Wind tunnel simulation of microplastics transport in atmospheric boundary-layer flows

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Plastics are an inseparable component of modern daily life, present in the fibers of our clothing and the devices we use. Capable of being molded, extruded or blown to form objects of almost any shape or size, they are inexpensive to produce, largely resistant to corrosion or biodegradation, good insulators, and lightweight yet relatively strong. All plastics are manufactured on land, where potentially hazardous compounds like stabilizers or colourants may be added. Whether produced in lengths under 5 mm or reduced to this size via weathering within the environment, microplastic particles can be transported by wind and running water over very long distances within Earth's atmosphere and surface waters to accumulate in deep oceans and even in remote polar regions. For over 80 years, Earth scientists have used wind tunnels in combination with numerical schemes to understand the physics of particle transport by wind and to predict the atmospheric conditions under which transport is initiated and deposition occurs. However, the properties of manmade plastic particles are far more complex than sedimentary particles. Researchers from Canada and the UK recently carried out experiments in an environmental wind tunnel at Trent University (TEWT) which suggest that microplastic fibers are preferentially transported as compared to quartz particles, travelling with higher frequency and over greater distances than expected. In continued collaboration, we will use high-speed photography and materials science techniques to assess microplastic abrasion and motion in three-phase flow experiments carried out in abrasion chambers at Loughborough and the wind tunnel at Trent. The overarching goal is to refine and quantify our understanding of microplastic behaviour during atmospheric transport and to improve model prediction. Workers from the UK have recently received a Natural Environment Research Council grant to support this project. This proposal seeks Alliance funding from NSERC that will allow TEWT researchers and trainees to fully participate in this multidisciplinary international collaboration and to expand the scope of the work to improve integration between the experimental approaches.