Аннотация:A number of samples for analysis of oil pollution have been prepared by extraction of water of Black Sea western aquatorium between state sea frontiers and 32°E in spring of 1981. Capillary gas chromatography (GC Varian 3700, column 25 m, i.d. 0.25 mm, SE-30, column oven temperature programmed from 50 to 320 °C) was used for identification and quantitative analysis of pollutant n-alkanes. Molecular weight distribution curves for n-alkanes (containing from 14 to 44 carbon atoms) have minima for octa- and nonadecanes, and their relative contents in the sea water are rather low. Hydrocarbons, polluting upper layer of the Black Sea, can be devided into two groups, basing on the form of such curves. C14 - C17 n-alkanes represent the first, while C20 - C38 are the main part of the second group. Maxima of the molecular weight distribution curves shift upwards and downwards on the hydrocarbon molecular weight scale, depending on sampling location. The pollution degree decreases with the distance from the shore, but there is a sharp pollution increase in the vicinity of the Bosphorus strait - Danube delta shipway. The obtained data indicate possible sources of hydrocarbon pollution of the Black Sea.