2:00 pm - 3:00 pm
A graduate seminar is a presentation of the student’s final research project for their degree.
This is a RENR MSc final exam seminar for Na Chen. This seminar is open to the general public to attend.
150 South Academic Building (SAB), University of Alberta, Edmonton AB
Thesis Topic: Trace elements associated with the coarse and fine aerosol fractions in Sphagnum moss within the Athabasca Bituminous Sands region
Abstract: The Athabasca Bituminous Sands industry in Alberta has dramatic impacts on the economy of the province. Nevertheless, with increasing industrial operations, environmental concerns are also raised regarding the contamination of air and water with trace elements (TEs). To better assess the influence of the industry to the surrounding ecosystems, it is crucial to determine the TEs associated with the coarse and fine aerosols which differ in their size and chemical composition. Here, Sphagnum mosses were used as biomonitors of atmospheric deposition, and contributions from bulk deposition and fine aerosols were estimated by determining the abundance of TEs in bulk moss and acid soluble ash (ASA). The ash content of moss clearly increased with decreasing distance towards industry, reflecting increasing mineral dust input. Total concentrations of conservative, lithophile elements such as Al, Y, and Th increased towards industry, along with metals enriched in bitumen (V, Ni, and Mo) and elements of concern (Pb, Sb, and Tl). Acid soluble concentrations of these elements (except for Mo) also showed obvious or slight increasing trends and correlated strongly or moderately with acid soluble Y. Exhibiting high acid soluble proportions, Al, Y, V, and Ni might be largely contributed by the ultrafine clay minerals such as kaolinite and illite. In contrast, Th, Mo, Pb, Sb, and Tl showed low acid soluble proportions, which could be more influenced by the deposition of larger minerals such as feldspars and heavy minerals (e.g., monazite, zircon) from bituminous sands. Silver and Cd, behaving more like micronutrients such as Cu and Zn, were more impacted by plant uptake than mineral dust deposition. The above results were supported by the calculated enrichments of TEs, particle size distribution, XRD, and principal component analysis. The study highlights the importance and necessity to determine the chemical reactivity of TEs in atmospheric dusts when evaluating their associated health risks to living organisms.