Temporal Variation of Atmospheric Aerosol Particulate Matters and Heavy Metal Concentrations in Dhaka, Bangladesh

Abstract

Aerosol particulate matters and heavy metal concentrations were measured for the period of August and September 2005 in Dhaka a Southeast Asian Mega City. Particulate matters (PM) of different size fractions (TSP, PM10 and PM2.5) were collected on the micro fiber filters by placing the PM sampler on the roof of the Mohkarram Hossain Khundhkar Biggan Bhaban at the Department of Chemistry, University of Dhaka, Bangladesh. The overall average concentrations of TSP, PM10 and PM2.5 were 68, 43 and 35 µg m-3, respectively. About 82% particles were from fine fraction (PM2.5) and 18% were from coarse fraction (PM10-2.5), which indicates mechanical processes are one of the main sources for the particulate matters in Dhaka. Heavy metals (lead, copper, zinc, and iron) concentrations were determined by using atomic absorption spectrophotometer (AAS) for the size fraction of PM10 with highest concentrations recorded for iron (2360 ng m-3) and lowest for copper (28 ng m-3). The average concentration for lead (96 ng m-3) was lower than the WHO guideline value and also lower than the previous measurements in Dhaka. The lower concentration of lead was found presumably due to the official ban of leaded gasoline in Dhaka, Bangladesh.

Keywords

• air pollution
• particulate matter
• TSP
• PM10
• PM2.5 and heavy metals