CHANGE OF BIOGEOCHEMICAL INDEXES IN PINE FORESTS UNDER TECHNOGENIC POLLUTION
Studies of <i>Pinus sylvestris</i> L. forests in the impact (5-10 km) and buffer (11-40 km) technogenic pollution zones in the vicinity of a large industrial centre Usol'e-Sibirskoe of Irkutsk Oblast have been conducted in 2013-2016. Changes of biogeochemical indexes (acid-base balance, accumulation and migration of pollutants and biogene elements) in the components of a forest ecosystem, such as pine trees, organic litter, and soil horizons were determined. It has been shown that the displacement of acid-base balance to the alkaline range and the active migration of pollutant elements in soil horizons and organic litter are the key processes that cause the violation of the exchange reactions of the Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup>, Na<sup>+</sup> cations in a soil absorbing complex as well as decreasing the migration of nutrient elements to the root systems of pine trees. The pronounced changes in the acid-base balance, the high accumulation of pollutant elements, binding of biogenic elements by pollutants in the horizons of soil profiles and plant tissues lead to the disruption of nutrition and inhibition of growth processes in pine trees. The biogeochemical indicators under study are characterized by interconnected changes in the components of the forest ecosystem and can serve as adequate criteria for assessing its state under technogenic pollution. Therefore, the obtained results provide information on the nutrient cycling in pine forests, role of industrial emission elements, their migration and accumulation in individual components of the ecosystem.