Imprints of vehicular pollution in roadside dust from Kolkata, India: insights from magnetic susceptibility, geo-statistical and SEM studies

The present study aimed to determine the magnetic susceptibility of roadside dust collected from different parts of Kolkata city, West Bengal, India. The average value of susceptibility was 4.96 × 10 –6 m 3 /kg, the highest being 19.6 × 10 –6 m 3 /kg and the lowest being 1.2 × 10 –6 m 3 /kg. The frequency-dependent susceptibility value (average = 2.19) indicated the dominance of stable-single domain grains with a low concentration of superparamagnetic grains at a few locations. SEM analysis showed morphological diversity of road dust – irregular, aggregate, angular and cloudy. Energy dispersive X-ray spectroscopy analysis of the dust particles revealed that Ca-rich, Na-rich and Fe-rich particles were abundant. Compositions were variable with the morphology. The mapping of magnetic susceptibility indicated that the susceptibility values were higher in areas with heavy vehicular traffic and other polluting sources. However, some areas with high pollution had open spaces, indicating the dispersion of magnetic pollutants. The study indicated the degradation of the environment due to anthropogenic activities.