Micro- and Nanoplastics in Alpine Snow: A New Method for Chemical Identification and (Semi)Quantification in the Nanogram Range

Abstract

We present a new method for chemical characterization of micro- and nanoplastics based on thermal desorption–proton transfer reaction–mass spectrometry. The detection limit for polystyrene (PS) obtained is <1 ng of the compound present in a sample, which results in 100 times better sensitivity than those of previously reported by other methods. This allows us to use small volumes of samples (1 mL) and to carry out experiments without a preconcentration step. Unique features in the high-resolution mass spectrum of different plastic polymers make this approach suitable for fingerprinting, even when the samples contain mixtures of other organic compounds. Accordingly, we got a positive fingerprint of PS when just 10 ng of the polymer was present within the dissolved organic matter of snow. Multiple types of microplastics (polyethylene terephthalate (PET), polyvinyl chloride, and polypropylene carbonate), were identified in a snowpit from the Austrian Alps; however, only PET was detected in the nanometer range for both snowpit and surface snow samples. This is in accordance with other publications showing that the dominant form of airborne microplastics is PET fibers. The presence of nanoplastics in high-altitude snow indicates airborne transport of plastic pollution with environmental and health consequences yet to be understood.

Airborne microplastic particles detected in the remote marine atmosphere

“…Our findings indicate a new possible source and formation mechanism for AMP, different to those found for the terrestrial and coastal AMP detected to date 13,[22][23][24][25][26][27][28][29][30][31][32][33] . We have evidence from the open ocean, which suggest that AMP is emitted from the seawater into the atmosphere through wind related processes.…”

“…We postulate that these results underestimate the actual AMP concentration in the marine atmosphere due to the current technical challenges, which did not allow us to analyze airborne microplastic particles smaller than 5 µm (see "Methods" section for more details). Moreover, nanoplastic particles (<1 µm) were only very recently identified in the environment at the single particle level 28 , due to methodological limitations in nanoplastic collection and detection 44,53 . In a typical marine aerosol size distribution, the diameter range between 10 nm-1 µm constitutes >99% of the total marine airborne particle concentration 52 , as was also measured during the R/V Tara Pacific expedition 38 (see Table 1 and Fig.…”

“…Estimates of recent years suggest that ∼5.25 trillion plastic fragments are currently floating on the oceans' surface 21 . Airborne microplastic particles (AMP) from terrestrial origins were found in both polluted and remote areas over land, as well as in coastal regions, ranging from micron to mm scales, and can travel tens of kilometers 12,13,[22][23][24][25][26][27][28][29][30][31][32][33] . However, despite the overwhelming amounts of marine MP and their effect on the marine environment, atmospheric microplastic particles over the ocean are given little attention 13 .…”

Atmospheric transport is a major pathway of microplastics to remote regions

“…Since the majority of the fibres was <25 μm size, these number concentrations can be converted to mass concentrations of 3.4 ± 2.8 and 3.6 ± 0.80 ng g −1 in Svalbard and Bavaria, respectively. Materić et al 65 reported PET (polyethylene terephthalate), PPC (polypropylene carbonate) and PVC (polyvinyl chloride) concentrations in Alpine snow of 5.6-23, 11-16 and 6.9 ± 0.2 ng g −1 , respectively. These concentrations are ~100 times higher than those estimated here for TWPs and BWPs in snow (Fig.…”

Atmospheric Transport, a Major Pathway of Microplastics to Remote Regions

“…Since the majority of the fibers was <25 μm size, these number concentrations can be converted to mass concentrations of 3.4±2.8 ng g -1 and 3.6±0.80 ng g -1 in Svalbard and Bavaria, respectively. Materic et al 51 reported PET, PPC and PVC concentrations in Alpine snow of 5.6-23 ng g -1 , 11-16 ng g -1 and 6.9±0.2 ng g -1 , respectively. These concentrations are about 100 times higher than those estimated here for TWPs and BWPs in snow (see Fig.…”