Abstract :
The atmosphere constitutes an important sink for many volatile and semivolatile organic compounds (Part II). Even non-volatile compounds may enter the troposphere due to incomplete burning of fuel and industrial, agricultural and traffic-related processes. Depending on vapour pressure, temperature and content of aerosol particles, chemicals prefer the free gas phase, the surface of the particles, or both compartments. Polar compounds (low Henry-coefficient) may dissolve in cloud-and fog droplets. Clearly, the prefered compartment influences the dominant abiotic degradation path. In this paper, a survey is given about the distribution and degradation pathways of chemicals in the troposphere. In the free gas phase of the troposphere, the reaction with OH-radicals is the dominant degradation path. In addition, the reactions with ozone and nitrate-radicals, and direct photochemical reactions also play a role in abiotic degradation.
