The destruction of the environment by the soil and area contamination with toxic elements is a novel problem due to the incredible exploitation of the industry in the whole world, finding noninvasive biological methods that preserve nature can be one of the most important tools for maintaining the health of people in areas contaminated by dangerous elements.
One of the most powerful factors of destruction of the components of the biosphere, which have a special ecological, biological and health significance, is contamination with trace, toxic, heavy metals (Be, Cd, Cr, Cu, Hg, Ni, Pb, Se, Zn, Ag, Au, Sb, Sn, Te), related to high and moderately hazardous and radionuclides, whose behavior in any ecosystem is very difficult. All changes in the anthropogenic nature disturb the natural balance of each ecosystem, having a detrimental effect on living organisms, plants, soil, water and atmosphere. The danger of subsequent pathophysiological changes in the health status of people is fraught with the growth of non-infectious pathology caused by metabolic disorders, genetic changes, mutations, deterioration of the immune and adaptive capabilities of the organism that contribute to a decrease in the level of public health and biosafety of life.
The increased consumption of energy and mineral resources, due to the growing number of vehicles, large-scale use of home appliances, the development of the heating complex and many others, leading to a steady increase in the concentrations of individual metals-trace elements, many times exceeding the permissible standards, lead to intense air pollution, soil and water in people's areas of residence. In this regard, the identification of local risk zones, the establishment of elements (heavy metals and radionuclides) polluting the investigated soil areas is very relevant.
In the Republic of Tajikistan there are highly hazardous areas of radioactive contamination, for example, near the towns of Istiklol (formerly Taboshar) and Buston, and in the region of Dehmoy, in particular, emissions of radioactive substances as of 2017 are at least 36 million tons and cover the territory of more than 80 hectares
In the last decades of the 20th century, methods for purifying the environment using cultivated and wild plants were introduced in a number of countries to improve the ecological situation, humidify air in populated areas, reduce dust and noise, bioremediation of soils, etc.
Taking into account the deterrent and absorbing capacity of individual plants, it is planned to collect and identify plant species, including medicinal plants growing in the study sites, and their botanical identification. It is necessary to carry out a comparative analysis of morpho-functional and genetic changes of plant-adsorbents, under the influence of certain metals-microelements and radionuclides growing in the studied zones with the data of published scientific research. The assessment of the impact of the components of pollution on the botanical features and physiology of plants, as well as the absorption capacity of heavy metals and radionuclides, will be carried out using physical and chemical studies on the available equipment for determining the molecular dynamic characteristics and infrared spectra, followed by quantitative determination of the metals- microelements in soil and plant samples collected from certain areas.
The ability to eliminate soil contamination with heavy metals and radionuclides using engineering technology is quite complex and requires large economic costs. In view of the foregoing, the use of phytomelioration for the purification of contaminated areas by planting plants with hyperaccumulative properties (root and foliar uptake) seems to be the most affordable, promising and cost-effective way to purify the environment. The search and study of plants that have a high tolerance and bioavailability to heavy metals, the ability to accumulate and retain them, is a very urgent problem in the conditions of the Republic of Tajikistan. The use of tolerant plants resistant to heavy metals and radionuclides, possessing sorption properties, will help in the practical solution of environmentally-friendly soil and air purification, in order to reduce the degree of environmental pollution.
Expeditions to collect samples of soils and plants from the same sections of the investigated zones are planned to be produced at least 3-5 times during the year for the analysis of the quantitative content of heavy metals and radionuclides, depending on the part of the plant and the period of collection of geobotanical features of the investigated zones. This approach makes it possible to observe and evaluate the period of maximum absorption capacity of the investigated elements by plants possessing pronounced sorption and accumulating properties. In addition, monitoring the season of maximum accumulation of heavy metals and radionuclides by plants, as well as the identification of various parts of plants that have the greatest sorption activity, will allow planning the collection periods of hyperactive accumulating plants-bioindicators. For this stage of the study, there is a need to purchase a mobile laboratory equipped with portable equipment.
Determination of the distribution radius of contamination by heavy metals and radionuclides around the investigated contamination sites is necessary to determine the safety boundaries around the risk zones, with a view to using them for growing agricultural crops for medicinal and food purposes, as well as for plants used in animal husbandry and grazing.
It is known that Tajikistan is rich in medicinal plants. There are more than 5 thousand species of higher and lower plants growing in different climatic conditions (mean annual temperature differences from -60С to + 170С with minimum and maximum values from -630С to + 470С) and ecological zones (more than 10 ecosystems with specific microclimate features) zones. Pollution of the environment with numerous domestic and industrial wastes, asphalt dust and exhaust gases, uncontrolled use of chemical fertilizers and many other factors could lead to changes in the molecular dynamics characteristics, and, consequently, the medicinal properties of medicinal plants. As a result of mixing pollutants with each other, the evaluation of the impact of each individual component of complex pollution is significantly hampered, since by entering into interaction with each other, pollutant elements increase negative effects on the living organism.
It should be noted that the influence of the features of ecology and habitats on the structure formation and synthesis of substances, the change in biological and therapeutic properties, and the spectral characteristics of medicinal plants in Tajikistan have not been studied.
Based on the results of the study, it is planned to develop proposals on methods for the ecological and low-cost purification and decontamination of soil and air pollution from heavy metals and radionuclides by sowing and growing plants that have the maximum accumulating properties. Further, the development and compilation of methodological recommendations on phytoremediation of the environment (soils, air) for managers and employees of the agro-industrial complex, relevant ministries and departments will be carried out. It is planned to organize and conduct training seminars for interested persons.
At the same time, it is planned to study possible ways of safe collection, storage and utilization of vegetation that accumulates toxic heavy metals and radionuclides during the maximum sorption of elements.
An analysis of the botanical features and a comparative characteristic of the content of heavy metals and radionuclides in various parts of plants, including medicinal ones, growing in ecologically clean regions and similar plants growing in the places of pollution of various geobotanical zones of the Republic of Tajikistan will be carried out.
In connection with the foregoing, the purpose of the project is to find plants that are able to drain toxic metals in suspect regions, to determine plants with hyper accumulating properties.
To reach this goals, the following tasks will be undertaken:
1. The plants that grow in different regions of Tajikistan will be collected (n=400).
2. The plant in which different methods of analysis (Complex IR Fourier spectrometer based on Nicolet 5700 manufactured by Thermo Electron (USA) and Analytical Scales Model PG272SAV "Shimadzu" AX-120 scales) of the presence of toxic metals such as (Co, Cr, Cu, Ni, Pb, Zn, As, Sr, V) both in the soil they grow and in the root, truncates and leaf, will be identified.
3. The seed of these plants will be grown (in vitro) in the sole with and without metals.
4. The selected plants will be grown in large quantities to collect the seeds for experimentation in the real contaminated areas. We are going to validate the results after careful analysis of the plants for their capacity of absorption in toxic metals.
5. Once the best plants and their corresponding toxic metals are identified, this concept can enter the industrial phase.
