Variations in elemental and isotopic compositions of Cu, Zn, and Cd in mushrooms: are they site- or species-dependent?

A B S T R A C T We studied the elemental and isotope systematics of Cu, Zn, and Cd in Imleria badia mushroom and the related soil samples from six sites underlain by granite, amphibolite, and peridotite bedrock. The soils contain varying amounts of Cu, Zn, and Cd and exhibit a wide range of δ 65 Cu (-0.85 to +0.67‰), δ 66 Zn (-0.06 to +0.25‰), and δ 114 Cd (-0.73 to -0.37‰) values. Mushrooms show site-dependent concentrations only in the case of Cd. Isotopes of Cd, Cu, and Zn fractionate to different degrees during both uptake from the substrate and within-mushroom translocation. Mushrooms display higher uptake of isotopically heavier Zn (Δ 66 Zn FB-soil = 0.33 to 1.03‰) and Cd (Δ 114 Cd FB-soil = 0.17 to 0.47‰), and predominantly isotopically heavier Cu (Δ 65 Cu FB-soil = -0.08 to 1.47‰). The degrees of within-mushroom isotopic fractionation are insignificant: Δ 65 Cu had a total range of values of 0.38‰; Δ 66 Zn, of 0.53‰; and Δ 114 Cd, of 0.15‰ for the mushroom samples. Individual samples show the extent of within-mushroom isotopic fractionation (Δ x E) from -0.29 to 0.13‰ for different elements. The study suggests that some elemental and isotopic differences in the analyzed mushrooms are more species-dependent than site-dependent.