Proof of concept to characterize historical heavy-metal concentrations in atmosphere in North Turkey: determining the variations of Ni, Co, and Mn concentrations in 180-year-old Corylus colurna L. (Turkish hazelnut) annual rings

Heavy metals (HMs) are among the pollutants posing a significant threat to human, animal, and environmental health. Therefore, monitoring HM concentration changes, especially in the air, is crucial. This study used Corylus colurna L. (Turkish hazelnut) annual tree rings cut in 2020, and it was intended to define the 180-year variations in concentrations of Ni (nickel), Co (cobalt), and Mn (manganese) that are among the most harmful HMs. This study analyzed HMs concentrations in the wood, outer and inner bark in the north, south, east, and west directions and the seasonal variations in HM concentrations in tree rings. It was determined that, for all the three elements, the wood and barks significantly differed ( P