Tracing Anthropogenic Lead in Aerosols Using Isotopic Analysis of Spruce Needles, Bow Valley, Alberta, Canada

Abstract

Lead (Pb) is currently one of the most heavily studied inorganic pollutants due to its known and suspected adverse effects on human health and environment. In order to study anthropogenic Pb contamination via aerosol particulates, it is important to differentiate various sources of Pb. Fortunately, Pb ores generally have distinctly different isotopic signatures. So it is possible to trace anthropogenic lead to its source. Based on analyses of 2~176 from aerosol particulates, Sturges and Barrie (1989) showed that in eastern North America, one could differentiate U.S. versus Canadian Pb with their distinctly different 2~176 of c. 1.2 and 1.15 respectively. Blais (t996) supported these results by analysing the surface sediments from lakes in eastern Canada, and showed that U.S. and Canadian Pb have 2~176 of 1.213___0.008 and 1.153_+0.005 respectively. Thus using a simple isotope mixing model, one can estimate the contribution of Pb from each source. Carignan and Gari6py (1995) used epiphytic lichen, lake sediments, and spruce needles for 2~176 aerosol studies. Both organic material and the surface sediment of lake had very similar 2~176 indicating that all of them represent the contemporary Pb composition of aerosol contaminant. This study focuses on the development of a method in which one may use spruce needles as an indicator of contemporary aerosol Pb contamination.