Scientists' Contributions  
   

Monitoring and Biomonitoring Ambient Ozone in the Greek Mainland

C. J. Saitanis*, M.G. Karandinos, D. Lekkas, D. Katsaras, A. Riga-Karandinos and G. Arapis

Laboratory of Ecology and Environmental Sciences, Agricultural University of Athens, Iera Odos 75, Athens, 11855 Greece (*saitanis@aua.gr)

    Although ozone is recognized to be the most widespread phytotoxic air pollutant, especially in southern European countries, extremely little is known about its occurrence in the Greek mainland. We report here the results of instrumental recording and biomonitoring of ozone at several rural areas during the year 2000. Instrumental records concern the following rural areas: the Mesogia plane - Attika [Spata and Markopoulo from May 1 to Aug 31 and Artemis (Loutsa) from Aug. 11 to Aug. 31] the greater rural area of Corinth [Bogdani hill - Athikia (Jun. 18 - Aug. 1), the Astronomical Observatory of Krionerion (Aug. 6 - Aug. 28) and Kiato (Aug. 29 - Sep. 21)]. Biomonitoring was conducted at all the above-mentioned regions and at many other places (including, Salamis island, Aliartos, Kalamata, Argos, Volos, Pelion Mountain, greater region of Karditsa, etc) during the same year. Moreover, instrumental records of ozone concentrations (Jun. 18 - Aug 31) and biomonitoring were conducted in the highly polluted metropolitan area of Athens, for comparative purpose. Plants of Bel-W3 (very sensitive to ozone) and Zichnomirodata (KK6/5) tobacco (Nicotiana tabaccum L.) (ozone sensitive) varieties were used in biomonitoring. The diurnal patterns of stomatal conductance of Bel-W3, grape vines (Vitis vinifera) and Allepo pine (Pinus halepensis Mill.) trees were also measured and compared to the diurnal pattern of ozone concentrations.

    The ozone levels, during the daylight hours, were found to range from 30-80 ppb, which is considered high enough to affect at least sensitive cultivated plant species and probably forest trees. The AOT40s in most of the monitored regions were considered phytotoxic. The average daily AOT40 was 193 in Athens, 158 in Spata, 178 in Markopoulo, 384 in Artemis, 212 at Bogdani hill, 192 at the astronomical observatory and 47 in Kiato. At the locations of low altitude the ozone concentrations exhibited the usual diurnal patterns (maximizing during the midday and early afternoon hours and minimizing during the night hours). However, at the Astronomical Obs. of Krionerion, which is characterized by high elevation (~950 m), ozone remained constant during both daylight and night hours. Moreover, it was found that in most of the rural areas ozone maximized 1-3 hours later in comparison to Athens.

    The bioindicator plants of Bel-W3 and Zichnomirodata exhibited the characteristic ozone induced symptoms at most of the biomonitored places. The extent of symptoms varied spatially and temporally.

    The diurnal pattern of stomatal conductance was found to maximize during the morning and early midday hours, suggesting a much higher probability for O3 absorption by the vegetation during these hours than in the afternoon hours.

    Synoptically, our investigations suggest that ozone occurs in the Greek mainland at such levels that should be considered phytotoxic at least for sensitive species. It also suggests that stomatal conductance should be taken into account in investigations of ozone phytotoxicity.

       
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