Fine microplastics and nanoplastics in particulate matter samples from a high alpine environment

The steady high demand for plastics and the degradation of discarded materials have led to microplastics and nanoplastics becoming important pollutants in various environmental compartments. While the situation, e.g. in the marine environment, is frequently described in the literature, a focused research on ambient air and especially different size classes of airborne particulate matter is scarce. Still, airborne particles are of special importance, as they have high mobility and can be transported and distributed rapidly.

We analysed particulate matter samples of two size classes, PM₁ and PM₁₀ (particles with aerodynamic diameters up to 1 or 10 µm, respectively), using thermal desorption-proton transfer reaction-mass spectrometry (TD-PTR-MS) and determined and quantified different polymer types from the spectra using a previously described method [1]. Particulate matter was collected at the remote high alpine Global Atmosphere Watch station Sonnblick Observatory, Austria, at more than 3100 m above sea level on quartz-fibre filters. Sampling time was one week. The samples covered a summer period (June 2021 to September 2021) and a winter period (December 2021 to April 2022). The periods were selected to include samples with and without mineral dust occurrence to allow a comparison. For the 23 samples of PM₁ and PM₁₀, analysis was done in triplicates. Field blanks were also available. Several lab and field tests were performed to check possible influences during the storage of samples (use of different containers including plastics and aluminium foil) and sample preparation (addition of hydrogen peroxide).

Our evaluations include the determination of six common types of plastics (PET, PE, PP/PPC, PS, PVC, tire wear) in both fractions and seasonal differences in their relative contributions. The most abundant plastic types were PET, PE and PP/PPC. Overall polymer concentrations reached up to 125 ng/m³. Field blanks showed comparably low presence of PET. We further compare the relative contributions of the summer and winter periods depending on the occurrence of mineral dust.

 

[1] Materić, D. et al., Micro- and Nanoplastics in Alpine Snow: A New Method for Chemical Identification and (Semi)Quantification in the Nanogram Range. Environmental science & technology 2020, 54(4), 2353-2359.