The use of tree-rings and foliage as an archive of volcanogenic cation deposition Sebastian F.L. Watt a, * ,1 , David M. Pyle a,1 , Tamsin A. Mather a,1 , Jason A. Day a , Alessandro Aiuppa b a Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK b CFTA e Dipt. Chimica e Fisica della Terra e Applicazioni alle Georisorse, Universita ` degli Studi di Palermo, Via Archirafi 36, 90123, Italy Received 1 April 2006; received in revised form 30 October 2006; accepted 3 November 2006 Dendrochemistry does not provide an archive of persistent volcanic activity. Abstract Tree cores (Pinus nigra ssp. laricio) and leaves (Castanea sativa) from the flanks of Mount Etna, Sicily were analysed by ICP-MS to inves- tigate whether volcanogenic cations within plant material provide an archive of a volcano’s temporal and spatial depositional influence. There is significant compositional variability both within and between trees, but no systematic dendrochemical correlation with periods of effusive, explosive or increased degassing activity. Dendrochemistry does not provide a record of persistent but fluctuating volcanic activity. Foliar levels of bioaccumulated cations correspond to modelled plume transport patterns, and map short-term volcanic fumigation. Around the flanks of the volcano foliar variation is greater for volatile cations (Cs, Cd, Pb) than for lithophilic cations (Ba, Sr), consistent with trace-metal supply from volcanic aerosol during quiescent periods. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Mount Etna; Volcanogenic cations; Tree-rings; Pinus nigra; Castanea sativa 1. Introduction Volcanic activity can affect vegetation in numerous direct and indirect ways, from local fumigation (Delmelle, 2003) to perturbations of radiation budgets and climate (Briffa et al., 1998; Gu et al., 2003). Understanding the environmental fate of volcanogenic trace elements may allow the develop- ment of reliable proxies for volcanic activity. For example, if a diagnostic chemical signature could be found in tree-rings linked to a causal volcanic event, this would be of great value for reconstructing records of past eruptions. Multi-elemental dendrochemical analysis (investigation of the composition of tree-rings) has been used extensively to study anthropogenic pollution, commonly using laser-ablation or solution inductively-coupled-plasma mass-spectrometry (ICP-MS) on individual or composited tree-rings (e.g., Hall et al., 1990; Hoffmann et al., 1994). Some authors have argued that dendrochemistry is unsuitable as a pollution archive (e.g., Bindler et al., 2004; Garbe-Scho ¨nberg et al., 1997; Zhang et al., 1995), while others conclude it has potential (e.g., Eklund, 1995; McClenahan et al., 1989) though perhaps only qualitatively (Bondietti et al., 1989). Dendrochemical methods have successfully recorded changing pollution levels on decadal to centennial timescales, and across large spatial scales (e.g., Padilla and Anderson, 2002; Tommasini et al., 2000; Watmough, 1999). If dendrochemistry may be used to investigate anthropo- genic pollution sources, then the method may reasonably be * Corresponding author. Tel.: þ44 01865 272000; fax: þ44 01865 272072. E-mail address: sebastian.watt@earth.ox.ac.uk (S.F.L. Watt). 1 Present address: Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK. 0269-7491/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2006.11.007 Environmental Pollution 148 (2007) 48e61 www.elsevier.com/locate/envpol