Modelling land use influence on polymer-specific microplastics abundance and transportation from terrestrial to aquatic environments

Plastic waste has reached a major environmental crisis level. Human exposure to microplastics (MPs)- particles <5 mm - is linked to toxicity, oxidative stress, inflammatory responses, neoplastic change, and numerous chronic health effects. Effective mitigation requires a thorough understanding of factors that govern MP accumulation and transport. While quantitative analyses at the polymer level remain limited, the role of land use patterns in shaping polymer abundance and movement is especially underexplored. This study addresses this knowledge gap by characterising and quantifying polymer-specific MP abundance (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC)) in freshwater across four urban land uses (industrial, commercial, residential, and natural). Bayesian Network models were developed for two urban catchments, and a pooled model generated generalised estimates across both basins. PET and PP dominate industrial areas, while commercial areas show high PE, PVC, and PS levels. Residential areas contain elevated levels of all five polymers, and the natural regions are characterised by PE, PVC, and PS. These distinct polymer signatures reflect local activities associated with each land use. Regression outputs from the pooled model enabled quantification of individual polymer loads and prediction of concentrations at unsampled sites based on known land use profiles. Strong relationships were found between abundance and commercial/industrial land uses than with residential and natural settings. Consequently, mitigation strategies targeting industrial and commercial sectors will yield the greatest reductions in MP emissions. Study outcomes support targeted source control and efficient monitoring designs, and robust policy development for curbing microplastic pollution.