SOURCES OF ATMOSPHERIC PARTICULATE HEAVY METALS IN URBAN DETROIT DURING THE SUMMER OF 1996

Amy E. Gildemeister*, Gerald J. Keeler (The University of Michigan Air Quality Laboratory, Department of Environmental and Industrial Health, School of Public Health, 109 South Observatory, SPH I, Ann Arbor, MI 48109-2029); Joseph R. Graney (Department of Geological and Environmental Studies, SUNY-Binghamton, NY, 13901)

Heavily industrialized urban areas often have numerous sources of atmospheric particulate trace metals. In Detroit, MI there exist diverse sources including coal fired power plants, waste incinerators, and metals foundries. With some prior knowledge of the typical metal source profiles and the potential sources located in the region, it is possible to use factor analysis to determine which source categories are contributing significantly to the overall variability in atmospheric particulate trace metals. Twenty-four hour total particulate trace metal samples were collected daily from April through October of 1996 at three sites with varying proximity to industry as a part of the City of Detroit Water and Sewerage Department Deposition Study of PCB's, Mercury, and Cadmium.

Five trace elements that are associated with anthropogenic atmospheric emissions are Hg, Pb, Cu, Ni, and Zn. Large spatial gradients in trace metal concentration exist within the city of Detroit with the mean concentrations of these metals varying with the proximity of the sampling site to industry. Mean mercury concentrations ranged from 29.5-53.5 pg/m3, lead from 15.9-29.2 ng/m3, copper from 7.0-51.5 ng/m3, nickel from 1.7 to 11.4 ng/m3, and zinc from 52.8-112.6 ng/m3. In the case of all of the metals except for copper, the highest mean concentrations were measured at the Livernois site which is located in a heavily industrialized part of Detroit. Copper concentrations in Detroit were highest at the St. Maron's Church site, which is located in an area with primarily light industry. A brass foundry located approximately .5 miles south of the St. Maron's site reports significant atmospheric copper emissions. Additional Detroit particulate metals sources identified using multi-variate factor analysis include the iron and steel industry, resuspended contaminated urban soil, oil, and two separate incineration signatures.