Main Results of the Satellite Survey of the Baltic and Caspian Seas: Surface Oil Pollution
Mityagina, Marina; Lavrova, Olga
Space Research Institute of Russian Academy of Sciences, RUSSIAN FEDERATION
The presentation summarizes the results of many-year satellite monitoring conducted in aquatic areas of the Baltic and Caspian Seas. Starting from 2009 up to 2012 a satellite survey of the central and south-eastern Baltic and the central part of the Caspian Sea was carried out by the Space Radar Laboratory of the Space Research Institute of RAS. The main attention was focused on the detection of oil pollutions as well as biogenic and anthropogenic surfactant films. The monitoring was based on multi-sensor approach to the detection of oil spills and their drift and spread prediction.
The basic data were high resolution radar images obtained by synthetic aperture radars (SAR) on board Envisat and ERS-2 satellites of the European Space Agency. Remotely sensed data in visual and IR bands taken by sensors Envisat MERIS, Terra/Aqua MODIS and NOAA AVHRR nearly simultaneously with the ASAR images, were involved into consideration in order to reveal the information on the sea surface temperature and the meso-scale water dynamics. Data of scanning radiometers ETM+ and TM onboard the Landsat 7 and Landsat 5 satellites were additionally used. The large amount of the data available allowed us to make some generalizations and obtain statistically reliable results concerning a spatial and temporal variability of various films manifestations in SAR images of the sea surface.
The most typical situations of SAR observation of sea surface areas covered by pollution films were analyzed. It was revealed that the majority of Baltic Sea surface pollutions are caused by oil spillages and waste water discharges by ships along main shipping routes. The maximal pollution areas were found along the shipping routes to the south-east of Gotland Island where the ship oil discharges are characterized by considerable lengths and total area.
A specific attention was paid to a comparison of the sea pollution level observed several years ago with the present time situation. It was revealed that in the south-eastern Baltic the total amount of surface pollution has decreased over last years. Nevertheless the main source of the sea surface pollution namely the illegal oil-containing water discharge is remaining the same.
Two areas of the most intensive pollutions of the Caspian Sea surface were outlined. Those are the oil-producing regions near the Apsheron peninsula and the west bank of the South-Caspian depression.
It was confirmed that the exploration and exploitation of the oilfields in the sea as well as natural seepages and mud volcanoes at the sea bottom are the main sources of the Caspian Sea surface pollution. The relation between certain type's manifestations of surface films in radar imagery of the Caspian Sea and natural seepages and mud activity is discussed.
The dependence of the natural seepages and mud volcanoes manifestations in SAR images on the number and magnitude of earthquakes in South Caspian and adjacent areas was studied. A rather high correlation was revealed between the SAR manifestations of the natural seepages and mud volcanoes and the 3-4-magnitude quakes.
It was established that in distinction with the situation in the Baltic Sea the illegal ship discharges are not the main pollution source in Caspian Sea now. Unfortunately the amounts of this kind of pollutions are increased year by year.
The work is partially supported by RFBR grants 11-07-12025-ofi-m-2011 and 11-05-12047-ofi-m-2011 and the Russian Federal Thematic Program "Scientific and scientific-educational professionals of innovative Russia". ERS-2 and Envisat ASAR data were obtained under ESA projects C1P.6342, C1P.5004, AOBE 2775 è C1P.1027.