Biomonitoring with bees and bee products: multielement profiles including technology-critical elements

Honeybees (Apis mellifera) and their products are valuable biomonitors of environmental pollution. This study reports the contents of 48 elements in samples of propolis, bees, pollen, honey, honeycomb, and wax from bee hives in Leoben, Austria. The samples were taken in three campaigns over a period of twelve months. After microwave-assisted acid digestion, the samples were measured with inductively coupled plasma tandem-mass spectrometry (ICP-MS/MS) using nitrous oxide (N2O) as reaction gas for analytes affected by spectral interferences. Matrix-specific patterns in multielement variations were explored with univariate and multivariate statistical analysis. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed four matrix clusters (propolis; bee; pollen; honey/honeycomb/wax), with element mass fractions generally decreasing in the order propolis > bee > pollen > wax ≈ honeycomb ≈ honey. Two analyte groups could be separated by their PCA loadings, one interpreted as predominantly particle-associated (Li, Al, V, Cr, Fe, Nb, Y, La, Ce, Sm, Eu, Gd, Tb, Dy, Ho, Ta, Sb, Bi, Pb) and the other as more soluble/bioavailable (Na, Mg, Ca, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Cd, Ba, Tl). Chondrite-normalized patterns of rare-earth elements including yttrium (REY) showed smooth profiles across all matrices, suggesting geogenic sources and negligible fractionation from biotransformation. Only minor differences were observed between different matrices from the same location. The observed contrasts in REY patterns in honey samples from Austria, Belgium, and Russia support their suitability for tracking regional environmental conditions.