Pollution characteristics and human health risk from trace metals in roadside soil and road dust around major urban parks in Delhi city

This study characterizes trace metal content in roadside soil and road dust in and around parks of Delhi. Parks in Delhi are generally built in proximity to major traffic roads due to lack of planning and land scarcity. The results indicate similar distribution pattern of trace metals in roadside soil and road dust, in the order Fe > Mn > Zn > Cu > Pb > Ni > Co. The finer fraction (< 63 μm) was found to have higher metal loading than the bulk fraction (< 2 mm). Lead exhibited high geo-accumulation index (Igeo) for both, road dust (3.2) and roadside soil (3.6). The overall pollution load index (PLI) of the zone for both, road dust (PLI = 0.9) and RS (PLI = 1.0), suggests that further contamination will deteriorate the site. Source apportionment by principal component analysis (PCA) identified industrial and traffic sources. Health risk assessment was carried out to assess carcinogenic and non-carcinogenic risk due to trace metal exposure. Hazard index (HI) indicates that all the studied metals are in safe limits, but Mn (HI > 1; for road dust) can pose non-carcinogenic risk to exposed children. Carcinogenic risk from particularly Ni exposure was found to be high for all the possible pathways, i.e. ingestion, inhalation and dermal. Risk calculated for exposed population revealed that children are more susceptible to non-cancer risk than the adults. The observed health risk by Ni indicates high carcinogenic risk for the urban population.