Comparative study on time weighted average, chemical characterization & source profiling of PM10 aerosols

Abstract

In most of the countries in the world, ambient air quality has improved considerably from the last few decades. This has been achieved by range of measures that are adopted till yet. However, there is convincing evidence, that current levels of air pollution still pose a considerable risk to the environment and to human health and is considered as one of six harmful pollutants as carcinogenic by USEPA. Basically particulate matter is a widespread air pollutant, consisting of a mixture of solid and liquid particles suspended in the air. Its size and composition is an important factor in determining its sources & effects. Larger particles (dia >2.5µm) which contain iron, silica, potassium, sodium, magnesium and chloride are likely from windblown soil, unpaved roads etc and smaller particles (dia<2.5µm) that contain elemental and organic carbon are likely from combustion sources. The present research work is based on time weighted average, chemical characterization and source profiling of PM 10 aerosols in the Industrial area of Mohali and Residential area of Chandigarh during period February 2018 to April 2018. The samples were collected on Whatmann’s filter paper using respirable dust sampler in three shifts of 8 hour each. The results shows that sampling of 8 hour for three shifts and taking 16 hour data of any two shifts may be comparable with 24 hour monitoring, leads to resource and time minimization. But this study is conducted on only two locations and may not be applicable to other ones. The mean concentration of PM 10 is 143µg/m3 at residential area with maximum average concentration is 187µg/m 3 and minimum average concentration is 102µg/m3 and 163µg/m3 at industrial area, with maximum average concentration is 193µg/m3 and minimum average concentration is 139µg/m3, which is found to be very high as per NAAQS. The chemical characterization of particulate matter includes trace metals (As, Pb, Ni, Cd, Cr, Mn, Zn, Br, Cu etc), Crustal species (Al, Mg, Ca, Fe, Si, Sc) and inorganic ions such as NH4+ , SO42-, NO3-, K+, F-, Cl-. The source apportionment study has been carried out using principal component analysis (PCA). The major sources identified crust material (31%), coal/ biomass burning (21%), industrial dust (18%), vehicular emissions (15%) and secondary emissions (7%).