Widespread microplastic contamination in Australian soils: Sources, pathways, and environmental implications

Area of Science:

• Environmental Science
• Ecotoxicology
• Polymer Science

Background:

• Microplastics are pervasive environmental pollutants, transported via multiple pathways.
• They can adsorb external contaminants and contain internal additives, posing risks.
• Their environmental persistence, bioaccumulation, and toxicity are significant concerns.

Purpose of the Study:

• To quantify microplastic abundance and types in Australian soils.
• To investigate microplastic contamination across diverse land use settings.
• To identify dominant polymer types and particle morphologies.

Main Methods:

• Analysis of 55 soil samples from Victoria and New South Wales, Australia.
• Identification of 13 different polymers in the 10–1000 μm size range.
• Foam fractionation technique used for microplastic separation from soil matrix.

Main Results:

• Mean microplastic abundance of 14,400 ± 20,000 particles/kg (median: 4200).
• Particles predominantly ranged from 10–100 μm in size.
• Acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polyethylene (PE), and polyurethane (PU) were the most prevalent polymers.
• Fragments (38%) and pellets (27%) were the dominant morphologies.

Conclusions:

• This study provides the first comprehensive survey of microplastics in Australian soils.
• Microplastic contamination is significant across various land use types.
• Understanding polymer types and morphologies is crucial for risk assessment and mitigation strategies.