Photon and thermal neutron activation analysis were used to analyze airborne particulate matter obtained during the period January to March of 1984 for up to thirty elements. Elemental concentrations and meteorological data from the Toronto, Ontario area were subjected to factor analysis and the major sources of particulate deduced. Elemental profiles for six sources, viz. crustal soil, automobile exhaust, road salt, refuse incineration, oil combustion and an unidentified arsenic source, were used in a chemical element balance to quantitatively determine the contribution of each source to the ambient aerosol. Re-entrained soil contributed 67%, automobile exhaust contributed 15% and the other sources contributed lesser amounts to the inorganic particulate matter. Particle-size distributions for nine elements, viz. Al, Fe, Sc, As, Br, Cl, Zn, Mn, V, are presented as an argument for the development of receptor models involving particle-size distribution data.
Photon and thermal neutron activation analysis were used to determine the concentrations of up to thirty elements in aerosol samples collected by cascade impactor in Toronto, Canada during the period July to December of 1985. Examination of the particle-size distributions thus obtained led to the development of a new receptor model. A size-specific elemental mass balance (SSEMB) was used to apportion the mean ambient Pb aerosol concentration amongst four contributing sources as follows: secondary lead refinery emissions (46%), refuse incineration (28%), automotive exhaust (25%) and re-entrained soil and dust (<1%). The predicted concentrations of Al, As, Br, Na, Pb, Sb, and Zn agreed with observed concentrations to within a factor of two for most elements in most particle size fractions.
The use of particle-size distribution measurements and techniques for aerosol physical characterization, together with composition data for 30 elements, has led to useful deductions about the sources of airborne particulates. Collections with cascade impactors operated at three locations in Toronto, Canada, were analyzed by INAA and photonuclear activation (IPAA). The efficiency and reliability of impactors for aerosol size-distribution characterization was studied by scanning electron microscopy and calculating equivalent aerodynamic diameters; values obtained in this way were in close agreement with predicted values. Toronto aerosols exhibited both expected and unusual particle-size distribution patterns with many elements exhibiting either size distributions biased toward large (e.g. Al, Sc, Ti, Fe) or small particles (e.g. Br, Cl, Cu). Other elements (viz. Pb, Zn, As, Sb) exhibited different and unusual size distributions, presumably from different sources. Factor analysis and chemical mass balance (CMB) applied to data for a suburban site allowed emission source identification and aeorosol apportionment with a fair degree of certainty, and, preliminary results using factor analysis for size-fractionated samples, indicate a potential for relatively accurate source apportionment in more complex airsheds.
Authors:T. Pringle, S. Landsberger, W. Davidson and R. Jervis
Instrumental photon and neutron activation techniques have been compared through the determination of sixteen major, minor and trace constituents in two British Columbian coals and a standard coal. Between the two techniques, the results generally agreed to within one standard deviation with replicate precision being maintained, for both techniques, below twenty percent at worst and down to five percent or better for several elements. Almost all of the elements having environmental, industrial or economic significance in fossil fuels can be determined with good sensitivity by either of these two methods, both of which share the advantages of being non-destructive and multi-element in nature and sufficiently accurate as demonstrated in this paper.