Atmospheric residence time of carbonaceous particles and particulate pah-compounds

Abstract

Organic particulate material is almost entirely bound in accumulation mode particles (diameter 0,1 – 2 μm). Therefore elemental carbon has a long atmospheric residence time: Under Middle European conditions about 4,5 days. About 2/3 of airborne carbon is removed by wet removal processes. Polycyclic aromatic hydrocarbons (PAH's) were measured in particulate phase and rainwater. On account of gas phase contributions the lighter PAH-compounds are relatively more represented in rainwater. In the measured mass size distributions the less volatile PAH-compounds are more strictly bound in the accumulation mode. By introduction of the terms physical and chemical removal the residence times of some PAH-compounds are determined.