A review of the status of advanced technologies for the detection of oil in and with ice

Remote sensors for application to oil in ice and oil with ice are assessed. Radio-frequency methods to detect oil in ice depend on the difference in dielectric properties between oil and water. Freshwater ice is relatively transparent to frequencies below about 200 MHz. Despite extensive theoretical studies, there is a lack of experimental evidence to support the notion that radio-frequency methods have potential. Acoustic methods for the detection of oil in ice show promise. Regular metal inspection equipment is capable of detecting oil layers under ice. Oil propagates shear waves and detection methods based on this unique property are capable of identifying oil in ice. One unit has been built and tested in the field based on this principle. Oil with ice detection is a well developed technology. A common sensor is an infrared camera or an IR/UV (infrared/ultraviolet) system. The inherent weaknesses include the inability to discriminate oil on beaches, among weeds or debris. The laser fluorosensor is a most useful instrument because of its unique ability to identify oil on backgrounds that include water, soil, ice and snow. It is the only sensor that can positively discriminate oil on most backgrounds. Radar offers the only potential for large area searches and foul weather remote sensing, however, there is little potential to detect oil in the immediate vicinity of ice. A major weakness of radar is that it is limited to operation over seas with winds of about 2-8 m/s. Equipment operating in the visible region of the spectrum, such as cameras and scanners, is useful for documentation or providing a basis for the overlay of other data. It is not useful beyond this because oil shows no spectral characteristics in the visible region that can be used to discriminate oil. (author)