Berechnung zonaler und kompartimentbezogener Halbwertszeiten persistenter organischer Schadstoffe (POPs) in der Umwelt

The fate of POPs (persistent organic pollutants) has become the focus of growing national and international concern. The consensus among developed countries for restrictions on these substances results in large parts from knowledge that POPs have long half lives and can therefore move thousands of kilometres from the point of release. However, the assessment of these substances usually does not consider environmental parameters like temperature or precipitation, though they are significantly influencing their global persistence. Also the climatic zones where the chemicals are emitted have an enormous influence on their global persistence but are not taken into account for any assessments of their persistence. In this report a new computer model called "POPFATE" is presented that is able to estimate the global half life of organic compounds in the environment dependent on their use. According to the classification of Mackay POPFATE is a level 3 fugacity model. Distribution and degradation is calculated based an a multi compartmental steady state with non-equilibrium distribution. Whereas the original model of Mackay defines 6 phases including air, water, soil, sediment, suspended sediment and biota for the calculation of the global half life the concept described here has been extended to take into account the different climatic regions of the earth. The extended model is based on the categorisation of C. Troll (1). Each of the climatic zones is represented by 6 regional compartments influencing each other by exchange processes. The scenario parameters of the model describing the different climatic zones are mainly based on the work of Frank Wania (2). For the assessment of the ranges of global half-lives not only the mean climatic conditions, but also minimum and maximum values are considered.