A highway of pollution with no boundaries: a study using lead isotope ratios in wet deposition and lichen to trace atmospheric pollution

Abstract

To fingerprint lead deposition over approximately a two year timeframe, possible variationsin the sources of lead pollution over Northern Ontario was investigated by collecting snowpack, rainwater and lichen. The collection of samples was along two main transects: A West East transect between Sault Ste. Marie and Sudbury; and a South North transect from Sudbury up through Timmins to Kapuskasing. Sample collection along these two transects was conducted during the summer of 2009 and during the Shutdown of Vale Inco’s Smelter in the winter month of January 2009. The objective was to determine if Pb anthropogenic pollution from major point sources in northern Ontario (Essar Steel Algoma, Xstrata Sudbury Smelter Operations, Xstrata Kidd Metallurgical Plant) could be traced using isotopic ratios. As a result the Pb isotope fingerprint in northern Ontario can be explained by a binary mixing of anthropogenic emissions from northern Ontario refining operations and coal fired power plant emissions that are transported with prevailing winds from the Ohio Valley. Major point sources showed distinct differences in signatures and samples that were not collected in proximity to a point source were diluted and greatly influenced by the U. S signature.