Ambient air pollution in industrial areas is one of the significant problems increasing high emissions since the 1990s. Atmospheric trace metal deposition in the industrial estate has occurred, and some have shown toxic effects on humans and non-human biota. Tree bark and annual rings have been used as convenient biomonitors due to the highly absorbing capacity of several metals for passive samplers in recent decades. It gives information about the speciation of some pollutants and their transition between organs in the trees. Systematic differences in air pollution degrees can be recorded spatial or temporal by analyzing the annual rings of the trees. In this study, Cupressus arizonica, Platanus orientalis, and Robinia pseudoacacia have been selected as landscape trees to identify Al, Cr, and Mn pollution during the past 30 years in the urban environments of the İzmit, Türkiye. The widespread type of landscape species was compared to perform the deposition degree of several sites. Metal concentrations have been detected in the barks and wood due to the industrialization of the territory year-to-year. The study’s framework indicated that the applicability of Robinia pseudoacacia L. is the better choice for assessing the degree of atmospheric metal pollution, both historical and near-past, on local scales.

In previous studies, it was demonstrated that photocatalysis by TiO₂ nanoparticles can be effective for decomposition of pollen grains and pollen allergen extracts (PAEs) for Cupressus arizonica and Platanus hybrida species. In this work, the chemical and photochemical processes of five types of PAEs belonging to family Asteraceae, tribe Astereae, and family Poaceae, tribes Poeae and Triticea, were studied. It was confirmed that the PAEs suffered almost complete decomposition, which likely led to gaseous final products. For the species of Poeae tribe, i.e., Poa pratensis, Festuca pratensis, and Avena sativa, an unusual surface chemical modification of the photocatalyst consisting in the appearance of new bands on fine core level spectra of Ti 2p, C 1s, and O 1s was observed. These changes were associated with possible doping of TiO₂ with C and N by pollen extracts. This was accompanied by a red shift of absorption spectra. The results suggest that some components of Poeae pollen can be grafted on TiO₂ surface and they can activate the photocatalyst in the visible range. These findings can open a new pathway to eco-friendly chemical engineering of photocatalysts using organic biological compounds.