Earliest evidence for heavy metal pollution on wildlife in Middle Age Europe

Abstract

Effects of past anthropogenic metal pollution on the wildlife are understudied. We investigate trace element incorporation in the dentition of a 1000 BP-year-old brown bear from the Romanian Carpathians, an area known historically for strong metallurgical activities. Background values as well as unnatural high lead (Pb), lithium (Li) and zinc (Zn) levels in a circa 5‒6-year-old brown bear male were detected using trace element maps across its functional dentition. High-resolution elemental transects and histological sections reveal the seasonal extent of lead intake, which occurred during five recorded summers, i.e. when the animal was actively foraging. We interpret the elevated Pb, Li and Zn concentrations in the terminal growth lines as evidence for the earliest-known anthropogenic heavy metal pollution in a wild animal. Our study underlines the impact of early industrial activities in a large terrestrial omnivore, demonstrating that anthropogenic threats on wildlife were not solely driven by hunting or landscape modification during the most recent decades.