the cyclonic gyre. The third maximum was found in the entire area of the polygon under the main pycnocline and halocline in the sub-oxygen zone.
The results of hydrological and hydro-optical researches carried out in the autumn of 2018 in the Black Sea northern part off the coast of the Crimea and the Caucasus are presented. The features of the spatial distribution of the total suspended matter and their relationship with hydrological parameters are revealed. It is shown that the minimum concentration of the total suspended matter was observed in the western part of the study area. An increase in the concentration of total suspended matter was noted off the coast of the Caucasus, which is associated with the alongshore transport of the Rim Current of turbid and freshened waters of numerous rivers (Rioni, Inguri, etc.). The highest concentrations of suspended matter were found in the coastal zone to the south of the Kerch Peninsula due to the agitation of the bottom and coastal suspensions under the influence of storm conditions. The vertical structure of the concentration of total suspended matter was characterized by a well-pronounced maximum, the depth of which was close to the depth of maximum vertical gradients of temperature and density. The greatest depths of maximum concentration of suspended matter and vertical temperature gradients (40–45 m) were observed to the west of the Heraclean Peninsula in the anticyclonic gyre, the minimum (up to 5–10 m) – in the open deep-sea survey part closer to the central parts of the large-scale Eastern cyclical gyre.
The profiles of the light attenuation coefficients, reconstructed using a model based on statistics of bio-argo floats and regional satellite product, as well as measured under natural conditions in the Black Sea, were compared. Additionally, we compared the values of the attenuation coefficient of photosynthetically active radiation – Kd(PAR), obtained on the basis of spectral measurements of horizontal irradiance, with the results of direct measurements of Kd(PAR) on the shelf and the deep-sea parts of the Black Sea. The effects of meteorological conditions, cloudiness on PAR attenuation in the upper and lower the sea layers are demonstrated.
The results of studying the natural fouling of flat quartz glasses, as well as fouling on the beam attenuation coefficient (BAC) meters’ flat surfaces of objective lens and triple-prism are presented, using the method of spectrophotometry under the same conditions during the plant cover formation. The method based of the obtained empirical data is proposed for registration the biofouling contribution.
Based on the analysis of the backward trajectories of two models: BTA (Back Trajectory Analysis) of AERONET (Aerosol Robotic Network) and HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory model), the periods of arid aerosol drift from the Sahara and the Syrian Desert side were determined by the algorithm of spatiotemporal localization of ground based aerosol sources for 2016. Seasonal variability of arid aerosol during the analyzed period was revealed and a comparative analysis of the BTA data of the AERONET network from 2008 to 2015 and data obtained in 2016 are presented.
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