Grant: Discovery Grants Program - Individual

All trace elements (TE) in the environment have a natural source, in addition to possible contributions from human activities. To quantify anthropogenic contributions, natural inputs must be known. We have used metals for thousands of years. Thus, to identify “background” rates of atmospheric deposition of TE, we need to go back in time, and this requires the judicious use of environmental archives such as peat bogs. Bogs are unique ecosystems because they receive inputs of TE exclusively from the air. While bogs are excellent environmental archives of atmospheric deposition, we have a limited understanding of how they function. We have used peat cores to reconstruct atmospheric lead deposition for the past 15,000 years, but still cannot explain why lead and other TE are so well preserved in the acidic, organic-rich, anoxic peat.The long-term objective of my program is to understand how peat bogs function as archives of atmospheric TE deposition, and to clearly distinguish between natural and human contributions of TE to the environment (air, soil, water, biota) at local, regional, and global scales.Over the next 5 years my research will focus on:1) the use of Sphagnum moss as biomonitors of contemporary atmospheric deposition;2) using peat cores from rain-fed bogs as archives of atmospheric deposition in the past; 3) determining the physical and chemical forms of TE in snow, surface and pore waters, and their significance for post-depositional migration;4) developing new chemical, chronostratigraphic markers for improving the reliability of our age-depth models; and 5) improving the existing model for the chemical composition of the natural, background “crustal aerosol” using our collection of ancient peat samples from five continents.Porewater chemistry is a valuable guide to the biogeochemical transformations taking place within the peat, but the low concentrations of TE require tremendous analytical sensitivity while minimizing the risk of sample contamination. Determining the concentrations of molecular species in porewaters is even more challenging, but key to understanding the ecological significance (bioaccessibility and bioavailability) of TE emissions to the environment. In our state-of-the-art, metal-free, ultraclean lab we will determine TE in natural waters as a function of particle size, measure stable lead isotopes for source assessment, and radioactive (210Pb) for age dating. The new discoveries to be made by HQP will present a more accurate perspective on atmospheric deposition of TE in Canada, providing policy-makers with an opportunity to directly compare the effects of industrial innovation and pollution abatement with environmental change. The HQP will develop the expertise to better understand the true impacts of resource development and other human activities around the world, ultimately leading to a cleaner and safer environment.