Heavy Metal Distribution in Road Dust Across Land-Use Types in Mizoram and Its Human Health Risk Assessment

Vollständiger Abstract

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Objectives: This study aimed to assess the levels and spatial distribution of heavy metals in road dust of various land-use areas of Aizawl and Lawngtlai, Mizoram and to assess the human health risk associated with the heavy metals. Method: Road dust samples were taken from agricultural, industrial, commercial, residential and solid waste disposal areas. Samples were digested using USEPA Method 3050B and analysed for Cr, Pb, Ni, Cu, Zn and Cd using atomic absorption spectroscopy. GIS was employed to investigate land-use and topographic factors, and the USEPA model was used to evaluate health risks to adults and children. Findings: The results showed that Zn was the predominant metal with mean concentration of 72.75 mg/kg in Aizawl and 60.60 mg/kg in Lawngtlai. The highest concentrations of Zn were 119.84 mg/kg and 80.30 mg/kg, respectively. Compared with Indian natural soil background values, Pb, Ni and Zn were enriched by 94.66%, 41.47% and 228.54% in Aizawl and 29.21%, 20.56% and 174.69% in Lawngtlai. There was no significant difference (p > 0.05) in metal concentrations between districts. Ingestion was the most important exposure pathway. The hazard indices were 0.070 and 0.218 for adults and children in Aizawl, respectively, and 0.035 and 0.176 in Lawngtlai, respectively, which are less than 1. Novelty: This study provides a baseline assessment of the integration of heavy metal concentration, land use, topography and human-health risk in two contrasting mountainous urban areas of Mizoram. Keywords: Heavy metals, road dust, land use, topography, human health risk assessment