Intensity of lipid peroxidation processes and state of tree plantations under heavy metal pollution

摘要

The processes of lipid peroxidation induced by heavy metals in leaves of woody species under the influence of an industrial enterprise were studied. In the assimilation organs of Populus italica, a high accumulation of most compounds of heavy metals was found (intratissue contamination was over five-fold higher than in the control), with zinc as the most abundant metal. Aesculus hippocastanum in the zone of severe pollution most actively accumulated nickel, while Betula pendula accumulated cadmium. At early stages of leaves development, high rates of intratissue contamination were observed for all species. In the leaves of P. italica, during their morphogenesis, the level of secondary peroxidation products (TBA-active compounds) was lowest among the studied species and did not exceed the control values by more than 1.8 times. This is apparently due to increased intensity of functioning of antioxidant enzyme systems, such as glutathione and ascorbic (Halliwell-Asada cycle), and high phytochelatin and metallothionein biosynthesis in leaves, which stipulate its highest physiological stability to altered environment. Instead, in the leaves of A. hippocastanum and B. pendula with low levels of accumulation of most heavy metals, the content of TBA-active products increased 2.7 and 2.9 times, respectively, comparing to the control. It has been shown that plantations of P. italica in industrial conditions were relatively stable with a total score of assimilation organs, branches and trunk damage up to 1.3, while in A. hippocastanum and B. pendula a longterm effect of pollutants at monitoring sites resulted in 25–40% of leaves damaged by necroses and chloroses. Skeletal branches of both species were affected by rot, crown rarity reached more than 40%, and frost cracks 20–25% larger than in the control occurred. Aesculus hippocastanum and B. pendula are characterized by an unstable qualitative state of 30–60% of individuals which are at various stages of dying or significantly depressed