Microplastic Deposition Flux in Vienna

Microplastic Deposition Flux in Vienna

Atmospheric microplastic deposition presents an important pathway for plastic pollution in all ecosystems, yet quantitative data on atmospheric deposition fluxes in urban areas remain sparse. This study quantifies atmospheric microplastic deposition fluxes in Vienna using a combined observational and modelling approach. Specifically, atmospheric deposition is measured using a wet and dry passive sampler, allowing separate calculations of wet and dry deposition fluxes. Samples are collected daily over one-week campaigns during winter, spring, and autumn to enable the calculation of daily deposition fluxes and evaluation of seasonal variability. These samples are processed using a recently developed technique called oleo extraction and are then analysed via Fourier transform infrared spectroscopy and microscopy (Micro-FT-IR) for particle identification and classification. Additionally, wind speed and direction are used in correlation analyses against deposition to assess the influence of local sources, whilst FLEXPART Lagrangian dispersion modelling is applied to evaluate the contribution of long-range atmospheric transport. Preliminary results from the pilot study and autumn sampling campaign have confirmed the identification of microplastic particles in the deposition fluxes (e.g. 40-50 µm fragments of polypropylene and polyvinyl chloride). Alongside this, the preliminary analysis shows in several samples a dominant fraction of dark particles below 10µm in diameter, occasionally detected by the Micro-FT-IR as rubber. Due to their size, morphology and colour, we suspect them to be tire wear particles. This would confirm the dominant role of traffic related sources on the microplastic particles detected in urban air. In contrast to previous studies, the analysis of the first collected samples shows a very low percentage of plastic microfibers.  These findings highlight the importance of gaining microplastic deposition fluxes in urban environments, along with their dominant source processes.