Nowadays, the applications of nanotechnology are increasing in various fields such as information technology, energy, the medical sector, and agriculture. Nanotechnology has proved its ability to solve problems in agriculture and related industries. Establishing the impact of nanoparticles on various ecosystems has become a primary research topic, but studies on forest ecosystems and trees are quite limited. This study examined the effects of silver nanoparticles on the germination parameters of oriental beech seeds and established their toxic threshold values. Silver nanoparticles were applied at concentrations of 200, 400, 600, 800, and 1000 mg/L to oriental beech (Fagus orientalis) seeds collected from 10 different populations in order to identify the germination rate, germination percentage, seedling height, root collar diameter, plumula length, radicle thickness, and radicle length parameters. The results revealed that silver nanoparticles have a negative effect on germination and seedling parameters of oriental beech seeds, and that this effect is clearly seen in the germination rate at 20 mg/L levels and in seedling characters starting from 60 mg/L dose, causing a decrease of 13% in germination rate, 24% in germination percentage, 40% in plumula length, and 30% in radicle length. The Kahramanmaras-Andirin population was found to be the most affected by nanoparticles, while the Bursa-Inegol and Ordu-Akkus populations were the least affected.

Heavy metal (HM) pollution in urban air, a global dilemma, has increased drastically in the last century. Aluminum (Al) is one of the HMs and a neurotoxic element that can be absorbed into human tissues through digestion, breathing, and skin. Al accumulation in humans can cause diseases and even cause death. Due to the risks it poses to human and environmental health, it is vital to track the Al contamination shifts in the airborne and decrease them. In this study, 40-year Al concentration differences in Pseudotsuga menziesii, Cedrus atlantica, Picea orientalis, Cupressus arizonica, and Pinus pinaster grown in Düzce, Türkiye, the fifth most polluted European town, in terms of direction, tree species, and tissue type were assessed. As a result, Al accumulation in the tissues generally varies as outer bark > inner bark > wood. Whole species can accumulate Al significantly, and Al transfer between adjacent cells in the wood part is limited. In conclusion, all species can be used as biomonitors to track temporal Al pollution changes. However, the highest concentrations, especially in the wood part, were observed in Cedrus atlantica, Picea orientalis, and Cupressus arizonica, and these species were chosen to be the most suitable species to be used in phytoremediation studies.

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.