Active Biomonitoring of Ecotoxicological Effects from Tropospheric Ozone Impact on Representative Tree Species

Abstract

In order to access the occurrence of phytotoxic ozone effect at urban and rural sites, two-year old seedlings of ozone-sensitive (Quercus robur L.) and ozone-tolerant (Quercus rubra Michx.) tree species were observed. The seedlings were exposed to ambient air for three month period (June-August), 2008 in two monitoring sites -in the city of Sofia, beside a big road with dense traffic, and in the Plana Mountain. The relationship between ozone pollution and ozone-induced effects on leaf area index and water regime were examined. The results for leaf area parameters are too preliminary due to the short period of the examinations. Strong ozone impact was found at the urban site with higher ozone exposure, corresponding to transpiration rate. The ozone induced alterations in physiological activity of tree seedlings may serve as yearly indication for leaf injuries, which could be expected in the further studies. The obtained results are discussed in relation to AOT40 index.