Mukhambetkali Burkitbayev

Uranium series radionuclides in surface waters from the Shu river (Kazakhstan)

The concentrations of (238)U, (234)U, (226)Ra, (210)Po and (210)Pb have been determined in surface waters collected along the course of the Shu River, lying on the border between Kazakhstan and Kyrgyzstan. In the study area, the river runs through some of the largest uranium deposits worldwide, which were actively exploited during the nuclear weapons and nuclear energy programmes of the former Soviet Union. The data show an increasing trend in uranium concentrations downstream the river from the city of Tokmak to the city of Shu, with good correlation between total uranium concentrations and total dissolved solids. Data on uranium isotopes disequilibrium show the presence of technogenic uranium inputs into the Shu River downstream from the city of Karasu, evidenced by a decrease in the measured (234)U/(238)U isotopic ratio from 1.63 in uncontaminated sites to 1.29 in sites affected by past mining activities.

Uptake of uranium, thorium and radium isotopes by plants growing in dam impoundment Tasotkel and the Lower Shu region (Kazakhstan)

Abstract The activity concentrations of isotopes of uranium, thorium and radium-226 in dominant species of plants (Xantium strumarium, Phragmites communis, Artemisia nitrosa and Artemisia serotina) growing on the territories contaminated by uranium industry of Kazakhstan (close to dam impoundment Tasotkel and the Lower Shu region) are presented. The obtained data showed the significant variations of activity concentrations of isotopes of uranium, thorium and radium-226 in above ground parts. The concentrations of most of the investigated radionuclides in the root system are higher than in the aboveground parts; it can be explained by root barrier. It was found that the highest root barrier has Xantium strumarium, especially for uranium isotopes. The concentration ratios of radionuclides were calculated, and as the result it was found that the highest accumulation ability in the investigated region has Artemisia serotina.

Ecological Impacts of Large–Scale War Preparations: Semipalatinsk Test Site, Kazakhstan

Development and testing of weapons of mass destruction may result in irreversible environmental changes resulting in high social risk and negative effects on human health. The former Semipalatinsk nuclear test site (STS) is a sorrowful monument of the Cold War. Nuclear tests at STS inflicted numerous economic, social and ecological problems on Kazakhstan. In the framework of the NATO “Science for Peace Program,” about 1,400 km2 of the STS have been investigated. According to the results of the Semirad project, the most contaminated area of the southeastern part of the STS is two craters, Telkem-1 and Telkem-2, formed by nuclear explosions. These craters are contaminated with the fission products, cesium-137 and strontium-90, and with components of nuclear fuel, plutonium-239 and americium-241, and the activation product, europium-154. The considerable migration of radionuclides in the 40 years since the tests were conducted was not detected. The calculated effective dose for adults from radionuclides at the Telkem craters is approximately 7 mSv. In the northern part of the STS (Semirad 2 project) the most contaminated sites are located close to the area of radiological dispersion device tests. Annual effective doses from plutonium-239 and strontium-90 can reach over 8 mSv. There is no possibility to detect the dose, largely from micron-sized “hot particles” of high radioactivity spread across the STS territory. The STS is a unique scientific preserve where scientists from all over the world are welcome to conduct research. The Republic of Kazakhstan abandoned its nuclear arsenal and opened the path to the international community to a world free of nuclear weapons.

Assessment of the main natural radionuclides, minor and trace elements in soils and sediments of the Shu valley (near the border of Kazakhstan and Kyrgyzstan)

New data on the concentrations of the main gamma-emitting radionuclides, minor and trace elements, and isotopes of uranium (with Ra-226 as a daughter product of U-238) and thorium in soils and sediments of the Shu valley (from the river Chon-Kemin to the river Kuragatty downstream the river Shu) are presented, determined by high-resolution gamma-spectrometry, k0-instrumental neutron activation analysis and alpha-spectrometry with appropriate radiochemical separations of the samples, respectively. The results obtained showed an aquatic migration pathway of most of the trace elements and radionuclides and predicted water pollution downstream the river Shu. The scandium method showed pollution by As, Br, Ca, Cr, Zr of the Tasotkel dam impoundment and by Ca and Cr of the river Shu below its confluence with the river Kuragatty. According to the disequilibrium isotopic method for uranium (using the isotopic ratio U-234/U-238), areas with accumulation and leaching processes were estimated for soils and sediments of the river Shu and its main inflows.

