PARENT SESSION
PS20 - Passive Samplers for POPs
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P195) Investigations into the kinetic uptake and depuration behaviour of passive air samplers.
Sweetman, Andy*,1, Durham, Louise1, Larre, Marie1, Harner, Tom2, Corrigan, Brian1, Farrar, Nick1, Jones, Kevin1, 1 Environmental Science Department, Lancaster University, Lancaster, UK2 Meteorological Service of Canada, Air Quality Research Branch, Toronto, Ontario, Canada
ABSTRACT- Passive air samplers have enormous potential as they are cheap to deploy and can be used simultaneously at numerous sites to obtain data on local or regional scale air-concentrations. However, it is important that sampling characteristics are fully investigated so that POP concentrations measured in the passive sampler can be either directly related to air concentrations derived by conventional techniques such Hi-Volume air samplers, or to allow comparison between sites. A range of laboratory chamber and wind tunnel experiments have therefore been carried out, to investigate the uptake and depuration kinetics of a range of passive samplers under differing environmental conditions including; temperature, air-flow and humidity. The studies have consisted of controlled chamber experiments with SPMDs and wind tunnel experiments with SPMDs, POGs and PUF discs. The SPMD chambers were constructed of box-section glass and which were designed to allow a short section of SPMD to be suspended in the over which air is passed at a pre-determined rate. The chamber is placed in a water bath to allow ambient temperature conditions to be controlled. The first chamber studies have involved investigation of the factors that control the depuration of 14C labelled phenanthrene. Depuration of chemical added to the triolein is the most direct technique for studying the air-membrane-triolein transfer kinetics as this does not require a constant atmospheric concentration of chemical which would be required for studying uptake. Results show that both wind speed and temperature affect depuration with an apparent threshold wind velocity below which depurations rates reduce considerably. This suggests that depuration can be limited by diffusion through a stagnant boundary layer at the surface of the SPMD. Results from the wind tunnel experiments, which have investigated uptake from laboratory air, have shown a similar dependence on temperature and wind speed.
Key words: passive, sampling, air, POPs