Area-wide distribution of lead, copper, and cadmium in air particulates from Chicago and northwest Indiana

Abstract

Published air pollution emissions inventories for the urbanized and industrialized area along the southwestern shore of Lake Michigan include few chemical analyses of particulates, and estimates of the elemental composition of airborne solids may be made only indirectly and compared with NASN analyses from a few locations. As a first attempt to examine the area-wide distribution of specific chemical elements in this region, lead, copper, cadmium, and bismuth were determined in 24-h average samples collected on glass fiber filters at 50 stations throughout the region. Samples from most of the 50 stations were obtained from local air pollution control organizations for 6 different days from May to August 1968 and were analyzed electrochemically by highly sensitive anodic stripping voltammetry (ASV). Throughout the area the small variation of lead, generally a few micrograms per cubic meter of air, did not exceed that expected from the distribution of automobiles, the major source. Cadmium was generally 200 times lower without marked local variations and was close to the expected concentration if coal combustion is the major source. Copper was generally 20 times lower than lead throughout Chicago as expected if coal combustion is the major source of copper. However, certain stations in the northwest Indiana area showed reproducible anomalies where copper was 100 times greater than in Chicago and several times greater than lead at the same stations. The source of this anomalous copper has not been determined.