Variation of 40-year Pb deposition in some conifers grown in the air-polluted-urban area of Düzce, Türkiye

Abstract Lead (Pb), one of the most lethal heavy metals (priority contaminant) in environmental and human health, spreads to the air as a metal or compound and has noxious properties. Therefore, tracking and diminishing Pb pollution are urgent and priority research topics. This study aims to contribute to the determination of suitable biomonitor species that can be used to observe Pb pollution shifts over a long period and hyperaccumulator species that can be used to lessen pollution. For this reason, it was selected to use species from Düzce, one of the five most unclean municipalities in Europe, including Pinus pinaster , Pseudotsuga menziesii , Cupressus arizonica , Cedrus atlantica , and Picea orientalis . The Pb concentration variations based on the species, organ, direction, and age range in the last 4 decades were assessed by examining the samples taken from tree species. The highest Pb concentrations were found in the outer bark and the east and north directions (high vehicle density) in almost all the species. These results showed that Pb pollution increases significantly due to vehicles. In conclusion, the displacement of Pb in wood was limited in these species; therefore, they could be used to track the Pb pollution change. C. arizonica and P. menziesii were determined to be suitable for reducing Pb pollution.