Microplastic pollution on hiking and running trails in Australian protected environments

Area of Science:

• Environmental Science
• Ecotoxicology
• Pollution Studies

Background:

• Microplastics (MPs) are pervasive environmental contaminants, found globally, including in remote natural settings.
• Recreational activities like hiking and trail running introduce MPs into protected areas with significant biodiversity.
• Limited data exists on the quantity and characteristics of MPs in soils within these sensitive environments, hindering risk assessment.

Purpose of the Study:

• To quantify and characterize microplastic (MP) pollution in two conservation areas in south-eastern Australia.
• To assess atmospheric deposition rates of MPs over a six-month period.
• To determine baseline MP levels on recreational trails and identify their sources.

Main Methods:

• Atmospheric deposition of MPs was measured over six months in conservation reserves.
• Baseline MP quantities were assessed on recreational trails within reserves and national parks.
• Physicochemical characteristics of detected MPs were analyzed.

Main Results:

• Atmospheric deposition averaged 17.4 MPs/m²/day, predominantly fibers (84%).
• Trail surfaces contained 162.5–168.7 MPs/linear meter, with diverse physical and chemical properties.
• Polyurethane, polyethylene terephthalate, and polystyrene were the dominant MP types; 47–71% were fibers, originating from clothing, footwear, litter, and diffuse sources.

Conclusions:

• Microplastic pollution is present in protected natural areas, with atmospheric deposition and recreational activities as significant contributors.
• Fibers constitute a major fraction of MPs found in both atmospheric deposition and on trail surfaces.
• Addressing MP pollution in these environments is challenging due to multiple sources and retention factors.