Remediation of Cs-contaminated soils through regulation 134Cs and 137Cs soil-plant transfer by polymeric sorbents
Project Status: 8 Project completed
Commencement Date: 01.06.2013
Duration in months: 24 months
Objective
Project goals: To provide new procedures and development of technology for remediation of Cs-contaminated soils with different contamination levels through regulation of biological migration of 134Cs and 137Cs by polymeric sorbents in the water – soil – plant systems.
Proposed project is directly related to the “Call for proposals for projects related to land decontamination and monitoring in view of the Fukushima Nuclear Power Plant Accident” and belongs to ''Decontamination and rehabilitation technology areas'' covered by the Call: Technologies for decontamination of soils (areas of habitation and farming); Technologies for fixing radionuclide to prevent further migration.
In the science and practice there are known countermeasures (agronomic and agrochemical protective measures) to reduce the transfer of radionuclides (RN) from soil to plants - liming, fertilization, selection of crops and varieties. According to the literature the application of countermeasures in the first years after the Chernobyl accident (1987-1992) provided reduction of 137Cs in agricultural crops 3-8 times. Effectiveness of protective measures has significantly reduced in the next period after the accident (1992-2005) - by an average of 20-50%.
In case of Fukushima, it also requires the use of countermeasures, particularly in the early years. Also the structure of soil in the contamination area must be considered.
After the accident at the Chernobyl Nuclear Power Plant research and practice agriculture in Russia and Belarus have fully confirmed the important ecological function of potassium - as an antagonist to the radiocesium.
This project proposes new countermeasures to Fukushima, namely, the use of polymeric sorbents, in particular based on potassium ion. The task of the Project to remediate Cs-contaminated soils by regulation of RN migration will be achieved by varying the counter ions in a polymer polyelectrolyte. Polymers proposed in the Project are capable to absorb the ion of one metal more efficiently than ions of other metals. Chemical binding with the copolymer hinders leaching of radioactive metal, preventing migration of RN to deeper soil layers and ground waters and decreasing contamination of the environment.
In the scope of previous ISTC A-1671 project the research team has developed new means for remediation of RN-contaminated soils through regulationof biological migration of anthropogenic RN particularly, 137Cs and 90Sr by adding water-retaining polymers to the ecosystems “water– soil– plant” and “water– nutrient solution–plant” in the zones of high radio-ecological tension. The field tests demonstration proved that water-retaining polymers can regulate radionuclides's transfer in the system “water-soil-plant” but developed technology needs further improvement.
The project addresses following issues:1. Development of methods for the synthesis and study of the properties of highly effective polymer-sorbents of RN from the soil; 2. Assessment of the effectiveness of polymers on growing plants in the zones of low and high radioecological tension.
For Project implementation it is planned to perform synthesis, radio- and agrochemical, biological studies, in particular:
- Synthesis of polymeric sorbents
- Obtainment of compositions on the base of inorganic fillers
- Study properties of synthesized materials
- Study the influence of polymer’s type on:
- productivity of plants (control-without polymer applying).
- rate of irrigation
- migration and accumulation of 134Cs and 137Cs in different soil layers (0-5; 5-10, 10-20), under-ground and over-ground parts of plants.
- redistribution of radionuclides in water – soil – plant and water – nutrient solution – plant systems
- residual irrigation water radioactivity after passing through vertical slit of soil.
- Evaluation of co-growing system of food-plants and hyperaccumulator-plants on the soil-plant uptake of 134Cs and 137Cs.
- Verification of Cs-absorbance ability of different polymers after using them for plants growing.
One of important aspects of the problem related to contaminated soils remediation is elaboration of protective actions aimed at reduction of biological migration of RN in systemwater – soil – plant. The proposed Project mainly aims to achieve control on transfer of RN in systemswater – soil – plant and water – nutrient solution – plant due to counter ions variation in the polymeric sorbents.
Other task of this project is to develop polymer sorbents of RN from the soil. Most of the known polymer sorbents for water purification have a number of disadvantages: high sensitivity to changes in the ionic composition and pH of the solutions, low strength of materials and inability to manufacture products specified form. Therefore, the project is planned as a modification of the polymer matrix and use of inorganic fillers. Addition of different type filling materials and variation of their concentration will allow achievement of the desired balance of physical and chemical properties in the final composite material.
Expected results will provide a new approach for remediation of Cs-contaminated soils with different contamination levels by RN uptake and their accumulation in plants/polymers and simultaneous production of ecologically sound biomass consumed for food. The research results based on scientific and technological knowledge can be successfully used for overcoming and elimination of the catastrophic consequences of Fukishima-1 NPP nuclear accident.
Project related methodology includes known methods and methods developed by the team researchers for the synthesis of polymers, determination of RN in soil, water and plants, methods for plants growing in hydroponics and in soil.
In accordance with the aims of the ISTC during the implementation of this project the tasks will be performed to re-orient the activity of scientists earlier engaged in the sphere of defense research and industry towards the solution of problems relevant to environmental protection; to integrate Armenian scientists into the international research collaboration; to provide assistance in solution of national and international problems on protection and remediation of lands.
The role of Foreign Collaborators might include rendering methodic recommendations on radionuclides determination, joint discussions of research findings and information exchange in the course of Project implementation, providing comments to technical reports, joint publications.
Participating Institutions
LEADING
Institute of Hydroponics Problems
PARTICIPATING
Yerevan Institute "Plastpolymer"
COLLABORATOR
Korea Atomic Energy Research Institute (KAERI)
COLLABORATOR
Brookhaven National Laboratory
COLLABORATOR
Research Center for Exotic Nanocarbons (ENCs), Shinshu University
