Atmospheric Trace Metal Exposure in a 60-Year-Old Wood: A Sustainable Methodological Approach to Measurement of Dry Deposition

Abstract

Urban trees are essential in improving environmental quality and enhancing human welfare in urban areas. They are being utilized increasingly as biomonitors of air and dust-borne heavy metals through dendrochemistry and comparative analytical methods. This study investigated the foremost concern essential nutrient metals, including aluminum (Al) and iron (Fe); also trace metals (cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), and lead (Pb)) in worldwide-distributed trees in units of mg kg−1 dry weight (d.w). For retrospective analysis, we hypothesized that its feasibility as a bioindicator of air pollution in Düzce, Türkiye, among the tree species should be assessed. Digested tree wood samples were processed via inductively coupled plasma optical emission spectrometry (ICP-OES) for all metals to test this hypothesis. Pearson's correlation analysis and principal component analysis were utilized to determine the origin of elements. The results showed that (i) the mean concentrations of the species were presented to be Fe (156 mg kg−1 d.w) > Al (100.56 mg kg−1 d.w) > Cr (15.82 mg kg−1 d.w) > Cu (12.43 mg kg−1 d.w) > Pb (6.76 mg kg−1 d.w) > Ni (5.98 mg kg−1 d.w) > Co (2.16 mg kg−1 d.w) > Cd (0.47 mg kg−1 d.w); ii) analysis of the bioconcentration factor (BCF) and metal accumulation index (MAI) showed that the maximum BCF and MAI value was stored in the Cupressus arizonica (2.30 for Pb) and Robinia pseudoacacia (70.65) in all species; iii) the tree woods were also capable of discriminating between affected areas, as sites near industrial and vehicular traffic indicated higher metal content. For this reason, it can be deduced that C. arizonica wood is a potentially suitable sink of atmospheric metal.