Trace elements in berries collected near upgraders and open pit mines in the Athabasca Bituminous Sands Region (ABSR): Distinguishing atmospheric dust deposition from plant uptake.

There are ongoing concerns regarding environmental emissions of trace elements (TEs) from bitumen mining and upgrading in the Athabasca Bituminous Sands Region (ABSR). Depending on their physical and chemical forms, elevated concentrations of potentially toxic TEs in berries could pose a health risk to local indigenous communities because native fruits are an important part of their traditional diet. The objective of this study was to distinguish between aerial deposition of TEs versus plant uptake, in cranberries, lingonberries, and blueberries growing in the ABSR. The concentrations of TEs were determined using ICP-MS in the metal-free, ultraclean SWAMP lab at the University of Alberta. The spatial variation in abundance of conservative, lithophile elements such as Y in berries resembles the published map of dust deposition rates obtained using Sphagnum moss. The presence of dust particles on the surface of the berries near open pit mines and upgraders was confirmed using SEM. Elements which show strong, positive correlation with Y include Al, Cr, Pb, U, and V; these are supplied mainly by dust. Elements which are largely independent of Y concentrations include Ba, Cd, Cu, Mn, Mo, Ni, Rb, Sr, and Zn; these are obtained primarily by plant uptake from soil. The concentrations of elements associated with dust were considerably reduced after washing with water, but the elements independent of dust inputs were unaffected. Elements which are supplied almost exclusively by dust (e.g. Y) are more abundant in berries from the ABS region (2 to 24 times), compared to berries from remote locations.

A geochemical perspective on the natural abundance and predominant sources of trace elements in cranberries (Vaccinium oxycoccus) from remote bogs in the Boreal region of northern Alberta, Canada.

Trace elements in native cranberry (Vaccinium oxycoccus) were compared with the underlying Sphagnum moss on which it grows, from two remote ombrotrophic (rain-fed) peat bogs in northern Alberta, Canada. The purpose of the comparison was to distinguish between dust inputs to the berries versus plant uptake from the substrate, and to determine the natural abundance of trace elements in native berries. Using Al as an indicator of the abundance of soil-derived mineral particles, the abundance of dust on the surface of the berries is 20 to 29× lower than that of the substrate (moss). Other lithophile elements (V, Cr, Co, Ga, Li and Y) show similar differences between moss and berry. The concentrations of Rb and Ba in berries were similar to moss and Sr within a factor of 3 to 4×, probably reflecting passive uptake of these lithophile elements by the plants, even though they have no known physiological function. Of the micronutrients examined (Mn, Fe, Ni, Cu, Zn and Mo), Cu and Mn were more abundant in berries than moss, Ni and Zn yielded similar concentrations in both whereas Fe followed by Mo showed the greatest concentration difference. For these micronutrients, uptake by the plants through their roots via the substrate (moss and peat) outweighs contributions from atmospheric dusts. In respect to potentially toxic "heavy metals", Pb concentrations in the moss (BMW, 89 ±â€¯7.3 µg/kg; CMW, 93 ±â€¯27 µg/kg) are below the natural, "background" values reported for ancient layers of Swiss peat from the mid-Holocene (>6000 years old). The Pb concentrations in the berries, however, are 19 to 47× lower than in the underlying moss indicating that Pb in the berries, like Al, is exclusively supplied by dust. Cadmium in the berries is at or above the level found in moss due to active uptake by the plants from the substrate, most likely because of the chemical similarity of this element to Zn. Silver, Sb and Tl in the berries were