Pesticides in Particulate Matter (PM2.5) at the Rural Background Station Taunus Observatory, Germany

No other group of anthropogenic chemicals has been intentionally released on such a large scale as pesticides. Once in the environment, they can spread through various pathways (surface runoff, surface water, infiltration), which are already being analyzed in detail by a broad monitoring system and research projects. An often overlooked and inadequately quantified process is airborne transport. Through this transport route, pesticides can be transported over large distances and end up far away from the original emission source.

To investigate pesticide concentrations, particulate matter filter samples (PM_2.5) were collected continuously at the Taunus Observatory using a high-volume sampler. The measurement station is situated in the Taunus mountain range at an elevation of 826°m. The location is classified as a rural background station with no nearby urban or agricultural areas. The collected filters underwent extraction, enrichment, and analysis using a high-performance liquid chromatography system coupled to an ultra-high resolution (Orbitrap) mass spectrometer. Samples from April 2021 to May 2022 were analyzed in two-week increments. For a more detailed examination of diurnal cycles, two-week periods were analyzed with day and night resolution Additionally, backward trajectories were analyzed to identify potential sources.

By applying this technique, we successfully identified and quantified two fungicides (Pyrimethanil, Dimetomorph) and six different herbicides (e.g., Terbuthylazine, Prosulfocarb). The year-long data collection allowed the observation of seasonal variations in pesticide concentrations. The highest occurrences of pesticides were measured during spring, particularly in May. Pesticides used for winter crops showed highest concentrations in late autumn. The identified substances also included the herbicide Atrazine, which has been prohibited in Germany since 1991 and in the EU since 2002. Atrazine is typically used for corn and showed the typical patterns in its seasonality.

By applying this method, we were able to demonstrate that certain pesticides can be detected even at significant distances from potential sources. This makes it challenging to limit their occurrence and deposition to a specific area. Outstanding is the detection of Atrazine in aerosols, which has not been reported in Germany before.