Phenols and Nitrated Phenols in Clouds at Mount Brocken

Two phenols and four nitrophenols have been determined in the gas and liquid phase of clouds during a field campaign in May 1994 at Mount Brocken (Germany). If the total amount in both phases is considered, 2-nitrophenol is the dominant compound which is mainly present in the gas phase while 4-nitrophenol is much more abundant in the liquid phase, which reflects the differences in the distribution constants. The experimental data suggest that mononitrophenols may partially originate from automobile exhaust while dinitrophenols are almost completely formed by atmospheric reactions. Furthermore, comparison of the concentration of dinitrophenols and the extent to which air masses are transported in clouds indicates that these compounds are mainly formed in cloud droplets.