RESEARCH ARTICLE Spatial and temporal trends of ozone distribution in the Jizerské hory Mountains of the Czech Republic Iva Hůnová 1,2 & Petra Stoklasová 1,2 & Jana Schovánková 1 & Alena Kulasová 3 Received: 15 June 2015 /Accepted: 14 August 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract We present results of the 5-year monitoring of am- bient O 3 concentrations in a Central European medium alti- tude mountain forested area. O 3 levels were measured at 11 sites between 714 and 1000 m a.s.l. in 2006–2010 vegetation seasons using Ogawa diffusive samplers. Our results reveal that O 3 exposure in the Jizerské hory Mts. was relatively high and comparable with polluted sites in Southern Europe and in higher altitudes. O 3 concentrations differed significantly be- tween individual sites and in individual years. O 3 concentra- tions showed clear dependence on altitude at sites with similar aspect. Its gradient for the entire 5-year period under review equaled 3.5 ppb/100 m of altitude, ranging between nearly 5 ppb/100 m of altitude in 2006 and nearly 3 ppb/100 m of altitude in 2010. O 3 concentrations at the site with northern aspect were consistently significantly lower than at the site at similar altitude with southern aspect. O 3 concentrations mea- sured at the forest edge were consistently lower than those measured at the same site but at the forest clearing. It is evident that the macro-setting of the O 3 monitoring site is crucial for obtaining reliable results with high repre- sentativeness for the area. Keywords Ambient ozone . Diffusive samplers . Spatial and temporal variations Introduction Ambient ozone (O 3 ) is a pollutant well known for its effects on vegetation (e.g., Agrawal and Agrawal 1999; Roschina and Roschina 2003). This is particularly true in mountain ecosys- tems, where O 3 concentrations are high, species are sensitive to stress, and water availability is generally not limited, en- abling nonrestricted O 3 flux from ambient air to plants through open stomata (Matyssek et al. 2007). That is why monitoring efforts are often focused on mountain areas (e.g., Puxbaum et al. 1991; Aneja et al. 1994; Bytnerowicz et al. 2007). Despite 40 years of control in North America, Japan, and Europe, O 3 remains a serious air pollution problem (Royal Society 2008). Increase in the background O 3 recorded at many places (Vingarzan 2004) has not yet been fully under- stood (Jonson et al. 2006). The trend of increasing background O 3 is very important as it greatly degrades the benefit of the reductions in peak O 3 levels and makes it a hemispherical issue (Derwent et al. 2004). Moreover, O 3 is involved in nu- merous interactions with other gases and aerosol in atmo- sphere, and through ecosystem interactions with nitrogen and carbon cycles, and climate change (Simpson et al. 2014). On a long-term basis, O 3 represents one of the most important environmental problems in Europe (De Leeuw and De Paus 2001; EEA 2010). Due to its phytotoxicity, O 3 is still considered to be the most important air pollutant for forests Responsible editor: Gerhard Lammel Highlights • We measured O 3 in a Central European medium altitude forested area in 2006–2010. • O 3 concentrations were high, comparable with polluted sites in Southern Europe. • O 3 concentrations differed significantly between individual sites. • O 3 concentrations differed significantly between individual years. • Altitude, aspect, and proximity to forest were the factors driving the O 3 levels. * Iva Hůnová hunova@chmi.cz 1 Czech Hydrometeorological Institute, Prague, Czech Republic 2 Faculty of Science, Institute for Environmental Studies, Charles University in Prague, Prague, Czech Republic 3 T.G.Masaryk Water Research Institute, Prague, Czech Republic Environ Sci Pollut Res DOI 10.1007/s11356-015-5258-0