Ambient ozone phytotoxic potential over the Czech forests as assessed by AOT40

Abstract

© iForest -Biogeosciences and Forestry IntroductionAmbient ozone (O3) has been a widely studied air pollutant for many years due to its potential toxicity for all living organisms (Felzer et al. 2007, Cape 2008, Iriti & Faoro 2008. It is an important gas playing a key role in atmospheric chemistry (Seinfeldt & Pandis 1998). It contributes to the oxidative power of atmosphere which is essential for scavenging many pollutants from the air. Moreover, due to its absorption-radiation abilities, O3 is an important greenhouse gas (Singh & Fabian 2003, IPCC 2007. There are important mutual interactions between O3 and climate change (Isaksen 2003), which are not fully understood yet. The urgent need to address the knowledge gaps in interactions between air pollution, climate change and forests has been recently stressed (Serengil et al. 2011, Matyssek et al. 2012.Ozone represents one of the most prominent air pollution problems in Europe (De Leeuw & De Paus 2001, EEA 2010. Environmental O3 quality standards are exceeded over vast areas of Europe (Horálek et al. , 2009). Due to its phytotoxicity, O3 is still considered to be the most important air pollutant for forests (Paoletti et al. 2010). Due to the fact that O3 is a secondary pollutant formed from precursors during complex photochemical reactions and to the highly non-linear nature of O3 chemistry, it is and will be very difficult to decrease its ambient concentrations (Seinfeldt & Pandis 1998).Comparison of O3 levels with those measured a century ago indicates that current levels have increased by approximately two times. European measurements between 1850 and 1900 were found to be in the range of 17-23 ppb (Bojkov 1986). Modern day annual average background O3 concentrations over the mid-latitudes of the northern Hemisphere range between approximately 20-45 ppb, with variability influenced by geographic location, altitude and extent of anthropogenic impacts (Vingarzan 2004). Generally, three types of patterns in ambient O3 have been apparent recently: (1) an increase in the extent of O3 impact and the forest areas at risk; (2) a decrease in maximum 1-h O3 concentrations, at least in the northern hemisphere countries which have introduced O3 precursor control programs; and (3) an increase in background O3 concentrations over much of the world (Percy et al. 2003). It is not an easy task to assess the time trends of O3: the inter-annual variability is fairly high, so that long time series, which mostly are not available (Jonson et al. 2006), are needed to detect trends.In the Czech Republic (CR), ambient air pollution has been perceived as a major environmental problem since the 1950s, particularly due to extremely high emissions of SO2 and particulate matter from large powergenerating sources (Moldan & Schnoor 1992). Pollution in the form of surface O3 was recognized as an issue as late as in the 1990s. Its levels are regularly measured within the framework of a national ambient air quality network run by the Czech Hydrometeorological Institute (CHMI) since 1993. Fro...

Ozone phytotoxicity in the Western Carpathian Mountains in Slovakia

“…5,000 ppb h (Directive 2008/50/EC) indicate that rural highland sites of Europe are more vulnerable to health and environmental risks associated with perpetual O 3 exposure than urban lowland areas (Bičárová et al 2013). Concentration-based critical level (CLec) of AOT40 for forest ecosystems is regularly exceeded in almost whole territory of Slovakia (Pavlendová 2008) as well as in the Czech Republic (Hůnová & Schreiberová 2012;Hůnová et al 2016). At high-altitude stations, the background O 3 levels (chronic exposure) are higher, and higher O 3 concentrations are observed at night (Sicard et al 2009).…”

Ozone risk and foliar injury on Viburnum lantana L.: A meso-scale epidemiological study

“…Current exposure of vegetation to ozone in rural and forested areas in Europe often exceeds the concentration-based protection limits, expressed as ozone accumulated over a threshold of 40 ppb (AOT40) (Directive, 2008/50/EC;Hůnová and Schreiberová, 2012;Sicard et al, 2011;Staszewski et al, 2012;UN/ECE, 2004). The extent to which high ozone exposure results into an actual (and proportional) impact on vegetation has been widely discussed (Anav et al, 2011;Bussotti and Ferretti, 2009;Ferretti et al, 2007;Hůnová et al, 2011;Staszewski et al, 2012), as several factors (e.g., stomatal ozone uptake, defence mechanisms and adaptations to oxidative stress, multiple stresses) can modify plants' response (Fineschi and Loreto, 2012;Holopainen, 2011;Reich, 1987).…”

Structure, regeneration and growth of Scots pine (<i>Pinus sylvestris</i> L.) stands with respect to changing climate and environmental pollution

“…Decreasing trend of both ambient air pollution and deposition fluxes of sulphur and nitrogen is evident to the late 1990s, while these remain about the same since 2000 (Hůnová et al 2004;Hůnová et al 2014). Within the CR, the Třebechovicko microregion can be characterised as a medium polluted area both for sulphur and nitrogen (Hůnová 2001;Hůnová 2003), and also for ambient O 3 (Hůnová and Schreiberová 2012). Despite this and in accordance with other research results (Vacek and Podrázský 1994;Augustaitis et al 2007), SO 2 concentrations and N deposition in combination with extreme climate events causes sever defoliation in pine stands.…”