Measurements of nitrogen dioxide on Funen using diffusion tubes

Monitoring of nitrogen dioxide (NO2) by passive sampling on the Danish island Funen (Fyn) show that the concentration of nitrogen dioxide is low (2-20 ppb). The level of NO2 in rural and suburban areas is governed by imported air pollution, and elevated NO2 concentrations due to local traffic are of limited importance. These results are supported by diffusion denuder measurements of nitric acid (HNO3) and particulate nitrate. Measurements of NO2 with chemiluminescence and diffusive passive sampling showed good agreement between the methods. The special mounting device for the diffusive samplers used in this work seem to have reduced the turbulence at the open end of the tube. The product from the reaction between nitrogen dioxide and triethanolamine was investigated and tentatively identified as triethanolamine N-oxide, which is in accordance with the observed 1 : 1 stoechiometry in the conversion of NO2 to nitrite ions. (C) 1999 Elsevier Science Ltd. All rights reserved.