Mass, composition, and sources of particulate matter in residential and traffic sites of an urban environment

摘要

Present study aims to assess the mass, composition, and sources of PM_(10) and PM_(2.5) (particulate matter having aerodynamic diameter less than or equal to 10 and 2.5 μm aerodynamic diameter, respectively) in Vellore city. Seasonal samples collected in traffic and residential sites were analyzed for ions, elements, organic carbon (OC), and elemental carbon (EC). Source apportionment of PM_(10) and PM_(2.5) is carried out using Chemical Mass Balance, Unmix, Positive Matrix Factorization and Principal Component Analysis receptor models. Results showed that traffic site had higher annual concentration (PM_(2.5) = 62±32 and PM_(10)=112±23 μg m~(-3)) when compared to residential site (PM_(2.5) = 54±22 and PM_(10) = 98±20 μg m~(-3)). Al, Ca, Fe, K, and Mg known to have crustal origin dominated the element composition irrespective of PM size and sampling site. Among ions, SO_4~(2-) accounted highest in both sites with an average of 70 and 60 to PM_(2.5) and PM_(10) ionic mass. Elemental carbon contribution to PM mass was found highest in traffic site (PM_(2.5)=17 to 23 and PM_(10) = 8 to 10) than residential site (PM_(2.5) = 9 to 17 and PM_(10) = 4 to 8). Elements, ions, OC, and EC accounted 12, 28, 34, and 16 of PM_(2.5) mass and 12, 21, 20, and 8 of PM_(10) mass, respectively. Different sources identified by the receptor models are resuspended road dust, crustal material, secondary aerosol, traffic, non-exhaust vehicular emissions, secondary nitrate, construction, cooking, and biomass burning. Since Vellore is aspiring to be a smart city, this study can help the policymakers in effectively curbing PM.