Spatial distribution of atmospheric microplastics in bulk-deposition of urban and rural environments - A one-year follow-up study in northern Germany

Malin Klein; Benjamin Bechtel; Torben Brecht; Elke Kerstin Fischer

doi:10.1016/j.scitotenv.2023.165923

Spatial distribution of atmospheric microplastics in bulk-deposition of urban and rural environments - A one-year follow-up study in northern Germany

Sci Total Environ. 2023 Nov 25:901:165923. doi: 10.1016/j.scitotenv.2023.165923. Epub 2023 Jul 31.

Authors

Malin Klein¹, Benjamin Bechtel², Torben Brecht¹, Elke Kerstin Fischer³

Affiliations

¹ CEN - Center for Earth System Research and Sustainability, University of Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany.
² Urban Climate Lab, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany.
³ CEN - Center for Earth System Research and Sustainability, University of Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany. Electronic address: elke.fischer@uni-hamburg.de.

PMID: 37532052
DOI: 10.1016/j.scitotenv.2023.165923

Abstract

Atmospheric microplastic deposition rates play a crucial role for calculating the input of microplastics in the environment and to further understand pollution patterns. In this study, the spatial and temporal distribution of atmospheric microplastic particles in urban and rural areas of Northern Germany was investigated. Therefore, eleven structurally diverse locations in Hamburg and Mecklenburg-Western Pomerania were equipped with bulk-deposition samplers in triplicates and sampled monthly between August 2019 and July 2020. The resulting 306 samples were treated with hydrogen peroxide (30 %) and sodium hypochlorite (6-14 %) to digest biological organic matter. The filters were subsequently stained with the lipophilic dye Nile Red and underwent visual microplastic identification via fluorescence microscopy. Fragments and fibers were quantified down to a cut-off size of 10 μm. The polymer composition of microplastic particles was investigated along a subset of particles via μ-Raman spectroscopy. The microplastic deposition rate for Northern Germany (89 ± 61 MP/m²/day) is in the same order of magnitude as those reported by previous studies. Significant differences in microplastic deposition rates were found between urban and rural sampling sites. Population density was identified as an important factor for greater amounts of microplastics and higher shares of fibers in urban samples. Special attention was given to the canopy cover at two forested sampling sites and an influence of the comb-out effect on atmospheric microplastic deposition was detected.

Keywords: Atmospheric deposition; Comb-out effect; MP pollution; Nile Red; Terrestrial ecosystems; μ-Raman.