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Among the heavy metals (HMs) whose concentrations in natural environments have risen considerably in the last era, chromium (Cr) is one of the most toxic. Because of the risks it poses to human and environmental health, it is of great importance to screen the variation in Cr contamination in the atmosphere and decrease the pollution. This study aimed to determine the proper tree species that can be used to monitor and reduce Cr contamination. For this aim, studies were conducted on Tilia tomentosa, Robinia pseudoacacia, Cedrus atlantica, Pseudotsuga menziesii, and Fraxinus excelsior species growing in Düzce, which is among the 5 most contaminated European towns according to the World Air Pollution report. Samples taken from these trees were examined, and changes in Cr concentration depending on species, organs, compass direction, and age range in the last 60 years were evaluated. Results indicated higher Cr pollution in recent years, consistent with higher traffic density, but that there was no consistent effect of compass direction. It was also determined that the tree species most appropriate for screening the variation in Cr contamination in the airborne were Tilia tomentosa, and the most appropriate species for decreasing pollution were Robinia pseudoacacia and Cedrus atlantica.

Heavy metals (HMs) are natural components of the Earth's crust that might originate from natural and anthropogenic sources. In excess quantities, the presence of these metals is harmful for both environment and human health. Taking this into account, various investigators examined bioaccumulator species in order to reduce environmental toxicity, among these Baccharis trimera. Therefore, the present study aimed to determine the capacity of B. trimera to bioaccumulate HMs and assess consequent cytogenotoxicity following exposure. B. trimera vegetative parts were collected from two groups (1) control, in which plants were cultivated in soil exposed to distilled water, and (2) exposed, in which plants were cultivated in soil exposed to HMs including manganese (Mn), iron (Fe), lead (Pb), copper (Cu), cobalt (Co), zinc (Zn), and chromium (Cr). HMs were quantified in cultivation soil and extracts (aqueous and ethanolic) as well as infusion of B. trimera vegetative parts. Root lengths and cytogenotoxic effects were determined using Allium cepa test. Results demonstrated that all HMs studied were absorbed and bioaccumulated by B. trimera. Root lengths were decreased when exposed to ethanolic extract of B. trimera cultivated in soil exposed to HMs solution, which was the extract that exhibited the highest cytogenotoxicity values. Thus, data demonstrated that B. trimera might serve as a bioaccumulator for the reduction of environmental toxicity associated with the presence of certain HMs. [ABSTRACT FROM AUTHOR]