Contribution of dusts to trace element inventories in pioneering plants growing on a pilot-scale pit lake watershed

Dusts containing trace elements (TEs) are deposited onto and can easily be retained on the surfaces of plants and adjacent soil, especially in areas with intense open pit mining, aggregate extraction, and road traffic. In this study, a greenhouse experiment was designed to evaluate the uptake of selected TEs from soil by Foxtail Barley (FB) in the absence of dust. The plant seeds and the soils used in the pot experiment were collected at Lake Miwasin (LM), a pilot-scale pit lake, with the soil from a stockpile prepared before bitumen mining began. Plants were grown inside laminar flow, class 100, metal-free clean air cabinets (CACs), in this soil and in soil spiked with elements that are enriched in bitumen: V (15 and 75 mg/kg), Ni (5 and 25 mg/kg), and Mo (1 and 5 mg/kg). Hoagland's solution was used as a nutrient source for one set of treatments. Conservative lithophile elements in plant shoots were far more abundant in plants growing at LM compared to those grown inside the CACs, indicating significant contributions from dust at LM; this was confirmed using SEM analyses. The addition of V, Ni, and Mo to the soils significantly increased their concentrations in the plants (p < 0.05), but plant growth was not significantly impacted. In regard to the bioaccumulation of TEs by plants, the study highlights the importance of determining their primary sources, beginning with atmospheric dust, in order to accurately assess root uptake from soil, and translocation into the shoots.