Trace element composition of PM2.5 and PM10 from Kolkata – a heavily polluted Indian metropolis

Elemental composition of PM2.5 and PM10 was measured from 16 locations in Greater Kolkata in Eastern India. Sampling was carried out in the winter months of 2013–2014. PM2.5 and PM10 mass concentrations ranged from 83–783 μg/m3 and 167–928 μg/m3 respectively. 20 elements were measured with an Agilent 7700 series ICP–MS equipped with a 3rd generation He reaction/collision cell following closed vessel microwave digestion. In both size fractions Fe, Na, Al, K, Ca were present in high concentrations (>1 000 ng/m3), Mn, Zn and Pb demonstrated medium concentrations (>100 ng/m3), and Sc, V, Co, Ni, Mo, Cd, Sn and Sb had low concentrations (<100 ng/m3). Ca, Al, Mg, Sc, Ti, Mn and Fe were concentrated in the PM10 fraction, while the toxic metals (Cr, Ni, Zn, Mo, Sn, Sb, V, Co, Cu, Cd and Pb) were concentrated in the PM2.5 fraction. Al normalized Enrichment Factors (EF) showed EF<10 for Ti, Mg, Sc, Fe, Mn, Na, K, Ca, V, Co which is indicative of crustal sources, 100>EF>10 for Ni, Cr, Cu is possibly industrial influence and 1 000>EF>100 for Sn, Zn, Mo, Sb, Pb, Cd is related to industrial, high temperature combustion and vehicle sources. Factor analysis identified three possible sources for PM10; (1) abraded vehicular part related road dust, exhaust gases of car and municipal waste incineration (2) industrial emissions, and (3) coal combustion and non–ferrous metal smelting and three possible sources for PM2.5; (1) abraded vehicular part related road dust and industrial emissions (2) exhaust gases of cars and municipal waste incineration, and (3) coal combustion and non–ferrous metal smelting. In a risk evaluation using a U.S. EPA IRIS, chromium was found to have the highest excess cancer risk.