Investigation of Sources of Atmospheric Aerosol at a Hot Spot Area in Dhaka, Bangladesh

Abstract

Samples of fine and coarse fractions of airborne particulate matter were collected at the Farm Gate area in Dhaka from July 2001 to March 2002. Dhaka is a hot spot area with very high pollutant concentrations because of the proximity of major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0-to 2.2-m and 2.2-to 10-m sizes. The samples were analyzed for elemental concentrations by particle-induced X-ray excitation (PIXE) and for black carbon by reflectivity methods, respectively. The data were analyzed by positive matrix factorization (PMF) to identify the possible sources of atmospheric aerosols in this area. Six sources were found for both the coarse and fine PM fractions. The data sets were also analyzed by an expanded model to explore additional sources. Seven and six factors were obtained for coarse and fine PM fractions, respectively, in these analyses. The identified sources are motor vehicle, soil dust, emissions from construction activities, sea salt, biomass burning/brick kiln, resuspended/fugitive Pb, and two-stroke engines. From the expanded modeling, ϳ50% of the total PM 2.2 mass can be attributed to motor vehicles, including two-stroke engine vehicle in this hot spot in Dhaka, whereas the PMF modeling indicates that 45% of the total PM 2.2 mass is from motor vehicles. The PMF2 and expanded models could resolve ϳ4% and 3% of the total PM 2.2 mass as resuspended/fugitive Pb, respectively. Although, Pb has been eliminated from gasoline in Bangladesh since July 1999, there still may be substantial amounts of accumulated lead in the dust near roadways as well as fugitive Pb emissions from battery reclaimation and other industries. Soil dust is the largest component of the coarse particle fraction (PM 2.2-10 ) accounting for ϳ71% of the total PM 2.2-10 mass in the expanded model, whereas from the PMF modeling, the dust (undifferentiated) contribution is ϳ49%.

Source Identification of Carbonaceous Aerosols During Winter Months in the Dhaka City

“…Gate is a also hot spot site due to the proximity of several major roadways intersection and large numbers of vehicles plying through the area (Begum et al 2005). The site is in the mixed area (i.e., commercial and semi-industrial area).…”

Impact of Banning of Two-Stroke Engines on Airborne Particulate Matter Concentrations in Dhaka, Bangladesh

“…Data from this site has been previously examined for source apportionment. 2 Motor vehicles were estimated to contribute ϳ50% of the PM 2.2 at this location. The purpose of the present study was to assess the effect of the removal of two-stroke baby taxies on air pollution based on PM and black carbon (BC) data obtained from this site.…”

“…The other sources of PM emissions are brick kiln around Dhaka, which mainly operate during the winter period, resuspension from all of the dusty unpaved roads, and refuse burning by slum dwellers. From source apportionment studies, 2 it was found that ϳ50% of PM Ͻ2.2 m (PM 2.2 ) comes from vehicular emissions. Thus, vehicles are believed to constitute the dominant source of air pollution in Dhaka.…”

“…Thus, vehicles are believed to constitute the dominant source of air pollution in Dhaka. 2,3 There are no power stations, significant industrial sources of emissions, or nearby desert that may produce particulate pollution. Therefore, much of the governmental actions to date have focused on vehicular emission control.…”

Identification of haze-creating sources from fine particulate matter in Dhaka aerosol using carbon fractions

“…There have been studies of the particulate matter concentrations and compositions for over a decade (Salam et al, 2003: Biswas et al, 2003Begum et al, 2004Begum et al, , 2005Begum et al, , 2010Begum et al, , 2013 (Begum et al, 2013). Many of these studies have included receptor modeling to identify the major source types contributing to the observed PM.…”