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COMPARING FIELD PERFORMANCES OF DENUDER TECHNIQUES IN THE HIGH ARCTIC
Citation:
IANNIELLO, A., H. J. BEINE, M. S. LANDIS, R. K. STEVENS, G. ESPOSITO, A. AMOROSO, AND I. ALLEGRINI. COMPARING FIELD PERFORMANCES OF DENUDER TECHNIQUES IN THE HIGH ARCTIC. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 41(8):1604-2625, (2007).
Impact/Purpose:
The overall research objective of this task is to improve our understanding of the emission, transport, transformation, and deposition of atmospheric mercury. Information garnered from this research is used to improve and evaluate EPA deterministic models that are used to investigate the (i) relative impact to local, regional, and global sources to atmospheric mercury deposition, and (ii) benefits of various emission reduction scenarios.
Description:
A field evaluation between two annular denuder system configurations was conducted during the spring of 2003 in the marine Arctic (Ny-Ålesund, Svalbard). The IIA annular denuder system (ADS) employs a series of five single channel annular denuders, a cyclone and a filter pack to discriminate between gas and aerosol species, while the deployed EPA-Versatile Air Pollution Sampler (VAPS) configuration employs a single multichannel annular denuder to protect the integrity of PM2.5 sample filters by collecting acidic gases. The concentrations of gaseous nitric acid (HNO3), nitrous acid (HONO), sulfur dioxide (SO2) and hydrochloric acid (HCl) determined using the IIA-ADS denuder system were compared to those measured with the EPA-VAPS denuder system. Results for HNO3 and SO2 suggested losses of gas phase species within the EPA-VAPS inlet surfaces due to low temperatures, high relative humidities, and coarse particle sea salt deposition to the VAPS inlet during sampling. The difference in HNO3 concentration (55%) between the EPA-VAPS and IIA-ADS data might also be due to the reaction between HNO3 and NaCl on inlet surfaces within the EPA-VAPS system. Furthermore, we detected the release of HCl from marine aerosol particles in the EPA-VAPS inlet during sampling that contributed to higher observed concentration values. Based on this work we present recommendations on the application of denuder sampling techniques for low concentration gaseous species in Arctic and remote marine locations to minimize sampling errors. We suggest an annular denuder technique without a large surface area inlet device in order to minimize adsorption, absorption, and/or production of gaseous atmospheric pollutants during sampling.