Abstract
Field studies have shown that photochemically generated ozone from O sub(3) precursors accumulate slowly and are transported to rural areas, where concentrations can exceed natural background levels. Ozone and nitric oxide concentrations were measured for 1 yr at a mountainous site in northwestern Turkey, and contributing source regions were determined through wind-sector analysis. Results indicated a mean 1-h average concentration of 29 ppb, with the highest at 98 ppb. A summer maximum and winter minimum were found, with late spring summer occurrences of peak concentrations. Diurnal variations showed a late-afternoon O sub(3) peak in summer, which then shifted toward earlier hours and become less pronounced in winter. Nitric oxide stayed constant throughout the day, but nitrogen dioxide and sulfur dioxide showed substantial diurnal variations. Highest O sub(3), NO sub(2), and SO sub(2) concentrations were associated with wind sectors between north and northeast, and south and southwest, which indicated the sources to be the city of Bursa and a thermal power plant, respectively.