Investigating the Effects of Atmospheric Gaseous Pollutants on the Vegetation of Nezahat Gökyiğit Botanical Garden in Istanbul, Turkey: A Case Study and Survey

We assessed the effects of gaseous air pollutants on the vegetation of the Nezahat Gökyiğit Botanic Garden in Istanbul, Turkey, based on the physiological responses of common specie Fraxinus angustifolia as it is the most common type of tree located all around the Garden. In order to assess the level of air quality, sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) concentrations were measured. The results clearly show that the region, in general, has been identified as under the significant impact of NO2. The leaf samples of Fraxinus angustifolia were collected during the period of plant growth months (May, June, August, September), and heavy metal content, water content and photosynthetic pigment analysis were performed in leaves tissues, such as chlorophyll a, chlorophyll b, total chlorophyll, carotenoid amount (µg g-1). Heavy metals accumulation on the leaves were observed at the locations close to the main roads.

Average total chlorophyll content observed in generally 87 ± 10 mg g-1 fresh weight (mean ± SD) level. A statistically significant relationship between NO2 level and photosynthetic activity, total chlorophyll content and carotenoid has been identified. As the NO2 level increases, increase of photosynthetic activity, chlorophyll a and b and total chlorophyll content and decrease of carotenoid levels were observed. Although the level of air pollution variations over the sampling points have been determined during the growth phase of the plant, Fraxinus angustifolia plant species located all around the garden showed resistance to air pollution.