Distribution and fate of polycyclic aromatic hydrocarbons (PAHs) in recent sediments from the Gulf of Gdańsk (SE Baltic)

摘要

The influx of solar radiation to the Baltic Sea and its penetration into its watersis described on the basis of selected results of optical and bio-optical studies in theBaltic published by various authors during the past ca 50 years. The variabilityin the natural irradiance of this sea is illustrated on time scales from short-termfluctuations occurring during a single day to differences in mean monthly valuesover a period of many years. Data on variability of the proportions between UV,VIS and IR energy in the light reaching the sea surface are also discussed. Longterm monthly mean values of the incident solar radiation flux at the surface ofthe Baltic Proper are given; they were obtained from meteorological and solarradiation measurements and model approximations. The transmittances of thesemean monthly radiation fluxes across the surface of the Baltic are given, as arethe typical energy and spectral characteristics of the underwater irradiance, itsattenuation with depth in the sea and the associated euphotic zone depths, as wellas typical ranges of variability of these characteristics in different Baltic basins.Some of these characteristics are illustrated by typical empirical data. These meanvalues are not fully representative, however, because with the sole use of classical insitu measurement methods from on board research vessels in the Baltic, it has notbeen possible to gather a sufficiently representative set of empirical data that wouldadequately reflect the variability of the optical characteristics of all the basins of thissea. The article goes on to introduce the statistical model of vertical distributions ofchlorophyll a concentration in the Baltic and the bio-optical model of Baltic Case 2waters, the use of which contribute very significantly to this description of theoptical characteristics and will enable this data set to be hugely expanded to includeall the Baltic basins. This opportunity is presented by the optical parameterizationof Baltic Case 2 waters, i.e. by the mathematical formulas of the model linking thecoefficient of attenuation of downward irradiance with the surface chlorophyll aconcentration, as well as the method developed for the efficient and systematicsatellite remote sensing of the chlorophyll a concentration over the entire BalticSea area.