Clay mineral-based sustainable snow contaminant remediation technology†

Seasonal snow covers up to 33% of the Earth's surface. Fresh falling snow serves as a snapshot of atmospheric processes and can take up pollutants. Once deposited, snow can affect the Earth's radiation and climate change, and its melting and accumulation processes can affect human health. Little has been done for snow pollution remediation, especially regarding emerging materials and nano/microplastics in urban regions. We present a sustainable, cost-effective snow remediation filtering system made of multilayer clay-based minerals, specifically kaolin and montmorillonite, capable of removing nano/micro-contaminants from snow. In addition, a recycled metallic mesh with various pore sizes, including nano/micro size, can remove substantial snow contaminants. Using a suite of technologies including high-resolution S/TEM, Pelletier ice nucleation counter, NALDI mass spectrometry, Photoacoustic Extinctiometer (PAX), triple quad ICP-MS/MS, and TOC counter, we found that the clay-mineral setup is highly efficient. For instance, it removes metallic species (>95%), plastic micro/nanoparticles like polyethylene glycol and polyethylene (>99%), black carbon (>93%), and total organic carbon (>50%) from dirty snow sampled in the primary snow depository in downtown Montreal. This sustainable and inexpensive method is promising for significantly reducing the environmental impact of snow pollutants, improving current snow remediation practices in urban areas, decreasing the re-emission of contaminants in air, soil, and water leaching, and improving the ecosystem and human health.