On-Site Soil Screening for Volatile Pollutants with an Electronic Nose

Initial investigation has shown that an electronic nose can be used for localizing gas sources in a similar way as the biological nose can. The electronic nose, however, can detect a much wider range of gases (especially electronic noses based on the metal oxide principle, like the Karlsruhe micro nose KAMINA). Furthermore, the electronic nose KAMINA is more stable in terms of sensitivity and can also be employed in hazardous environments without running any risks, and its resolution can be adapted for the task. Localizing gas sources the size of a centimeter was easily possible, so that even smaller objects should be able to be located. For rapid determination of a wider spread of concentration, for instance of some 10 cm up to some meters, as e.g. required in soil analysis for residual waste treatment of volatile and slightly volatile organic pollutants, raster scanning is carried out with a insertion probe (measurement time approx. one minute per raster position). At present the IFIA is continuously working on gas or odor mapping techniques and processes that allow investigation of larger areas with LENA. LENA is a radiocontrolled airship designed for identification of gas emitting objects and equipped with a KAMINA, a GPS system and a video camera. Initial tests have shown that soil-near sampling with the shortest possible gas way to the KAMINA sensor chip is essential for preventing chromatography effects in the gas insertion tube. Localization of a passive source with a resolution smaller than one meter was realized in combination with a gas source recognition test performed in a hall, all samples were taken 30 cm above the ground. The active model source with a methane emission of 8 1/min could still be detected at a flight speed of some km/h, so that raster-scanning of larger areas should not be too time intensive. It will be interesting to see how far these promising results can also be applied to outer air conditions.