PubMed · 2026-05-19
Researchers burned loess soil mixed with varying amounts of polyethylene microplastics at temperatures up to 600°C to simulate wildfires and heatwaves. They found that melting microplastics clog soil pores at moderate heat, but as temperatures rise further and plastics burn off, pores reopen and even expand, permanently altering the soil's structure.
At 200-300°C, melted polyethylene microplastics reduced total soil porosity by 26.5%-63.6% relative to 100°C, with higher plastic content causing greater pore loss.
At 600°C, after plastics burned out, porosity rebounded to maximum values (0.031-0.043 mm), increasing 24%-258% compared to 300°C levels.
Mesopores (2-50 nm) dominated pore-size distribution across all conditions, but macropore proportion surged to 51.7%-55.2% at high temperatures in high-microplastic samples.