Dust load and heavy metals deposition in a seasonally dry tropical urban environment in varanasi

Due to rapid industrialization and urbanization lead atmospheric deposition of heavy metals and dust load to become a global problem. We investigated the deposition of dust and heavy metals (Pb, Cd, Ni, Zn, Mn and Cu) at selected urban and sub-urban sites of Varanasi, India. Dustfall samples from different sampling location were collected and selected heavy metals viz. Pb, Cd, Cr, Ni, Zn, Mn and Cu in them were determined by atomic absorption spectrophotometer. Average flux of 2.882, 0.338, 2.964, 12.220, 22.275 and 2.890 g h-1 y-1 were measured for Pb, Cd, Cr, Ni, Zn, Mn and Cu respectively. The result has shown that dust load significantly higher in summer and winter as compared to rainy season. The deposition rate of Ni, Pb, Mn and Cr were significantly higher during summer and that of Cd, Cu and Zn deposition rates were highest during winter. The present study showed that dust load and deposition rate of mostly heavy metals significantly higher during summer and lowest during rainy season and clearly points out the urban areas of the city have potential to elevate the levels of heavy metals in the atmospheric deposits.