Tropospheric ozone in alpine forest sites: Air quality monitoring and statistical data analysis

Plants represent one of the major sinks for tropospheric ozone that, at hig h concentrations, can affect plants' physiological activity with consequent serious damage. A research project has been promoted by the Lombardy Found ation for the Environment to investigate the effects of air pollution on fo rest ecosystems. The areas of study are located on the southern slopes of t he Italian Alps in two valleys, only 10 km apart, selected because of their different plant injury: Val Gerola and Val Masino. Air quality (O-3, NOx, SOx, VOC) and meteorological parameters were monitored during four summer s easons (1994-97) using automatic sampling devices providing hourly mean val ues for each variable. Data analysis showed very different ambient ozone co ncentrations at the two sites, with average concentration values observed i n the more damaged valley (Val Gerola) twice those measured at the other si te. Multivariate data analyses have been used to interpret the observed dif ferences in long-term O-3 exposure between the two sites and to identify po ssible underlying processes.