* Corresponding author. Tel.: #33-4-76-82-42-00; fax: #33- 4-76-82-42-01. E-mail address: boutron@glaciog.ujf-grenoble.fr (C. Boutron). Atmospheric Environment 35 (2001) 415}425 Heavy metals in fresh snow collected at di!erent altitudes in the Chamonix and Maurienne valleys, French Alps: initial results Audrey Veysseyre, Kerno Moutard, Christophe Ferrari, Katja Van de Velde, Carlo Barbante, Giulio Cozzi, Gabriele Capodaglio, Claude Boutron* Laboratoire de Glaciologie et Ge & ophysique de l'Environnement du CNRS, 54, rue Molie % re, B.P. 96, 38402 Saint Martin d'He % res, France Institut des Sciences et Techniques, Universite & Joseph Fourier de Grenoble, 28 Avenue Benon L t Frachon, B.P. 53, 38041 Grenoble, France Dipartimento di Scienze Ambientali, Universita Ca Foscari di Venezia, Dorsoduoro 2137, 30123 Venezia, Italy Centro di Studio sulla Chemica e le Tecnologie per l'Ambiente, CNR, Dorsoduoro 2137, 30123 Venezia, Italy Unite & s de Formation et de Recherche de Physique et de Me & canique, Universite & Joseph Fourier de Grenoble (Institut Universitaire de France), B.P. 68, 38041 Grenoble, France Received 27 July 1999; accepted 21 January 2000 Abstract The Chamonix and Maurienne valleys, French Alps, are major pathways for international truck and automobile tra$c in Western Europe since they give access to the transalpine Mont Blanc and Frejus road tunnels. Moreover, the seasonal snow pack, which accumulates from autumn to spring in these two valleys, is a major contributor to fresh water resources for a large number of people, especially in large cities such as Geneva, Lyon and Grenoble. During winter 1998, we have collected a series of snow samples from two well-identi"ed snowfall events at various altitudes ranging from 1150 to 3532 m on the sides of these two deep valleys. They were analysed for Li, B, Ti, V, Mn, Fe, Co, Cu, Zn, Mo, Pd, Ag, Cd, Sn, Sb, Ba, Pt, Au, Pb, Bi and U by double focusing inductively coupled plasma mass spectrometry with micro concentric nebulization (DF-ICP-MS-MCN). Ultraclean procedures were used for "eld sampling and laboratory analysis. The results show surprisingly low concentration values. With the exception of Li, B, Pd, Sn, Pt and Au, concentrations are found to decrease with increasing altitude. Crustal enrichment factors larger than $10 times the mean crustal abundance are observed for Cu, Zn, Li, Mo, Pb, Ag, Bi, B, Sb, Sn, Cd, Au, Pt and Pd, strongly suggesting contributions from non-crustal sources for these metals, especially local and/or regional anthropogenic sources. Signi"cant contribu- tions are likely to originate from truck and automobile tra$c, electrometallurgical and electrochemical industries and municipal incinerators. These data provide with a unique snapshot of the situation which prevailed in the two valleys before the disaster which occurred on 24 March 1999 in the tunnel of Mont Blanc, which resulted into a massive fall of the tra$c in the Chamonix valley and a parallel rise in the tra$c in the Maurienne valley.  2000 Elsevier Science Ltd. All rights reserved. Keywords: Heavy metals; Snow; Alpine valleys; Mont Blanc tunnel; Local pollution 1. Introduction In the recent decades, there has been an increasing interest in heavy metals (Merian, 1991) in atmospheric precipitation and their possible environmental e!ects, see for instance Galloway et al. (1982), Munger and Eisen- reich (1983), Barrie et al. (1987), Barrie and Schemenauer (1989), Muhlbaier Dasch and Wol! (1989), Atteia (1994), Poissant et al. (1994, 1997), Riemann et al. (1996), Greg- urek et al. (1999) and Simonetti et al. (2000). This is to a large extent because the atmospheric wet deposition pathway of numerous heavy metals potentially toxic to humans and other organisms is of major signi"cance to many ecosystems. 1352-2310/00/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S 1 3 5 2 - 2 3 1 0 ( 0 0 ) 0 0 1 2 5 - 4