EXPERIMENTAL STUDY ON FLUORIMETRY FOR MEASURING OIL IN SEAWATER

The portable oil measuring instrument using modem fluorimetry, double channel andsingle-chip micro computer control technique, is a new marine optical electronical instrument usedfor measuring trace-oil in seawater. The instrument can detect fluorescence signals produced by oilin seawater, adopting xanon lamp with low consurnption, low repeat frequence and pulse detectingtecboques. It works well from sea surface to 25m depth under any light condition.In September, 1997, experimental measurement of the mixture consisting of filtered Qngdaoseawater and oi1 was performed in a laboratory tank, using the oil insitu fluorometer (OISD.Various oil concentrations were made by addition of known amounts of oil insolution to a knownvolume of water, the fluorescence was measured for each concentration and the calibration curveswere acquired. The experimental results show that under the same experimenta condition, correlationbetween the OISF data and Iaboratory fluorometer Rf54O data is very wel1 with rO.995. Assumingno fluorescence contaminants (e.g. yellow, inorganic and planktonic substances) its measdring rangefor oil in the water is from 1×10-9g/ml-1 ×10-5g/ml。In practical marine measurements, the influence of natural fluorescence substance onmeasuremental results cannot be eliminated fully, due to the limit of excitation and emission filtersof the oil in-situ fluorometer. Therefore, the effect of fluorescence condriinants must be taken intoaccount when in water oil is measured by the fluorometer. While insitu measurement is performed,surface water samples should be collected and analyzed by the fluorometer and GC/MC instruments.finally, the acquired sample concentration and analytic results of the yellow substance, p1ankton et al.should be used for correcting and validating calibration curves of the fluoremeter in laboratory.