Microplastic pollution from protective measures in urban construction should not be overlooked: A case study in Changzhou, China

Microplastics (MPs) pollution originating from urban construction activities has become an increasingly prominent environmental issue, yet it has long been overlooked. This study systematically investigated the abundance, characteristics, and degradation of MPs in dust-proof net-covered soil in Changzhou, a rapidly urbanising city in China. Results demonstrated that MPs abundance in covered soil (mean: 4140.7 items/kg) was 3.2 times higher than in adjacent uncovered soil (1304.7 items/kg), indicating dust-proof nets as a significant source of soil MPs. Raman spectroscopy analysis provided the overwhelming majority of MPs were polyethylene, directly verifying nets as the primary contaminant. Morphological analysis revealed distinctive contamination characteristics: fibres (50.5 %) and large particles (>1000 μm, 41.4 %) predominated, reflecting physical degradation of the netting. Quantitative assessment of polymer ageing via hydrocarbon and carbonyl indices identified a two-stage degradation mechanism: initial rapid chain scission followed by progressive surface oxidation. Based on remote sensing data estimates, the total coverage area of dust-proof nets in Changzhou reached 13.11 km² in 2024, accumulating approximately 2.57 × 10¹² MPs in the covered soil. Findings showed that construction protective measures themselves may constitute a significant pollution source. We proposed management strategies including source control, timely recycling, and enhanced regulation of dust-proof nets to mitigate this emerging environmental threat.