Satellite data analysis has enabled the detection of tank-flushing ships dumping products into the Black Sea waters. Satellite-based monitoring of the eastern part of the Black Sea during the 2011 summer season has detected many vast slicks released by vessels. One of them is unprecedentedly large, covering over 420 sq km, and was caused by the tanker Yukon Star washing its tanks.
Specialists from ScanEx Research & Development Center together with the experts from the Shirshov Institute of Oceanology conducted a complex analysis of available data that revealed that tank washing can be conducted both legally, in compliance with the MARPOL-73/78 convention, and with violations of accepted standards.
For example, the inspection, carried out in the port of Tuapse, revealed that the Yukon Star tanker conducted tank-washing from palm oil on 23 to 25 June 2011 within the area of detected spill. Palm oil is category-D rated according to MARPOL convention (Supplement I, Attachment II) and in generally poses no threat to the sea environment and to human health.
However, the convention nonetheless prohibits the dumping of substances of the D category into the sea with exception of cases in which all the following requirements are met: first of all, the ship should be in motion, sailing at speeds not less than 7 knots if it is self-propelled or at least 4 knots if it is not self-propelled. Secondly, the concentration of such mixtures should not exceed one part of the substance in ten parts of water. Thirdly, the dump should take place at least 12 nautical miles away from the shore, explains senior researcher of the Institute of Oceanology Andrei Ivanov.
Joint analysis of radar satellite images and of AIS system later on showed that the Yukon Star tanker was outside the 12-mile zone and its average speed was 7-8 knots. The tanker dumped quite a big volume of water mixture with the residuals of the product of unknown concentration. The vessel performed five multi-kilometre traverses within three days to do that. As a result the total acreage of spill constituted 423.5 sq km, which is the record for spills ever registered in the Black Sea. However, the inspection examining foreign ships in the port of Tuapse, perfomed on 30 June 2011, found no violations of the convention requirements - the tank-washing procedure complied with general standards and in particular with recommendations of the Tank Cleaning Guide guidelines.
The situation around the Tarik Emir tanker is somewhat different. It did not drop at the Russian ports, so the inspection was impossible. The spill it made (185 sq km in acreage) probably did not meet the MARPOL requirements, as the concentration was unknown and contained heavy fractions of unknown oily product (judging by the feather-like structure of the slick). The slick trails could be seen on RADARSAT-1 radar images from 8 August 2011 and on ENVISAT-1 images from 9 August 2011, i.e. 3-4 days after the spill was created.
Analysis of the satellite monitoring data revealed that similar slicks of dozens and hundreds of square kilometres within the Russian sector of the Black Sea and near the border with the Turkish sector were detected on several other radar images (from 28.10.2008 and 28.05.2009, 15.05.2011 and 21.06.2011). The probable source of these large-size ship spills is the washing of tanks in the open sea after shipping vegetable oils and other substances and, probably, oil products.
Cases of tanks flushing, detected by satellite images, that are conducted on the borders or directly within Russian sector of the sea and sometimes beyond the reach of the coastal AIS systems require control for abidance by the MARPOL convention agreements. Probably, legal restrictions on tanks flushing, for example, a mandatory delivery of washing wastes to the port services (the way it is done in the Baltic Sea) is required. Satellite-based radar assets proved to be reliable tools of detecting facts of large ship spills. Russian nature protection agencies need to conduct a detailed examination of this newly-arising problem and to use radar imagery data more efficiently as evidence, says Deputy General Director of ScanEx RDC Alexei Kucheiko.
Local technology of complex processing and analysis of radar images of three foreign satellites - RADARSAT-1, RADARSAT-2 and ENVISAT - were used during monitoring. This ensures a steady increase of imaging frequency for monitoring transformations of detected spills. Integration of satellite images and AIS data enables in most cases a quick and highly reliable detection of the offending ships, explains head of the ScanEx's Operational Maritime Monitoring Department Nataly Philimonova.
Issues related to the use of satellite data for monitoring and control of marine environmental and navigation situation will be tackled at the 5th International Conference 'Earth from Space - the Most Effective Solutions'. This event will take place from 29 November to 1 December 2011 at the Moscow Region 'Vatutinki' complex.