ELPOS - Criteria for persistence and long-range transport potential of pesticides and industrial chemicals
ELPOS runs since October 1999 and is financed by the German Federal Environmental Agency (FEA). The project's aim is to develop and investigate quantitative criteria for the long-range transport potential and persistence of organic chemicals.
The multimedia chemical fate model ELPOS-1.0 was used to calculate the overall persistence and the characteristic travel distance in air as descriptors for these criteria. Both descriptors account for the inter-media transfer and intra-media degradation and are independent of the amount emitted.
Physico-chemical and environmental degradation data of 65 currently used pesticides, 23 industrial chemicals, and 21 persistent organic pollutants were compiled. A sensitivity analysis showed that the sensitivity heavily depends on the characteristics of the chemicals and assumptions with respect to environmental conditions. The ranking of the chemicals can be affected if uncertainty of the parameters is taken into account, e.g. by using 90%-percentile instead of mean values.
The model was modified to account for temperature variations within a range of 5°C to 30°C. The overall residence time and the characteristic travel distance were found to be highly dependent on temperature. While the overall residence time always increases when temperature drops, the characteristic travel distance can increase or decrease depending on the characteristics of the substance. The characteristic travel distance was compared to observed spatial concentration gradients in the environment. Monitoring data of different PCB-congeners that were sampled along a south-north transect lead to the same chemical ranking as predicted by the characteristic travel distance.
Acknowledging the uncertainty and limitations of the underlying multimedia model, the overall residence time and the characteristic travel distance can serve for screening, ranking, and evaluation of substances concerning persistence and long-range transport potential. The assessment of the pesticides currently used identified candidates requiring further investigation and possibly management.