| Summary: | Specialization: Environmental Engineering Degree: Master of Science Abstract: The Athabasca River (AR) is the longest river in Alberta with a wide variety of natural and potential anthropogenic inputs. The purpose of this study was to quantify the spatial variation of trace element (TE) concentrations and forms in this aquatic system. Water samples were gathered along a 125-km stretch of the river and at three points across the river, in locations upstream, alongside and downstream from the industrial region. The samples were collected using the novel, metal-free sampling methods. With respect to water quality and the uptake/toxicity of trace elements, and to determine the biological significance of trace elements in the river, their size-based distribution amongst different colloidal forms (i.e. truly dissolved, primarily organic, and primarily inorganic) was measured in the dissolved fraction (i.e., 0.45 µm). Normalization to Th showed that no trace elements were enriched in the particulate fraction. In the dissolved fraction (< 0.45 µm), concentrations of As, Co, Cu, Ni, Pb, Re, and V were significantly (p < 0.05) more abundant downstream of industry. Within the dissolved fraction, Fe and Pb were found mainly as primarily inorganic colloids, while the other trace elements occurred predominantly in the mainly ionic/truly dissolved fraction (i.e., < ca. 1 kDa). The average concentrations of the investigated trace elements were far below the surface water quality guidelines in the Athabasca River. The PCA analysis indicated that tributaries contribute meaningful amounts of total and dissolved trace elements to the AR.
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