Seasonal Variation, Chemical Composition, and PMF-Derived Sources Identification of Traffic-Related PM₁, PM_2.5, and PM_2.5–10 in the Air Quality Management Region of Žilina, Slovakia

Particulate matter (PM) air pollution in the urban environment is mainly related to the presence of potential sources throughout the year. Road transport is one of the most important sources of PM in the urban environment, because it directly affects pedestrians. PM measurements were performed in the city of Žilina, Slovakia, at various road-traffic-related measurement stations over the course of several years. This paper evaluates changes in the concentration of the fine fraction (PM2.5), the ultrafine fraction (PM1), and the coarse fraction (PM2.5–10) over time. PM concentrations were measured by reference gravimetric method. Significant changes in PM concentrations over time due to the diversification of pollution sources and other, secondary factors can be observed from the analysis of the measured data. PM samples were subjected to chemical analysis inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of elements (Mg, Al, Ca, Cr, Cu, Fe, Cd, Sb, Ba, Pb, Ni, and Zn). The seasonal variation of elements was evaluated, and the sources of PM2.5, PM1, and PM2.5–10 were estimated using principal component analysis (PCA) and positive matrix factorization (PMF). PM2.5 (maximum concentration of 148.95 µg/m3 over 24 h) and PM1 (maximum concentration of 110.51 µg/m3 over 24 h) showed the highest concentrations during the heating season, together with the elements Cd, Pb, and Zn, which showed a significant presence in these fractions. On the other hand, PM2.5–10 (maximum concentration of 38.17 µg/m3 over 24 h) was significantly related to the elements Cu, Sb, Ba, Ca, Cr, Fe, Mg, and Al. High correlation coefficients (r ≥ 0.8) were found for the elements Mg, Ca, Fe, Al, Cd, Pb, and Zn in the PM1 fraction, Cd, Pb, and Zn in PM2.5, and Ba, Sb, Fe, Cu, Cr, Mg, Al, and Ca in PM2.5–10. Using PMF analysis, three major sources of PM (abrasion from tires and brakes, road dust resuspension/winter salting, and combustion processes) were identified for the PM2.5 and PM1 fractions, as well as for the coarse PM2.5–10 fraction. This study reveals the importance of non-exhaust PM emissions in the urban environment

Tissue-specific activity of the blind mole rat and the two nucleotide-mutated mouse αB-crystallin promoter in transgenic mice

The αB-crystallin and HspB2 genes are located ≈0.9 kb apart in a head-to-head arrangement in mammals. Previous experiments have shown that a truncated −668/+45 αB-crystallin enhancer/promoter fragment from blind mole rats (Spalax ehrenbergi), which have nonfunctional lenses, lacks lens activity and has enhanced muscle activity in transgenic mice. Here we show that the full-length mole rat αB-crystallin intergenic region behaves similarly in transgenic mice. A two-nucleotide mutation ((−273)CA→G) in the mouse αB-crystallin enhancer/promoter fragment mimicking the wild-type mole rat sequence functionally converted the mouse promoter fragment to that of the wild-type mole rat promoter when tested in transgenic mice. The reciprocal mutation in the mole rat promoter fragment ((−272)G→CA) did not affect its activity. Oligonucleotides from the wild-type mouse and mole rat αB-crystallin promoter region under study formed distinct complexes with nuclear proteins from cultured cells. The mouse mutant sequence lost binding ability, whereas the mutated mole rat sequence gained the ability to form a complex similar in size to that of the wild-type mouse oligonucleotide. Our data support the idea that blind mole rats' αB-crystallin promoter activity was modified during the evolution of subterranean life and shows that tissue-specific promoter activity can be modulated by changing as few as two apparently neutral nucleotides in the mouse αB-crystallin enhancer region, implying the importance of the context of regulatory sequences for promoter activity