Heavy metal exposure and source profiling based on leaf-deposited particulate matter in Pune city.

This study investigates particulate matter deposited on plant leaves across 27 roadside, industrial, peri-urban, highway, and rural sites in Pune city to quantify metal concentrations, identify probable pollution sources, and evaluate inhalation-related non-carcinogenic health risk. Leaf-deposited dust offers a practical, low-cost approach for detecting metal-enriched urban microenvironments. Samples were analysed for ten elements, with concentrations following the order Ca > K > Fe > Na > Mg > Mn > Zn > Cu > Cr > Pb, reflecting dominant contributions from crustal material, construction activity, and resuspended road dust. Strong correlations amongst Ca, Fe, Mg, Mn, Pb, Cu, and Cr pointed to combined natural and anthropogenic influences. Enrichment factor analysis identified Cu, Zn, and Cr as substantially enriched at select traffic- and industry-influenced locations. Principal component analysis distinguished source groups linked to construction and road dust, vehicular emissions, biomass or food-related activity, and localised industrial inputs. Spatial analysis showed central urban sites were mainly influenced by construction, manufacturing, and vehicular dust, whilst outer-zone sites reflected additional industrial, agricultural, and resuspended dust contributions. Health risk assessment showed hazard quotients following the order Cr > Pb > Cu > Zn, with hazard indices for adults and children remaining below the non-carcinogenic risk threshold. However, localised enrichment of Cu, Zn, and Cr indicates that metal exposure potential is spatially uneven, even when overall risk estimates remain low. This highlights the need for zone-specific monitoring and source-targeted control of road dust, construction activity, traffic emissions, and industrial inputs in rapidly urbanising, mixed-use urban environments.