Pollen of Betula pendula, Ostrya carpinifolia and Carpinus betulus was exposed in vitro to two levels of NO2 (about 0.034 and 0.067 ppm) – both below current atmospheric hour-limit value acceptable for human health protection in Europe (0.11 ppm for NO2). Experiments were performed under artificial solar light with temperature and relative humidity continuously monitored. The viability, germination and total soluble proteins of all the pollen samples exposed to NO2 decreased significantly when compared with the non-exposed. The polypeptide profiles of all the pollen samples showed bands between 15 and 70 kDa and the exposure to NO2 did not produce any detectable changes in these profiles. However, the immunodetection assays indicated higher IgE recognition by patient sera sensitized to the pollen extracts from all exposed samples in comparison to the non-exposed samples. The common reactive bands to the three pollen samples correspond to 58 and 17 kDa proteins.

In urban areas, the demand for local assessment of air quality is high. The existing monitoring stations cannot fulfill the needs. This study assesses the potential of hyperspectral tree leaf reflectance for monitoring traffic related air pollution. Hereto, 29 Carpinus betulus saplings were exposed to an environment with either high or low traffic intensity. The local air quality was estimated by leaf saturation isothermal remanent magnetization (SIRM). The VIS-NIR leaf reflectance spectrum (350–2500 nm) was measured using a handheld AgriSpec spectroradiometer (ASD Inc.). Secondary, leaf chlorophyll content index (CCI), specific leaf area (SLA) and water content (WC) were determined. To gain insight in the link between leaf reflectance and air quality, the correlation between SIRM and several spectral features was determined. The spectral features that were tested are plain reflectance values, derivative of reflectance, two-band indices using the NDVI formula and PCA components. Spectral reflectance for wavelength bands in the red and short wave IR around the red edge, were correlated to SIRM with Pearson correlations of up to R = −0.85 (R² = 0.72). Based on the spectral features and combinations thereof, binomial logistic regression models were trained to classify trees into high or low traffic pollution exposure, with classification accuracies up to 90%. It can be concluded that hyperspectral reflectance of C. betulus leaves can be used to detect different levels of air pollution within an urban environment.

The objective of this paper is to give an account of the evaluation of the effect of urban habitat quality on dorsi-ventral leaf reflectance asymmetry to bio-monitor urban habitat pollution. Reflectance in the RGB bands of a reflex camera is measured at the adaxial and abaxial sides of Carpinus betulus L. leaves for two contrasting urban habitats, e.g.; suburban green and industrial habitats in the city of Gent (Belgium). Abaxial leaf reflectance is consistently higher than adaxial leaf reflectance. We quantified leaf dorsi-ventral reflectance asymmetry with a newly defined Normalized Dorsi-ventral Asymmetry Index (NDAI). The NDAI is significantly higher in industrial habitats as opposed to suburban green ones. Our optical observations indicate that changes in Carpinus betulus L. leaf morphology are related to urban habitat quality. Hence, we suggest that leaf dorsi-ventral reflectance asymmetry allows the estimation of the magnitude and spatial extent of environmental pollution in urban environments.

A long-term hydrological and water chemistry research was conducted in three experimental microbasins differing in land cover: (1) a purely agricultural fertilized microbasin, (2) a forested microbasin dominated by Carpinus betulus (European hornbeam), and (3) a forested microbasin dominated by Picea abies (L.) (Norway spruce). The dissolved inorganic nitrogen (DIN: NH ₄ ⁺ , NO ₂ ⁻ , NO ₃ ⁻ ) budget was examined for a period of 3 years (1991-1993). Mean annual loads of DIN along with sulfate SO ₄ ²⁻ and base cations Ca²⁺, Mg²⁺, Na⁺, K⁺, and HCO ₃ ⁻ were calculated from ion concentrations measured in stream water, open-area rainfall, throughfall (under tree canopy), and streamwater at the outlets from the microbasins. Comparison of the net imported/exported loads showed that the amount of NO ₃ ⁻ leached from the agricultural microbasin is ∼3.7 times higher (43.57 kg ha⁻¹ a⁻¹) than that from the spruce dominated microbasin (11.86 kg ha⁻¹ a⁻¹), which is a markedly higher export of NO ₃ ⁻ compared to the hornbeam dominated site. Our analyses showed that land cover (tree species) and land use practices (fertilization in agriculture) may actively affect the retention and export of nutrients from the microbasins, and have a pronounce impact on the quality of streamwater. Sulfate export exceeded atmospheric rainfall inputs (measured as wet deposition) in all three microbasins, suggesting an additional dry depositions of SO ₄ ²⁻ and geologic weathering.

Particulate matter (PM) is one of the most harmful inhaled pollutants. When PM is emitted into the atmosphere, the only possible method for cleaning ambient air is through vegetation acting as biological filters for pollutants. However, in winter periods when the concentration of PM is usually the highest, the efficiency of plants is very low. The aim of this work was therefore to examine the accumulation of PM and selected trace elements (TE) by three species, evergreen coniferous Taxus baccata L. and Pinus nigra Arn., and deciduous Carpinus betulus L. during the winter season. The highest amounts of PM accumulated on the foliage of P. nigra, while TE on the leaves of C. betulus. Most of the PM accumulated on plant foliage belonged to the large fraction size (10–100 μm) and was deposited on the surface of foliage (SPM). The concentration of four TE (Ni, Pb, Cd, and Sb) was higher in PM accumulated on foliage, while in the case of three other TE (Zn, Cr and Mg), their concentration was higher in plant tissue. The TE were recorded in all PM size fractions and were rather equally distributed between surface PM (SPM) and in-wax PM (WPM). These findings have implications for urban plantings in countries with short vegetative season, where tolerant conifer species and deciduous species which keep foliage through winter should be included in urban forest plantings due to their efficiency in the removal of pollutants from the air.

Ostrya spp. and Carpinus spp. pollen was in vitro exposed to three atmospheric pollutants: CO, O₃ and SO₂. Two levels of each pollutant were used, and the first level corresponds to a concentration about the atmospheric hour-limit value acceptable for human health protection in Europe and the second level to about the triple of the first level. Experiments were done under artificial solar light with temperature and relative humidity controlled. The viability of the exposed pollen samples showed a significant decrease. Also, the germination percentage showed a significant decrease in both exposed pollens, and the effect was most pronounced for SO₂, followed by O₃ and CO. A general decreasing trend in the total soluble protein content of the exposed pollen samples when compared with the control was observed, but it was only statistically significant for the Ostrya spp pollen. The results showed marked effects were observed on the Ostrya spp. and Carpinus spp. pollen when exposed to air pollutant levels that can be considered safe for human health protection.