Physiological factors into plant uptake models for pollutant

The main principles of biological control of the intensity of pollutant flow into system soil-plant have been analysed. It demonstrated that functional state of plants is so far significant factor in determination of rate of pollutant turn on trophic chains as physical-chemical property of mineral elements Most biosphere and contamination assessment models are based on uniform soil conditions,since single coefficients are used to describe the transfer of contaminants to the plant. The main pathway of the functional control intensity of pollutant flow such as possibility of plant to increase mobility of mineral elements into soil and change of ion's exchange characteristics of plant tissues, which determine the degree of attraction and capacity of accumulation of non biogenic elements by a plant have been considered. It is known that there are two groups of factors which determine the level of pollutant accumulation by plant. The first group is connected with determination of the level of biological availability of pollutants for a plant in soil, the second group of factors determine attractive of the higher plants and capacity of radionuclides and heavy metals accumulation in biomass. At the same time in accordance with modern eco physiological data, different alive organisms can play active part in processes of the mineral elements migration. Metabolites of the coil microorganisms and especially root excretion of higher plants. Our investigations carried out earlier demonstrated that there is high correlation between the level of Cs, Cu, Zn and Co accumulation and cation exchange capacity of the intact plant tissues and on the other hand similar changes of these characteristics in condition of the experimental modification of radionuclide and heavy metals accumulation by different environmental factors. These data suggest that namely cation exchange capacity may be one of the main 'driving force' and physiological characteristics in absorption of non biogenic elements. The investigation was carried out in a conditions of laboratory experiment. Samples for each type of experimental measurements and biochemical investigation have been obtained from oat and pea seedlings of 12 days grow. Root and stem biomass and cell walls CEC was determined the method involved saturation of the tissues with H+ ions with 1 M KCl at pH7. The quantity of H+ ions displaced from the tissues by 1 M KCl being calculated from the change in pH-meter. Cell walls were extracted using the method of Stessard. The estimate the kinetic and concentration regularities of the Cs, Cu, Zn and Co absorption 'material' with concentration 10-5 - 10-3. Concentration curves were plotted on the base of the family of the kinetic curves by means 'zero' rate principle so to say the rate of mineral element uptake by plants at the beginning of these processes. The results of our investigation indicate that the kinetic curves have complex structure and are combination of tree or more phases. It is well known that kinetic methods are widely used in the investigation of the compartmentalization of the macro- and trace elements in plant tissues. When each phase of the kinetic curve associates with intake of chemical elements in definite plant compartments. The first phase is reflection of superficial absorption by root and usually has duration from 5 to 15 min. The second phase corresponds to transfer of ions to free space and saturation of apoplast and has duration usually from 1 to 3 hours. The third phase corresponds to active, metabolic-dependent absorption and transfer off ions from apoplast to simplistic space The fourth phase is reflection of the ions. Modern experimental data on kinetics of the ions transfer from root to stem are very limited. At barley intact seedlings lag-phase has been observed as a long enough retention of this process. At the same time in accordance with results of other authors potassium translocation from root to the shoot has been realized during very shot time, that is in several seconds. Different CEC and the level of accumulation for pea and oat was demonstrated in the experiment. Present data suggest, that biological factors are powerful lever of the control of the pollutants availability and accumulation and may be taken into account under development of the modern transfer model (authors)