Behaviour and fate of chemicals in aquatic systems

Behaviour of volatile substances in flowing waters

After being discharged into runoff ditches, organic chemicals are subjected, in manifold processes, to transformation, enrichment and elimination. Volatilisation from the water body is one of the major elimination processes by which specific chemicals are irreversibly removed from aquatic ecosystems. Studies have shown that quantification of volatilisation is subject to great uncertainties in the case of many substances.

In order to determine the volatilisation rate under natural conditions, however, parameters such as temperature, water and wind speed as well as the average water depth and the bed roughness have to be taken into consideration. All these parameters may have a substantial effect on volatilisation from natural waters. At present, the volatilisation of methyl tertiary-butyl ether (MTBE) is being examined by the Umweltbundesamt in cooperation with the Uni Osnabrück in controlled experiments at the FSA. Preliminary results have confirmed the relationship between volatilisation rate and flow speed.

Author: Dr. Jörg Klasmeier (Universität Osnabrück)