he passive air sampler based on XAD-2 resin (XAD-PAS) has proven useful for collecting atmospheric persistent organic pollutants (POPs) in remote regions. Due to the open bottom of its housing, wind and other processes causing air turbulence can influence the passive sampling rate (PSR) of the XAD-PAS. Field calibrations of the XAD-PAS are still limited, in particular at sites experiencing high winds. In this study, the PSRs of the XAD-PAS were calibrated at three sampling sites on the Tibetan Plateau, covering a wide range in temperature (T), pressure (P) and wind speed (v). At sites with low wind speeds (i.e. in a forest and an urban site), the PSRs are proportional to the ratio T1.75/P; at windy sites with an average wind speed above 3 m/s, the influence of v on PSRs cannot be ignored. Moreover, the open bottom of the XAD-PAS housing causes the PSRs to be influenced by wind angle and air turbulence caused by sloped terrain. Both a field calibration and computational fluid dynamics (CFD) simulations indicate that a modified design incorporating an air spoiler consisting of 4 metal sheets dampens the turbulence caused by wind angle and sloped terrain. While the original XAD-PAS with an open bottom is suitable for deployment in urban areas and other less windy places, the modified design is preferable in mountain regions and other places where air circulation is complicated and strong.

Field calibration of XAD-based passive air sampler on the Tibetan Plateau: Wind influence and configuration improvement

254th National Meeting (2017)

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