Does Winter Outdoor Recreational Traffic Impact Concentrations of Microplastics in Colorado's Snowpacks? International Snow Science Workshop 2026, Whistler, Canada

Microplastics have become a growing concern within our natural environments and are increasingly prevalent in remote areas.This research aims to investigate how outdoor recreational traffic influences microplastic concentrations in Colorado's snowpacks.Snow samples were analyzed from high-traffic, medium-traffic, and pristine areas.Samples were placed in glass jars with metal lids to avoid self-contamination.At some sites, multiple samples were collected, either from different parts of the snowpack or varying geographic features.Particles were separated into two size fractions using a stacked sieving method: ≥250 µm and ≥20 µm.The larger fraction was filtered and manually examined under a dissecting microscope and characterized by shape and color.The smaller fraction underwent digestion and density separation before being filtered onto PES filtration paper via vacuum filtration for visual analysis.Results indicate no statistically significant difference in microplastic concentrations across the three sample sites (Kruskal-Wallis test: p = 0.1621), suggesting that concentration may not solely relate to human traffic.These findings support the hypothesis that microplastics are transported through atmospheric deposition and less through direct human influence in alpine regions.This study addresses an urgent gap in environmental science, especially considering that Colorado's mountain snowpacks are a primary water source for the Western United States.