Screening for heavy metal accumulators amongst autochtonous plants in a polluted site in Italy Nadia Massa a , Flora Andreucci a , Monica Poli b , Maurizio Aceto a , Roberto Barbato a , Graziella Berta a,n a Universit  a del Piemonte Orientale, Dipartimento di Scienze dell’Ambiente e della Vita, Viale Teresa Michel, 11–15121 Alessandria, Italy b ARPA Piemonte, Polo Specialistico Microinquinanti, Spalto Marengo, 38–15121 Alessandria, Italy article info Article history: Received 8 March 2010 Received in revised form 21 August 2010 Accepted 24 August 2010 Available online 29 September 2010 Keywords: Heavy metals Multi-elemental contamination Autochthonous vegetation HM accumulator plants abstract The site around ACNA factory (Northern Italy) is characterized by multi-metal contamination, therefore it can be considered as a source of autochthonous plants able to tolerate or accumulate heavy metals (HMs). The hill A5, a waste dump of the chemical factory, was chosen as the study area, in order to assess the metal accumulation ability of the vegetation growing under HM stress. The plant species, biodiversity and health were related to the concentration of HMs in four areas of the hill A5, and to the metal accumulation in shoots and roots. Uptake of HMs occurred at different extent in the various plant species and differed according to the considered organ and metal. Polygonum aviculare hyperaccumu- lated Hg in the shoot suggesting its possible exploitation in phytoextraction. A number of species, that can be useful in phytoremediation plans, accumulated simultaneously more than two heavy metals both in the shoot and in the root. & 2010 Elsevier Inc. All rights reserved. 1. Introduction Heavy metals (HMs) represent one of the major ecological problems inducing detrimental effects on both human and environmental health. HMs are defined as metals with a density higher than 5 g cm 3 (Punz and Sieghardt, 1993); their main sources may be atmospheric or terrestrial and include mining, metal working industries, combustion of fossil fuels, disposal of ash residues from coal combustion, vehicular traffic and use of pesticides and fertilizers in agriculture (Clemens, 2006). Among HMs, a few such as Co, Mn, Fe, Cu, Se, Mo and Ni are essential elements, whereas Al, Cd, Cr, Hg, Pb are nonessential elements (Panda and Panda, 2002). In addition to these, metalloids as As are toxic for plants. Besides their toxicity, HMs are also quite persistent in the environment (Del Rio et al., 2002). Different chemical and physical methods have been developed in order to clean up HMs from the environment. Nevertheless, these techniques are costly from both an economic and an environmental point of view, and could negatively affect the chemical, physical and biological properties of the soil (Gamalero et al., 2009a). Phytoremediation is the use of plants able to tolerate pollutants for environmental cleanup. HM-tolerant plant can exclude, accumulate or hyperaccumulate and translocate HMs from the root to the shoot without showing stress symptoms (Del Rio et al., 2002). However, tolerance and (hyper)accumulation of HMs mainly occur in plant species characterized by small size and slow growth (Khan et al., 2000), therefore limiting their exploita- tion in phytoremediation. For this reason, much attention has recently been devoted to fast growing trees, even when they are not hyperaccumulators (Castiglione et al., 2009). In this context, polluted sites can be considered as a reservoir of native plants with the ability to tolerate or accumulate HMs to a different extent. Nevertheless, vegetational studies combined with plant chemical analyses are rarely performed (Pastor et al., 2007; Brunetti et al., 2009; Chehergani et al., 2009), therefore, the role of autochthonous flora in phytoremediation of HMs is a potential that has been, up to now, largely unexplored. ACNA (Aziende Chimiche Nazionali Associate—Associated National Chemical Companies) site is one of the 15 environmen- tally critical sites identified in Italy. This chemical industry was active in the production of explosives, dyes and their intermedi- ates from 1882 to 1999. High amounts of organic, such as aromatic chemicals, chlorinated benzenes, anilines, thiophenes and inorganic chemicals, in particular HMs, have been released by the industrial plant (D’Annibale et al., 2006) leading to a severe environmental impact. About 30 years ago, industrial wastes were dumped and covered with 1 m of non-polluted soil resulting in the construction of several mounds. Following diffusion pro- cesses, in time the cover soil became contaminated too, although at a lower degree than the core of the hill and still allowing spontaneous revegetation (Vallino et al., 2006). One of the hills, named A5, has been well characterized for the soil chemical and physical properties and has been considered as a model hill, representative of all the other dumps of the ACNA site Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ecoenv Ecotoxicology and Environmental Safety 0147-6513/$ - see front matter & 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.ecoenv.2010.08.032 n Corresponding author. Fax: + 39 131 360243. E-mail address: graziella.berta@mfn.unipmn.it (G. Berta). Ecotoxicology and Environmental Safety 73 (2010) 1988–1997