|
(M/EH097) An Improved Concept of Air/Soil Partitioning for Global Multimedia Fate Models. Wegmann, Fabio1, Scheringer, Martin1, Goss, Kai2, Schwarzenbach, Rene2, Hungerbühler, Konrad1, 1 2 ABSTRACT- Current multimedia fate models describe the equilibrium distribution of substances between air and soil through a single process: absorption from air into the soil organic matter, using the KOA as the governing distribution coefficient. However, there are experimental data for adsorption onto mineral surfaces which show that this adsorption process is not negligible if the soil surface is dry and the organic carbon content not too high. Therefore, adsorption onto mineral surfaces can be of major importance for the global fate of organic compounds, especially in dry areas such as deserts and steppes, where a large amount of mineral surface is available for adsorption. The existing data and concepts [1] enable us to predict adsorption coefficients for organic compounds from purified air to mineral surfaces. However, the background concentration of organic compounds in natural air may be high enough to have an influence on the adsorption equilibrium of single compounds. Hence, one goal of our work is to check this influence by using ambient air as background in our adsorption experiments on an inverse gas chromatography unit. The insights from these experiments shall allow us to refine the concept and investigate the effect of adsorption onto mineral surfaces in global multimedia fate models. The refined concept will be included in a model for the global circulation of persistent organic chemicals [2]. [1] K.U. Goss, R.P. Schwarzenbach, Environ. Sci. Technol., 33 (1999), 4073-4078 [2] M. Scheringer, F. Wegmann, K. Fenner, K. Hungerbühler, Environ. Sci. Technol. 34 (2000), 1842-1850. Key words: multimedia model, air/soil partitioning, adsorption, ambient air |
