Monitoring the Atmospheric Deposition of Heavy Metals at Source and Non-Source Oriented Sites of Varanasi, India

摘要

We measured the atmospheric depositions of total particulates and seven heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) at twentytwo urban and sub-urban locations of Varanasi, a holy city of India. Heavy metals in bulk deposits were measured using atomic absorption spectrophotometry. Atmospheric depositions of Zn remained highest (31.65 to 636.15 g ha~(-1)y~(-1)) followed by Mn (8.1 to 379.5 g ha~(-1)y~(-1))), Pb (5.0 to 140 g ha~(-1)y~(-1))), Cu (4.5 to 122.7 g ha~(-1)y~(-1))), Ni (2.0 to 58.1 g ha~(-1)y~(-1))), Cr (5 to 55 g ha~(-1)y~(-1))) and Cd remained the lowest (0.45 to 17.7 g ha~(-1)y~(-1))). The deposition of heavy metals remained highest during winter and lowest during rainy season. Atmospheric emissions coupled with wind actions appeared to have raised atmospheric loadings of heavy metals even in areas far away from source oriented sites. Since the city of Varanasi is flanked by a vast stretch of holy river Ganga at one side and agricultural lands at other sides, our data have relevance establishing air-soil-water-vegetable continuum of heavy metals from a human health perspective.