The measurement of chemical persistence in lakes using benchmarking techniques

Sammanfattning: The persistence of a chemical that indicates resistance to degradation is one of the core criteria for exposure and hazard assessment of chemicals. However, it is rarely measured in the real environment because of the lack of appropriate methods. The potential of a benchmarking approach to estimate the persistence of organic chemicals in lakes was evaluated by means of a simple multi-media box model. The application of the benchmarking approach to quantify key environmental properties affecting chemical fate was also introduced and applied to: 1. the overall air-water mass transfer coefficient; 2. the sediment burial rate. To know in which cases which system property needs to be quantified, the model was run to identify the dominant physical removal processes for a set of hypothetical chemicals. The maximum value of the persistence in lakes that can be measured due to the limitation of several uncertainties such as the precision of the analysis methods was presented and found to depend on both chemical properties and lake characteristics. By combining benchmarking with a good sampling strategy and analysis methods, it is possible to measure the persistence in a lake of the order of a month or longer for chemicals in large portions of the partitioning space. A framework of how to select an appropriate lake system to assess the persistence of chemicals was introduced.