Relationships Between Leaf Exposure Time to Air Pollution and Metal and Particulate Matter Accumulation for Holm Oak Leaves Valeria Memoli & Francesco Esposito & Lucia Santorufo & Speranza Claudia Panico & Marco Trifuoggi & Gabriella Di Natale & Giulia Maisto Received: 2 July 2020 /Accepted: 2 October 2020 /Published online: 12 October 2020 # Springer Nature Switzerland AG 2020 Abstract Plants play a fundamental role by intercepting air particulate matter (PM) and improving air quality. The link between the accumulation of pol- lutants and the leaf exposure time to air pollution re- mains unclear as it depends on different factors. The aim of this study is to test if the metal and PM accumulation in holm oak leaf is linked to exposure time to air pollu- tion. For this study, 1- (1y) and 2-year (2y) old holm oak leaves were sampled in an urban area near Naples. Those leaves were analyzed to measure the amount of particulate matter (PM 2.5–10 and PM >10 ) and the Cr, Cu, Mn, and Ni metal concentrations. The results displayed that leaf Cr, Cu, and Mn accumulation are linked to exposure time, whereas leaf PM deposit was not directly linked to the exposure time. PM deposit on leaves could be influenced by rainfall events or by the saturation of leaves’ surface. Keywords Air quality . Biomonitoring . Leaf element accumulation . Leaf PM deposit . Leaf age 1 Introduction Intensive urbanization during recent decades has con- tributed to increase anthropogenic pressures on the en- vironment. Industries, domestic heating, and vehicular traffic are the major causes of particulate matter (PM) and pollutant emissions into the air in urban areas (De Nicola et al. 2015; Esposito et al. 2018). Particulate matter is a heterogeneous solid-liquid mixture, contain- ing sometimes toxic substances and transported in the atmosphere, sometimes over long distances (WHO 2003). While coarse particulate matter can derive both from anthropogenic and natural sources (i.e., agricultur- al, mining activities, desert dust, or sea spray), fine particulate matter mainly derives from anthropogenic sources (i.e., domestic emissions, industrial activities, and road traffic) (Seinfeld and Pandis 1998). In the urban environment, PM can be rich in other compounds, such as polycyclic aromatic hydrocarbons and heavy metals (Popek et al. 2012), which direct threat to human health (United Nations 2014). In these envi- ronments, urban vegetation, through leaf accumulation, can filter atmospheric particulate matter out of the air and contribute to air quality improvement (Bealey et al. 2007; Nowak et al. 2006, 2013). Holm oak (Quercus Water Air Soil Pollut (2020) 231: 529 https://doi.org/10.1007/s11270-020-04894-3 Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11270-020-04894-3) contains supplementary material, which is available to authorized users. V. Memoli : F. Esposito : L. Santorufo (*) : S. C. Panico : G. Maisto Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Cinthia, 80126 Naples, Italy e-mail: lucia.santorufo@unina.it M. Trifuoggi Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Via Cinthia, 80126 Naples, Italy G. Di Natale CeSMA - CeSMA - Centro Servizi Metrologici e Tecnologici Avanzati, Università degli Studi di Napoli Federico II, Corso Nicolangelo Protopisani, 80146 Naples, Italy