Atmospheric Environment 39 (2005) 7620–7632 Study of the origin of atmospheric mercury depletion events recorded in Ny-A ˚ lesund, Svalbard, spring 2003 Pierre-Alexis Gauchard a,Ã , Katrine Aspmo b,c , Christian Temme d , Alexandra Steffen e , Christophe Ferrari a,f , Torunn Berg b , Johan Stro¨m g , Lars Kaleschke h , Aure´lien Dommergue a,d , Enno Bahlmann d , Olivier Magand a , Fre´ de´ ric Planchon a,i , Ralf Ebinghaus d , Cathy Banic e , Sonia Nagorski a , Patrick Baussand j , Claude Boutron a,k a Laboratoire de Glaciologie et Ge´ophysique de l’ Environnement du C.N.R.S., 54 rue Molie`re, BP 96, 38402 Saint Martin d’He`res, France b Norwegian Institute for Air Research (NILU), Instituttveien 18, P.O. Box 100, N-2027, Kjeller, Norway c Department of Chemistry, University of Oslo, P.O. Box 1033, Oslo, Norway d Institute for Coastal Research, GKSS Research Centre Geesthacht, D-21502 Geesthacht, Germany e Air Quality Research Branch, Meteorological Service of Canada, Environment Canada, 4905 Dufferin St., Toronto, Canada M3H 5T4 f Polytech’ Grenoble, Universite´Joseph Fourier (Institut Universitaire de France), 28 Avenue Beno^ {t Frachon, BP 53, 38041 Grenoble, France g Institute of Applied Environmental Research (ITM), Frescativa ¨ gen 54, S-106 91 Stockholm, Sweden h Institute of Environmental Physics, University of Bremen, Germany i Environmental Sciences Department, University of Venice, Calle Larga S. Marta, 2137, I-30123 Venice, Italy j Groupe de Recherche sur l’Environnement et la Chimie Atmosphe´rique, 39-41 Boulevard Gambetta, 38000 Grenoble, France k Unite´s de Formation et de Recherche de Me´canique et de Physique, Universite´Joseph Fourier (Institut Universitaire de France), BP 68, 38041 Grenoble, France Received 30 October 2004; received in revised form 16 May 2005; accepted 3 August 2005 Abstract An international campaign involving six teams was organized in Ny-A ˚ lesund, Svalbard, in order to understand better the origin of atmospheric mercury depletion events (AMDEs). Special emphasis was given to determining the source region of the observed events and the physical and chemical processes leading to AMDEs. Five AMDEs were recorded during a one-month field experiment (10 April–10 May, 2003). The different events presented various characteristics, especially in terms of mercury species formation, atmospheric particle variations and meteorological conditions. After careful examination of each event, we postulate that two were probably due to advection of already depleted air masses and three were a product of local or regional chemistry. The roles of different surfaces (frost flowers, snow, ice aerosol in clouds) involved in heterogeneous reactions leading to AMDEs are also discussed. We speculate that ice clouds may explain the particle variations observed during the three more local events. r 2005 Elsevier Ltd. All rights reserved. Keywords: Atmospheric mercury depletion events; Mercury; Ozone; Particles; Transport ARTICLE IN PRESS www.elsevier.com/locate/atmosenv 1352-2310/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2005.08.010 Ã Corresponding author. Tel.:+33 476 82 42 39; fax:+33 476 82 4201 E-mail address: ferrari@lgge.obs.ujf-grenoble.fr (C. Ferrari).