Size-resolved analyses of trace elements in snow from an open-pit bitumen mining and upgrading region

Area of Science:

• Environmental Science
• Geochemistry
• Environmental Chemistry

Background:

• Industrial activities like mining and smelting generate dust containing potentially toxic trace elements (TEs).
• The ecological impact of TEs depends on their concentration and chemical form, not just presence.
• Understanding TE distribution in environmental matrices is crucial for ecological risk assessment.

Purpose of the Study:

• To analyze the size-resolved concentrations and chemical forms of selected TEs in dusty snow from the Athabasca River.
• To assess the potential ecological risk posed by TEs in snowmelt to the aquatic environment.

Main Methods:

• Collected size-resolved dusty snow samples along the Athabasca River.
• Analyzed concentrations of conservative, lithophile, bitumen-enriched, and chalcophile elements.
• Characterized TE distribution in particulate, filterable, and truly dissolved fractions, including association with organic colloids.

Main Results:

• TEs were predominantly in the particulate fraction (>0.45 μm), increasing with proximity to industry.
• Elevated Al, Mo, and V were found in the filterable fraction (<0.45 μm) near industrial sites.
• Dissolved TE concentrations were very low, comparable to ancient ice, with some Ni and Y associated with organic colloids.

Conclusions:

• The mineralogical composition of particulate dust resembles local natural and anthropogenic sources.
• Despite industrial proximity, dissolved TE concentrations in snowmelt are generally below river averages, posing a limited threat to aquatic life.
• The physical and chemical forms of TEs in snow are critical factors in determining their environmental risk.