Microplastics and Persistent organic pollutants in moss samples from Germany

Introduction: Following their transport, atmospheric pollutants are deposited on the ground, on plants or on water. Depending on the substances involved, ecosystems can be adversely affected by the deposition of nutrients or pollutants. In order to be able to counteract the potential ecological risks through environmental policy measures, it is necessary to measure the atmospheric inputs of potentially harmful substances. For this reason, heavy metal concentrations in mosses used as accumulators of atmospherically deposited substances have been determined since 1990 for every five years at up to 7300 locations in up to 34 European countries. In 2005 nitrogen was added. Persistent organic compounds were determined for the first time in the European Moss Survey in 2010, in Germany firstly in the Moss Survey of 2015/2016. Microplastics were added to this group of substances for the 2020/2021 survey. Here, we are presenting results for microplastic and a variety of persistent organic pollutants (POP) from the 2020/2021 moss survey in Germany. Materials and Methods: Sampling was performed at 20 sites according to the recommendations of the Moss Survey Manual. Afterwards a sample preparation method was established for Thermo-Extraction-Desorption-GC-MS and RAMAN spectroscopy to analyze the microplastic concentration as well as number in the moss samples. Analyses for POPs were performed as described by Dreyer et al. 2018 with slight modifications. Overall, about 120 compounds (PAH, PCDD/F, PCB, PFAS, HBCD, PBB, PBDE, alternative halogenated flame retardants (HFR)) were analysed. Results: In all Moss samples microplastic were detected. The highest concentration in all samples was observed for polyethylene, followed by polyethylene terephthalate, polypropylene and styrene-butadiene and in one sample polystyrene. At the two sampling sites near the sea the highest microplastic concentrations were indicated, whereas no correlation with the other sampling location (urban, agriculture, forest) could be detected. PBB and indicator PCB were not observed above the LOQ in any sample. PFAS and dioxin-like PCBs were very rarely found above the LOQ. In contrast, certain PCDD/F, PAH, HBCD, PBDE and HFR were frequently observed. Current concentrations at sampling sites compared to those of sites that have also been investigated in 2015/2016 were in the same order of magnitude or declined. For HBCD, concentrations declined distinctly by a factor of up to 9. Conclusions: Microplastics and many POPs were observed in moss samples indicating their suitability to monitor atmospheric deposition of these substance groups by this bioindicator. Challenges exist for PBB, PCB or PFAS either because environmental concentrations are too low with respect to the LOQ or the pollutants’ environmental behavior limit accumulation in moss. Within the past five years, most POPs concentrations in moss samples from Germany stayed more or less the same or decreased.

Acknowledgements:

We are thankful to the German Environment Agency (Umweltbundesamt) for funding this study (FKZ 3720632010).

 References:

• UNECE ICP VEGETATION (2020) Heavy metals, nitrogen and POP in European mosses: 2020 survey monitoring manual. https://icpvegetation.ceh.ac.uk/sites/default/files/ICP%20Vegetation%20moss% 20monitoring %20manual %202020.pdf
• Dreyer A, Nickel S, Schröder W. et al. (2018). Environ. Sci. Eur. 30 (43): 1-14.