Ozone phytotoxic potential with regard to fragments of the Atlantic Semi-deciduous Forest downwind of Sao Paulo, Brazil

In the Metropolitan Region of Campinas (MRC), Brazil, high levels of primary pollutants contribute to ozone (O-3) formation. However, little is known regarding the O-3 effects in the tropics. Objectives in this study were to characterize the present levels of O-3 pollution and to evaluate the relevance of current concentration-based indices for assessing the phytotoxic potential of O-3. Changes in O-3 concentrations and precursors at 5 monitoring stations within towns of MRC were analyzed. The daily O-3 profile was typical for urban sites and showed little yearly variation. Given the permanently foliated forest canopy, yearly rather than seasonal 03 indices were thus more appropriate for estimating the effective ozone dose. With yearly SUM00, SUM60 and AOT40 of 156, 16 and 14 ppm h and confirmed by evidence of 03 injury in foliage, oxidative stress in the MRC has reached levels high enough to affect trees from the Atlantic Semi-deciduous Forest. (C) 2014 Elsevier Ltd. All rights reserved. (AU)