THE PROBLEM OF HEAVY METAL ACCUMULATION BY FLORA IN CONDITIONS OF INTENSIVE LAND USE

Abstract

The article addresses the pressing problem of heavy metal accumulation in cultivated and wild flora against the background of intensive land use and increasing agrochemical load on soils. An overview of modern sources of cadmium, lead, chromium, mercury and other toxic elements in agroecosystems is presented, in particular because of long-term use of mineral fertilizers, pesticides and land reclamation agents, as well as contamination originating from transport and industrial emissions.

The migration paths of heavy metals in the soil-plant system are considered, their bioavailability, root absorption, transport to above-ground organs and accumulation in the crop. It is demonstrated that the intensity of metal accumulation depends on the physicochemical properties of the soil (pH, organic matter content, and granulometric composition), plant nutrition conditions, and their biological characteristics.

Based on summarised experimental data, the influence of elevated concentrations of heavy metals on the morphological and physiological and biochemical indicators of plants is demonstrated. Under cadmium exposure, the degree of suppression of photosynthetic activity, a decrease in the content of chlorophyll and protein in Lathyrus oleraceus plants is highlighted. Dysfunctions of the main metabolic processes and a decrease in crop productivity due to pollution by technogenic agents are also indicated.

Attention is paid to monitoring and bioindication methods as means of assessing the state of the agro environment. The feasibility of using agricultural crops and segetal vegetation as bioindicators of the level of pollution is substantiated, as well as the use of bioconcentration and transport coefficients for quantitative assessment of the probability of metals getting into food chains.

It is concluded that the problem of heavy metal accumulation is complex and requires a synthesis of agrochemical, physiological-biochemical and ecological research. Promising directions include the development of models for predicting the accumulation of metals in the crop, the improvement of agroecological monitoring methods, and the implementation of measures aimed at reducing the bioavailability of toxic elements in soils and minimising their transfer to finished products.