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

摘要

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-derivedmineral particles, the abundance of dust on the surface of the berries is 20 to 29x 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 tomoss and Sr within a factor of 3 to 4x, probably reflecting passive uptake of these lithophile elements by the plants, even though they have no known physiological function. Of themicronutrients examined (Mn, Fe, Ni, Cu, Zn andMo), Cu and Mnwere 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 "heavymetals", Pb concentrations in the moss (BMW, 89 +/- 7.3 mu g/kg; CMW, 93 +/- 27 mu g/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 47x lower than in the underlying moss indicating that Pb in the berries, like Al, is exclusively supplied by dust. Cadmiumin 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 bLOD, but assuming that they are supplied exclusively by dust inputs, their concentrations in the berries can be estimated from the Al concentrations. Taken together, these data provide an estimate of the natural abundance of these elements in berries, based on measured (Cd, Pb) and calculated (Ag, Sb, Tl) values. (C) 2018 Published by Elsevier B.V.