Sphagnum mosses from 21 ombrotrophic bogs in the Athabasca Bituminous Sands region show no significant atmospheric contamination of “heavy metals”

Abstract

Sphagnum moss was collected from twenty-one ombrotrophic (rain-fed) peat bogs surrounding 39 open pit mines and upgrading facilities of Athabasca Bituminous Sands in Alberta (AB). 40 Compared with contemporary Sphagnum moss from four bogs in rural locations of southern 41 Germany (DE), the AB mosses yielded lower concentrations of Ag, Cd, Ni, Pb, Sb and Tl, 42 similar concentrations of Mo, but greater concentrations of Ba, Th and V. Except for V, 43 compared to the “cleanest”, ancient peat samples ever tested from the northern hemisphere (ca. 44 6,000 to 9,000 years old), the concentrations of each of these metals in the AB mosses are within 45 a factor of three of “natural, background” values. The concentrations of “heavy metals” in the 46 mosses, however, are proportional to the concentration of Th (a conservative, lithophile element) 47 and therefore are contributed to the plants primarily in the form of mineral dust particles. 48 Vanadium, the single most abundant trace metal in bitumen, is the only anomaly: in the AB 49 mosses V exceeds that of ancient peat by a factor of six; it is therefore enriched in the mosses, 50 relative to Th, by a factor of two. Compared with the surface layer of peat cores collected in 51 recent years from across Canada, from British Columbia to New Brunswick, the Pb 52 concentrations in the mosses from AB are far lower.JRC.E.5 - Nuclear chemistr