Occurrence and Fate of Organic Micropollutants in the Environment: Regional Mass Balances and Source Apportioning in Surface Waters Based on Laboratory Incubation Studies in Soil and Water, Monitoring, and Computer Modeling

Abstract

Research activities at the plant protection chemistry group of the Federal Research Station in Wädenswil, Switzerland, are primarily focused on the environmental behavior of pesticides and, in some cases, other organic micropollutants. Many old and modern pesticides are chiral and there is growing interest from registration authorities and companies in the different biological activity and environmental behavior and impact of individual stereoisomers. The environmental behavior of chiral pesticides is thus one of our main areas of research. We use monitoring data (e.g. surface waters, wastewater) to establish regional mass balances of a chemical (e.g. in the catchment area of a lake). Mass balances often indicate possible sources and presence of elimination processes such as (bio)degradation, sorption/sedimentation, and volatilization. Elimination processes are further investigated in model systems in the laboratory, including batch incubations in soil and water under different regimes (light/dark, sterile/non-sterile), to distinguish between biotic and abiotic (photolysis, hydrolysis) processes. Environmental models are then used to rationalize the chemodynamics of micropollutants in natural systems, integrating data from monitoring and model systems. In some cases, it is possible to use the data for source apportioning of pollutants in the environment, and for monitoring (or prediction) of the effectiveness of pollution prevention measures. In the following report, three examples will be presented which illustrate the general approach outlined above to study the environmental occurrence and behavior of organic micropollutants. These examples include the chiral herbicide mecoprop and the chiral pharmaceutical drug ibuprofen, as well as the ubiquitous natural compound caffeine.