ABSTRACT
In the atmosphere, carbonaceous particles primarily derive from various combustion processes, and over the last century their concentrations in urban areas have undergone a drastic, quasi-exponential increase. All combustion processes produce abundant amounts of carbonaceous species, which contain both organic and elemental carbon. While the atmospheric concentrations of sulphur dioxide (the main pollutant responsible for sulphation) have been drastically reduced in recent years, the air content of carbonaceous particles has continued to rise. The underlying premise of the EC Project CARAMEL is that, although important advances have been made in the knowledge of black crust composition and formation, attention has mainly centred on the role of atmospheric sulphur and gypsum formation, while data on the ubiquitous and abundant carbon particles remain rather scarce (Del Monte et al. 1981). In addition, various atmospheric combustion sources have been identified as responsible for the presence of carbon particles in black crusts (Ausset et al. 1998).
