DEVELOPMENT OF A SIMPLE PASSIVE TECHNIQUE FOR THE DETERMINATION OF NITROGEN-DIOXIDE IN REMOTE CONTINENTAL LOCATIONS

This paper describes in considerable detail the improvement of a passive sampling technique for the measurement of nitrogen dioxide in the remote continental atmosphere. The use of ion chromatography reduces the detection limit to 0.02 ppbv week NO2 and enables the detection of other anion constituents. Improvements to the technique were also made by the reduction in contamination of unexposed samplers, such that detectable contamination could be reduced below 0.05 NO2 ppbv week. In addition the samplers have been evaluated for the possible interference from peroxyacetyl nitrate. The accuracy of the samplers was evaluated at a remote site, Aspvreten in Sweden, by intercomparison with three other nitrogen dioxide measurement techniques, NO-ozone chemiluminescence, differential optical absorption spectroscopy and a wet chemical technique, TGS-ANSA (the name derives from the chemical constituents used). The agreement between diffusion tube samplers and other methods lay between + 15 and - 11%, with correlation coefficients around 0.80. Finally a detailed comparison between the samplers and a luminol based nitrogen dioxide detector (Scintrex LMA-3), at a remote Arctic site, agreed within 16% for nitrogen dioxide concentrations between 0.2 and 0.7 ppbv.