Determination of ultratrace (

Abstract

There is on-going concern regarding fugitive emissions of trace elements from mining and upgrading of the Athabasca Bituminous Sands (ABS) in northern Alberta, Canada, but remarkably few quantitative elemental data about the resource itself exists. By exploring advances in analytical techniques, an inductively coupled plasma sector field mass spectrometry (ICP-SFMS) method was developed for the determination of trace and ultratrace amounts (<0.1mg/kg) of several elements of environmental concern (Ag, As, Be, Bi, Cd, Pb, Sb and Tl) in bulk ABS and respective bitumen and mineral fractions as separated materials. Samples (n=7) averaged 86±4% mineral matter and 12±3% bitumen. High pressure microwave digestion employing HNO3-HBF4 yielded good recoveries (100±20%) for Ag, As, Be, Bi, Cd, Mo, Ni, Pb, Re, Sb, Tl and V in certified reference materials (NIST 1635, NIST 2711). The distribution of elements within the ABS was dichotomous, with V, Ni, Mo and Re predominantly found in the organic fraction (bitumen) and Ag, As, Be, Bi, Cd, Pb, Sb, and Tl predominantly found in the mineral residue. Trace amounts of As and Pb (0.1–2.0mg/kg), plus ultratrace amounts of Ag, Bi, Cd, Sb and Tl (<0.1mg/kg) were found in the bitumen. Despite filtration (<0.45µm), the bitumen fraction also contained trace amounts of lithophile elements (Be, Co, Ga, Sc, Y, Sm, Dy, Th), which suggested that the occurrence of Ag, As, Be, Bi, Cd, Pb, Sb, and Tl in bitumen was associated with ultrafine clays. Our demonstration of a distinct separation of the ABS trace elements into organic (V, Ni, Mo, Re) and mineral fractions (effectively all other trace elements) may have profound consequences regarding emissions of trace elements to the environment from the industrial development of this resource in northern Alberta.