Accumulation of sulfur and glutathione in leaves of woody plants growing under the conditions of outdoor air pollution by sulfur dioxide

Abstract

In the course of human industrial activity, atmospheric air is polluted by gaseous pollutants, among which sulfur compounds, and sulfur dioxide (SO2) in particular, play a key role. Vegetation is a universal filter that is capable, in conjunction with certain technical facilities, of protecting the environment from pollution by the ingredients of industrial emissions. The purpose of this work is to determine the level of accumulation of sulfur and glutathione in the leaves of woody plants growing in the areas of sanitary protection zones of enterprises of the city of Zaporizhzhya in order to develop recommendations for the creation of an effective biofilter. The objects of the study were the woody plant species growing in the area of protective plantations of a number of enterprises in Zaporizhzhya: RE Zaporizhzhya Titanium & Magnesium Combine, Zaporizhzhya Aluminium Plant PJSC, Zaporizhzhya Abrasive Plant PJSC, Zaporizhstal PJSC, Zaporizhzhya Ferroalloy Plant PJSC, Zaporizhvohnetryv PJSC, PrJSC "Ukrgrafit" and Zaporizhtransformator PJSC. The control area was a forest belt located 12 km away from the source of pollution. At each site 5 model trees of a given age category of each species were selected. The leaves needed in order to determine the sulfur content were taken from the south-eastern side of the crown at a distance of 2 m above the soil surface under the same lighting conditions. We have established that the accumulation of sulfur in leaves of woody plants which grow under the conditions of outdoor air pollution by sulfur dioxide (SO2) occurs during the entire vegetation period, with the young leaves that have just finished growing being the most affected. The maximum amount of sulfur is observed at the end of the growing season. The greater concentration of sulfur in the leaves of woody plants in the areas of sanitary protection zones of industrial enterprises is linked to the higher level of gaseous pollutant emissions in the atmosphere of a given enterprise, but the degree of increase in the content of the pollutant in the leaves of plants of various protective plantations is not proportional to the quantitative indicators of the level of sulfur dioxide (SO2) in the air. Woody plant species were divided into three groups according to the amount of sulfur accumulated in their leaves: І – the maximum level – Betula pendula, Tilia cordata, Salix alba, Robinia pseudoacacia, Populus alba, P. simonii, P. nigra, ІІ – medium – Acer platanoides, A. negundo, Fraxinus lanceolata, Catalpa bignonioides, ІІІ – the smallest – Morus alba, Ailanthus altissima, Elaeagnus angustifolia and Ulmus carpinifolia. The increase in sulfur content in the leaves of woody plants growing in the area of sanitary protection zones is consistent with the increase in glutathione content compared to our control parameters, which is not only of high physiological significance, but its formation can also be one of the ways of metabolizing this element. The obtained results can be used for the development of recommendations with the purpose of selecting the assortment of woody plants for the reconstruction of green plantations growing in the area of sanitary protection zones of enterprises. In a subsequent study, the accumulation of gaseous pollutants such as chlorine and phenol in the leaves of woody plants growing in and around protective forest belts will be examined.