Propensity and repercussion of microplastics in the soil-water-urban continuum

Despite consistently increasing efforts to reduce legacy and emerging pollutants like microplastic (MP), agro-ecosystems, particularly soil carbon is alarmingly threated to be replaced by plastic carbon, endangering the one health. While MPs have witnessed unprecedented research focus and frequency spike, the hydro-biological aspects in connection to urbanization, agricultural practices and ecosystem services are not explicitly discussed. Hence, we provide a comprehensive examination of MP sources, transport, and factors influencing their migration in soil and groundwater, with specific emphasis on urbanization, surface-groundwater interactions, and flooding, its interactions with organic and inorganic pollutants, antibiotic resistance genes, and potential routes exposure to humans, and toxicity augmentation. The investigation explicitly establishes the fact that flood-prone countries exhibit higher MPs infiltration into the greater depth of soil profile. However, plastic mobilization during undefended flood events varies significantly across the globe. Notably, China stands out with the highest MP concentrations in both agricultural soil and groundwater samples compared to other countries. MPs are found to be heterogeneously distributed across different soil depths, from shallow (0-5 cm) layers to deeper ones (up to 40 cm). On the other hand rapid urban development increases plastic waste on streets and other urban areas, and thus the influence of hydro(bio)logy-urbanization-agro-ecosystems nexus become highly significant. As MPs migrate through vadose zone via both vertical and horizontal transport mechanisms, it is imperative that interdisciplinary collaboration of experts from environmental science, hydrogeology, microbiology, material science, and engineering to understand and mitigate MPs contamination to achieve sustainable development goals.