FEATURES OF ADSORPTION OF PARTICULATE MATTER BY NEEDLES AND LEAVES OF TREES IN IRKUTSK URBAN FORESTS

Abstract

The pollution of natural forests preserved on the territory of the Irkutsk city was studied in terms of the level of adsorption of aerosol particles (particulate matter, PMx) by main forest-forming species of woody plants. The needles of Scotch pine (Pinus sylvestris L.) and Siberian larch (Larix sibirica Ledeb.), as well as leaves of Silver birch (Betula pendula Roth) were sampled on the laid test plots to study their sorption capacity in relation to PMx. Using the methods of scanning electron microscopy and X-ray spectral microanalysis, a wide variety of shapes, sizes, and chemical composition of aerosol particles on the surface of needles and leaves was shown. The adsorbed PMx particles were found to contain carbon, silicon, sulfur, calcium, phosphorus, chlorine, and magnesium in the greatest amount; a significant proportion of heavy metals present in the form of metallized particle accumulations, in which the metal content can reach 80%. It has been shown that aerosol particles actively penetrate needle/leaf tissues through stomata and cuticle, damaging them. With a high level of pollution by PMx, complete clogging of the stomata and heavy destruction of dermal tissues are often observed. The high level of adsorption of particulate matter by needles and leaves of trees indicates a high cleaning capacity of urban forests. At the same time, pollution with PMx particles has a powerful negative effect on physiological and biochemical processes of a tree organism, which is manifested in a sharp violation of the parameters of photosynthesis, transpiration, and inhibition of growth processes.