Optical methods in oceanography with special reference to oil fluorometry

Abstract

A single channel profiling oil in-situ fluorometer has been constructed and tested in the marine environment as well as during controlled conditions in the laboratory. Its performance range for oil was shown to lie between 5 ppb up to 100 ppm (5 × 10 −9 and 100 × 10 −6, respectively) assuming no so-named fluorescent contaminants such as dissolved organic, inorganic and planktonic material. The fluorescent contaminants are generally of importance in coastal waters like the Baltic, the North Sea and the Norwegian Coastal Current. Steps taken to correct the total fluorescent signal for these contaminants in order to obtain thefluorescent signal due to oil are described and discussed. It is suggested that single channel oil fluorometry in the sea preferably should be combined with auxilliary optical measurements in order to arrive at reliable quantifications of spatial distribution of oil spills in the sea especially in the vicinity of land, oceanic fronts and pycnoclines, respectively.