Evaluation of atmospheric gaseous passive samplers through comparison with active in situ measurements

Abstract

In order to assess compositional changes within the atmosphere it is crucial to measure concentrations of atmospheric trace gas species, which include the criteria pollutants sulphur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃). Measurement of these species with passive samplers is a generally acknowledged and frequently utilised method, which offers a cost-efficient sampling method to monitor these atmospheric species, especially, in data-scarce regions with logistical restraints. However, the performance of these passive samplers must be evaluated regularly, which include comparison to measurements conducted with active in situ samplers that are frequently quality checked and calibrated. In this manner, correction- or scaling factors are determined, which improves the accuracy and precision of passive samplers. Therefore, the aim of this study was to reevaluate passive samplers used to measure SO₂, NO₂ and O₃ in relation to active in situ measurements of these species conducted at the Welgegund atmospheric monitoring station for approximately six years. Scaling factors of 0.9, 1.7, and 1.4 were determined for SO2, NO2, and O3, respectively, measured with passive samplers in relation to active measurements. Concentrations of these species determined with the type of passive samplers used in this study should be multiplied by these factors. These newly derived scaling factors were in the same range as previously determined correction factors. However, statistical analysis revealed that these newly determined scaling factors should be used in future studies utilising these passive samplers.