INSTRUMENTAL NEUTRON-ACTIVATION ANALYSIS OF AMBIENT AIR DUST PARTICULATES FROM METROPOLITAN CITIES IN INDIA

Ambient air dust samples were collected from industrial, commercial an d residential areas of four metropolitan cities (Delhi, Calcutta, Madr as and Cochin) in India, and were analysed for 27 elements (As, Ba, Br , Ce, Co, Cr, Cs, Cu, Eu, Hf, Hg, Fe, Ga, La, Lu, Na, P, Sb, Sc, Se, S r, Ta, Tb, Th, Rb, Yb and Zn) by Instrumental Neutron Activation Analy sis (INAA). Samples were irradiated with thermal neutrons in a nuclear reactor for 1 day and counted by high resolution gamma spectrometry a t different intervals. Several environmental standards such as Coal (S RM 1932b); Urban Particulate Matter (SRM 1648) from NIST USA; Vehicle Exhaust from NIES, Japan; and Soil-5 from IAEA, Vienna were also analy sed for quality assurance. The results reveal that the concentrations of several pollutant elements in dust samples from the four cities are highly variable. Wide differences were observed for elemental concent rations of As, Ba, Br, Cu, Cr, Hg, Fe, Sb, Se and Zn and these variati ons are explained in terms of their possible sources of origin.