Development of a new passive sampler for NO2 and field evaluation in the urban area of Eskisehir, Turkey

Abstract

In this study, a new glass passive sampler for the determination of nitrogen dioxide (NO2) was developed and the performance of this sampler was evaluated in the urban area of Eskisehir in Turkey. One of the two main purposes of this study was field evaluation of this new tailor-made passive sampler for the determination of NO2 for the region. The second purpose was to provide spatial and temporal NO2 distribution in the city through the application of the sampler. The sampler data showed a good agreement with that of Saltzman active monitoring method with an overall accuracy of 8.48%. Method precision in terms of the coefficient of variance (CV) for the applied samplers in triplicates in each sampling site was lower than 9%. A difference of only 4.5% was found between experimental (2.54 mL/min) and theoretical uptake rates (2.43 mL/min). A statistical comparison was carried out between two different colours of glass passive samplers (transparent and brown). There was a significant difference between the results and the results from the brown coloured sampler were higher than that from transparent sampler because of possible photodegradation of NO2-TEA complex during a period from spring to mid-summer. Due to the fragile structure of glass sampler and the desire for clarifying the effect of sunlight on sampler performance, plastic passive samplers were also used. In one sampling site, transparent and brown glass and plastic passive samplers were used in parallel during the same exposure period. A self-consistency study was carried out using glass passive samplers to investigate whether samplers exposed during extended periods give the same response with a series of short-term samplers. The ratio of 4-week average concentration obtained from 4 subsequent 1-week samples to the monthly sample was found 1.19 +/- 0.18 and the ratio of 4-week average concentration obtained from 2 subsequent 2-week samples to the monthly sample was found 1.04 +/- 0.16. By using glass passive samplers, weekly NO2 concentration levels were determined at 6 sampling points during January-August 2004 and weekly average NO2 concentrations were found to vary between 4 and 100 mu g/m(3). Seasonal average concentration value was 34.29 +/- 2.93 mu g/m(3) for winter (January-April) and 26.94 +/- 2.17 mu g/m(3) for summer (April-September). Since NO2 is mostly traffic originated, concentration levels at sites with high traffic density were higher than those at other sites.