Microplastics in soils of wilderness areas: What is the significance of outdoor clothing and footwear?

Microplastic pollution in terrestrial environments is an emerging issue worldwide (Lassen et al., 2015, Qi et al., 2018, Zhang and Liu, 2018). Microplastics are a heterogeneous class of plastic particles that vary in size (1 μm to 5 mm), shape (e.g. thin linear microfibers, irregular-shaped fragments, spherical microbeads) and chemical composition, comprising a range of polymers and additives (Frias and Nash, 2019, Rochman et al., 2019). Research to date has focused on industrial and agricultural areas (Fuller and Gautam, 2016, Liu et al., 2018). While there is emerging evidence of long distance microplastic transport to remote areas (Allen et al., 2019, Evangeliou et al., 2020), there is very limited data on microplastic abundance, fate and impacts in natural, wilderness or ecologically protected areas (Scheurer and Bigalke, 2018). Abrasion of rubber and synthetic fibers from outdoor recreation footwear and clothing may be a leading source of microplastics in these areas, which have minimal direct pollution sources other than foot traffic.