Heavy metals and natural radionuclides in the water of Syr Darya River, Kazakhstan

This study deals with concentrations of heavy metals and the main uranium series radionuclide in the Syr Darya surface waters (Kazakhstan). Large proportion of studied heavy metals were transported with suspended matter (> 0.45 μm), while large proportion of U (98–100 %) and Mo (81–100 %) were in dissolved forms and colloidal fraction (< 0.45 μm).

STRONTIUM-90 CONTAMINATION WITHIN THE SEMIPALATINSK NUCLEAR TEST SITE: RESULTS OF SEMIRAD1 AND SEMIRAD2 PROJECTS - CONTAMINATION LEVELS AND PROJECTED DOSES TO LOCAL POPULATIONS

Analysis of strontium-90 in soils showed that most of the SEMIRAD1 and SEMIRAD2 project areas were little contaminated with this radionuclide indicating that the extensive testing of nuclear devices at the STS (including more than 100 groundlevel, aerial and crater-producing explosions) resulted in little dispersed local contamination by fission products, including strontium-90. However, local strontium-90 contamination produced by the Telkem, crater-producing explosions within the SEMIRAD1 study area was evident at distances less that about 3 km from the explosion sites. Within the craters soil strontium-90 concentrations reached 1 kBq kg -1 . Around the craters strontium-90 was more widely dispersed than fuel-associated radionuclides and evidence exists to suggest that it is much more mobile within the environment. Within the SEMIRAD1 study area strontium-90 levels were also elevated below the path of the fallout plume produced by the testing of the Soviet Unions first H-bomb in 1953. Radiation doses to residents of the SEMIRAD1 study area were calculated using a modified ECOSYS model. These indicated that strontium-90 was a major contributor to dose in the more contaminated regions around Telkem and close to the village of Sarzhal. Annual doses to adult males living close to Telkem were assessed to currently be about 7 mSv, but these were predicted to fall in line with the physical half-life (28.64 years) of strontium-

Coprecipitation of Nanocomposites Based on Colloidal Particles of Sulfur and Carbonates of Alkaline-Earth Metals from Polysulfide Solutions

It has for the first time been shown that the action of carbon dioxide on solutions of alkaline-earth metal polysulfides causes a reaction yielding nanoparticles of sulfur and calcium, barium, and strontium carbonates. It has been found that, initially, particles of sulfur and a corresponding carbonate are synthesized with average sizes of about 20–25 nm; then, the particles are enlarged (aggregated) with the precipitation of a composite, which consists of hydrophobic particles of sulfur and the carbonate (the latter become hydrophobic due to the adsorption of neonol present in the reaction mixture). It has been shown that only sulfur exhibits antifungal activity in the composites, while carbonates have no effect on pathogenic fungi. The composite consisting of sulfur and calcium carbonate nanoparticles has shown the highest biological activity during germination of wheat seeds.

Mechanochemical synthesis of colloidal silver bromide particles in the NaBr–AgNO3–NaNO3 system

X-ray diffraction and thermal analyses, electron microscopy, and dynamic light scattering have been employed to study silver bromide nanoparticles obtained by the mechanochemical exchange reaction NaBr + AgNO3 + zNaNO3 = (z + 1)NaNO3 + AgBr in sodium nitrate matrix (diluent and side reaction product) at z = z1 = 8.06 and z = z2 = 4.31. AgBr nanoparticles have been obtained in the free form by dissolving the matrix in water, and their activity in the photodegradation of methylene blue dye has been studied.