Main Pattern of the Caspian Sea Surface Oil Pollution Revealed by Satellite Data

Abstract

Over the years, oil pollution has been the primary environmental problem of the Caspian Sea. In this paper, we present the results of our satellite survey in 2019 of the whole aquatic area of the Caspian Sea. These results reveal the spatial and temporal distribution of hydrocarbon films of various origins on the sea surface. Our primary attention was focused on the main types of petroleum hydrocarbon films polluting the sea surface. They get into the aquatic area via several different ways: (i) from natural marine hydrocarbon emissions from the seabed; (ii) from the mouths of numerous mud volcanoes; (iii) from offshore oil production and transportation; (iv) from oily wastewaters discharged by ships. We mapped the petroleum hydrocarbon pollution of the Caspian Sea surface on the base of satellite data. For each type of pollution, specific manifestation features were revealed, regions of regular pollution occurrence were outlined, and polluted areas were estimated. The relative contribution of every kind of pollution to the total oil pollution of the Caspian Sea is assessed on the base of satellite data. Comparison with the previous results of our long-term survey of the Caspian Sea is made. The problem of reliability of quantitative estimates of surfaced oil volumes on the base of slick areas seen in the satellite images is discussed.