Despite of numerous actions undertook by the global and local authorities towards protection of marine environment, oil pollution loads into the Baltic Sea still tend to increase and need to be continuously estimated in order to apply the legal regulations. There is a demand for multifarious studies on the environmental effects of oil products. Dispersed oil droplets occur in seawater as the result of contaminated river inflows, bilge water discharges and as the consequence of mechanical and chemical dispersion of oil spills. Their optical properties depend on oil type, concentration and size distribution. Oil content influences many environmental factors, like water quality and bio-optical parameters (e.g. water-leaving radiance, inherent optical properties, seawater fluorescence). We present a unique study of the collected database of crude oil fluorescence spectra for better understanding the correlations between oil optical properties and its concentration, as well as for evaluation of the oil droplets size by the application of vacuum filtering using three filters of different permeability. Fluorescence spectra have been registered for oil-in-water emulsion samples prepared in the laboratory by mechanical dispersion. We discuss the optical properties of crude oil and the relationships between them in the context of potential remote detection of dispersed oil in seawater.
Oils can be optically described by two parameters: light absorption coefficient and light refraction coefficient. Spectrum of absorption coefficient manifests itself in colour of oil, whereas spectrum of refraction coefficient impacts on both refractive and reflective properties of interface between oil and surroundings. Both spectra of absorption coefficient and refraction coefficient have distinctive slopes in ultraviolet edge of spectrum where values of mentioned coefficients decrease from extremely high in ultraviolet to relatively low in visual range. Possibility of perceiving of oil existing in the form of thin film or in the form of an emulsion depends on ambient light conditions and on mentioned optical properties. Additionally perceiving of oil depends on thickness of the oil film and on type of substrate on which oil is spread (water, metal etc.), as well as - if emulsion oil-in-water or water-in-oil is considered - on the droplets size distribution. The present paper begins with a review of optical properties of several oils. Next, an impact of changes of those properties on optical properties of an oil film (spread on water) as well as an impact of those properties on optical properties of oil-in-water emulsion is explained. Finally, exemplary results of numerical simulation of light transfer in marine environment (using above optical properties) - e.g. angular distributions of optical contrast of both sea areas clean and polluted by an oil-film are presented.
The main task for natural marine environment protection is to prevent the inflow of various contaminants including oil substances and the real challenge is the ability to rapidly detect these pollutants. Moreover important is to find the source or the maker of the oil spill. In this paper, we consider fundamental physical aspects in the area of possibility of monitoring the natural marine ecosystem based on fluorescence spectroscopy. We utilize the fluorescence ability of numerous oil components – mainly polycyclic hydrocarbons. The paper concerns the spectrofluorimetric characterization of oils have been in use during exploitation of the marine fleet, i.e. lubricate oil, fuels, transformer and hydraulic oils as well as crude oils or their residues. Every kind of oil has a chance to enter the marine environment, especially in a case of ship emergency or after collision with other vessel ore shoreline structure as well as when ship enters the stranding. After discharge of oil, some of oil components are dissolved in the water, bacteria or photochemical reactions, which results in transformation of composition of oil, degrade some. Fluorescence spectrometer Perkin Elmer LS55 was applied to obtain the fluorescence spectra using different excitation wavelength in the range from 240 nm to 500 nm. We discuss the changes of the shapes of excitationemission spectra (EEMs) of various types of oil and the EEMs spectra after contact of oil with seawater as an oil-inwater emulsion, which is the most frequent form of oil in the water column. Significant changes in the shape of spectra and displacement of the peaks are observed.
The paper discusses the scattering of radiation by a Baltic crude oil –sea water emulsion. The scattering spectrum calculated using the Mie solution in the spectral range from 380 nm to 730 nm is compared with the measured spectrum of light scattered through a right angle. Spectra in the wavelength range from 210 nm to 730 nm were measured using a spectrofluorimeter for fresh and stored samples of the Baltic crude oil emulsion. Scattering increases with wavelength in the UV range and then decreases slightly with the wavelength of visible light. The result of the calculation is similar to the measured spectra. Both the calculated and measured spectra display numerous relative extremes throughout the spectral area. Light scattering in the emulsion decreases during storage as the oil concentration in the medium diminishes. The results also demonstrate that the single scattering model describes the phenomenon correctly.
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Informacje o procesach zachodzących w toni wodnej przenoszone są w promieniowaniu elektromagnetycznym tylko w jego paśmie widzialnym. Wtrącenia substancji obcych w środowisku wodnym zaburzają naturalny transfer energii promienistej. Okrętowe materiały eksploatacyjne – głównie oleje i paliwa – w przypadku przedostania się do środowiska morskiego wpływają na modyfikację rozkładów prawdopodobieństwa oddziaływań fotonów z wodą i jej składnikami. W niniejszym artykule przedstawiono najważniejsze pojęcia, zjawiska oraz procesy optyczne w środowisku morskim o podwyższonej zawartości substancji ropopochodnych.
EN
Information on natural processes in the water column is transmitted by electromagnetic radiation in the visual range only. Various anthropogenic, alien for marine environment, substances disturb natural transport of the radiant energy. Ship consumables as fuels and lubricants (oils) when entering the marine environment – influences probability distributions of interactions between the solar photons and water constituents. In this paper main phenomena and photonic processes in the environment polluted by oil substances are described.
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