Please cite this article in press as: K. Koci ´ c, et al., Trees as natural barriers against heavy metal pollution and their role in the protection of cultural heritage, Journal of Cultural Heritage (2013), http://dx.doi.org/10.1016/j.culher.2013.05.001 ARTICLE IN PRESS G Model CULHER-2774; No. of Pages 7 Journal of Cultural Heritage xxx (2013) xxx–xxx Available online at www.sciencedirect.com Original article Trees as natural barriers against heavy metal pollution and their role in the protection of cultural heritage Katarina Koci ´ c a,∗ , Tijana Spasi ´ c b , Mira Aniˇ ci´ c Uroˇ sevi ´ c c , Milica Tomaˇ sevi ´ c c a National Library of Serbia, Belgrade, Serbia b Ministry of Energy, Development and Environmental Protection, Belgrade, Serbia c Institute of Physics, University of Belgrade, Belgrade, Serbia a r t i c l e i n f o Article history: Received 13 December 2012 Accepted 6 May 2013 Available online xxx Keywords: Degradation Urban air pollution Tree leaves bioaccumulation Heavy metals SEM-EDAX Natural barrier Protection Cultural heritage a b s t r a c t Leaves of common deciduous trees: the horse chestnut (Aesculus hippocastanum) and linden (Tilia spp.) from the park, near one of the most important cultural institutions, the National Library of Serbia, were studied as bioaccumulators of heavy metal (Cr, Fe, Ni, Zn, Pb, Cu, V, As and Cd) air pollution. The leaf samples were collected from the urban park exposed to the exhaust of heavy traffic. The May–September heavy metal accumulation in the leaves, and their temporal trends, were assayed in a multi-year period (2002–2006). Comparing the obtained concentration of the investigated elements from the beginning to the end of growing seasons, a significant rate of accumulation was determined for a majority of measured elements, and it was concluded that these tree species (horse chestnut and linden) can be used as bioac- cumulators of the investigated heavy metals. The SEM-EDAX analysis of individual particles deposited on the leaves showed that the 50–60% belong to a class of fine particles (D < 2 m), mainly of anthropogenic origin. Thus, the investigated tree species could be grown as a natural barrier against urban air pollution in the vicinity of libraries, museums and other buildings for cultural heritage storage. © 2013 Elsevier Masson SAS. All rights reserved. 1. Research aims Knowing that shelterbelts are used to modify local environ- mental conditions and reduce the effects of emitted pollutants (industrial zones, dumps), it could be useful to assess an ability of tree species in urban areas to be used in shelterbelts around objects of cultural heritage against the urban air pollution. Since the building of the National Library of Serbia is located in the heavy traffic area of Belgrade, the aim of this study was to eval- uate the applying of common urban tree species – horse chestnut and linden – as a natural barrier against particulate/heavy metal air pollution. Thus, leaves of these tree species were tested for bioaccumulation of the selected heavy metals, present at low con- centrations in air, but with high potential for human health risks and degradation of cultural heritage. Additionally, particulate cap- ture and their physico-chemical characterization were observed on the examined tree leaves. ∗ Corresponding author. E-mail addresses: katarina.kocic@nb.rs (K. Koci ´ c), tijana.spasic@merz.gov.rs (T. Spasi ´ c), mira.anicic@ipb.ac.rs (M.A. Uroˇ sevi ´ c), milica.tomasevic@ipb.ac.rs (M. Tomaˇ sevi ´ c). 2. Introduction Air pollution effects and environmental conditions are main causes of degradation of cultural heritage [1]. The process of degra- dation can be defined as a progressive and cumulative process of materials that respond differently to the values given by environ- mental variables and their changes [2]. Particulate matter (PM) and some gaseous pollutants, such as O 3 , NO x and SO 2 , have been recognized as key environmental prob- lem in many cities around the world. Particulates in the air are a mixture of solid and liquid droplets that vary in size, morphol- ogy, and chemical composition. Residence time of particles in the air depends, first of all, on their size, and mainly varies from sev- eral minutes or days for particles over 1 m, while approximately 30–40 days for particles smaller than 0.5 m [3]. As constituents of airborne particles, heavy metals and other trace elements are transferred to the biosphere. Nowadays, more than 40 chemical elements are measured in atmospheric particulate matter sam- ples. About 70% of the mass of As, Pb, Zn and Cd are emitted to the atmosphere as fine particles with diameter less than 0.95 m [4,5]. Road traffic contributes significantly to air pollution in urban areas, generating PMs and heavy metals around roads [5]. The results for the daily mass concentrations of PM 10 (68.4 g m -3 ) and PM 2.5 (61.4 g m -3 ) in the Belgrade urban area during 2003–2005 1296-2074/$ – see front matter © 2013 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.culher.2013.05.001