The Negligible Effect of Toxic Metal Accumulation in the Flowers of Melliferous Plants on the Mineral Composition of Monofloral Honeys

Abstract

The accumulation of heavy metals in plant pollen and nectar exposes pollinators to environmental contaminations. Although honeybees act as biofilters and impede the transfer of heavy metals to honey, possible antagonistic interactions could negatively affect the mineral composition of bee-processed nectar. The aim of this study was to assess the level of harmful metals (Cd, Pd, Hg, Al, Ni and Tl) in relation to essential macro- (K, Ca and Mg) and microelements (Mn, Fe, Zn, Cu and Se) in three melliferous plant species (n = 45)—rapeseed, dandelion, and goldenrod—using the ICP-OES method. Metal transferability to three types of monofloral honey (n = 45) produced from these plants was evaluated. Among the studied plants, goldenrod and dandelion were found to be Cd and Pb accumulators; however, regardless of the plant species, only traces of harmful metals were found in honey (<0.015 and <0.043 mg/kg, respectively). What is more, the adverse impact of accumulated toxic metals (Tl, Cd, Ni, Pb and Al) on Ca, Mg and K levels in plants was noted, though it was not reflected in honey. Our findings suggest that in moderately contaminated environments, toxic metals are not transferred to honey and do not disturb its beneficial mineral composition.