Content of cesium radionuclides in water and bottom sediments of the Barents sea

Based on the results of field research in the cruise 68 of the RV Akademik Mstislav Keldysh, the content of anthropogenic 137Cs radionuclides in surface waters and bottom sediments of the Barents Sea was estimated. As a result of a comparative assessment of current levels of radiocesium in other seas, it is concluded that the radioecological situation in the Barents Sea is favorable, despite the presence of a large number of potential sources of radiation pollution.

Electrochemical Sensing and Removal of Cesium from Water Using Prussian Blue Nanoparticle-Modified Screen-Printed Electrodes

Selective screening followed by the sensing of cesium radionuclides from contaminated water is a challenging technical issue. In this study, the adsorption functionality of Prussian blue (PB) nanoparticles was utilized for the detection and efficient removal of cesium cations. An efficient PB nanoparticle-modified screen-printed electrode (SPE) in the three-electrode configuration was developed for the electrochemical sensing and removal of Cs+. PB nanoparticles inks were obtained using a facile two-step process that was previously described as suitable for dispensing over freshly prepared screen-printed electrodes. The PB nanoparticle-modified SPE induced a cesium adsorption-dependent chronoamperometric signal based on ion exchange as a function of cesium concentration. This ion exchange, which is reversible and rapid, is associated with electron transfer in the PB nanoparticle-modified SPE. Using this electrochemical adsorption system (EAS) based on chronoamperometry, the maximum adsorption capacity (Qmax) of Cs+ ions in the PB nanoparticle-modified SPE reached up to 325 ± 1 mg·g−1 in a 50 ± 0.5 μM Cs+ solution, with a distribution coefficient (Kd) of 580 ± 5 L·g−1 for Cs+ removal. The cesium concentration-dependent adsorption of PB nanoparticles was also demonstrated by fluorescence spectroscopy based on fluorescence quenching of PB nanoparticles as a function of cesium concentration using a standard fluorophore like fluorescein in a manner analogous to that previously reported for As(III).

Sorption of 90Sr and 137Cs on clays used to build safety barriers in radioactive waste storage facilities

The purpose of the work was to investigate the sorptive capacity of natural clay samples with respect to 90Sr and 137Cs to assess the possibility of using these as components of protective barriers at radioactive waste isolation facilities. Bentonite clays of the Zyryanskoye and Desyaty Khutor deposits and high-melting clay of the Kampanovskoye deposit were selected for the investigation. The capacity of clays for sorption through ionic exchange is characterized by the value of the cation exchange capacity (CEC). In the process of sorption experiments, all of the test clays displayed a high rate of extracting strontium and cesium radionuclides from aqueous solutions. It was shown that the sorption of 90Sr is affected by the content of montmorillonite in the samples: bentonite clays absorb up to 98–99% of the initial radionuclide content in the solution, while about 80% of strontium is sorbed by high-melting clay. Cesium is practically fully sorbed by the tested samples and the degree of sorption amounts to over 99%, the highest value of the distribution coefficient having been recorded for the Kampanovskoye sample (Kd = 5.0×103 cm3/g). The method of sorbed radionuclides fixation on the clay samples were identified by selective desorption using the modified Tessier methodology. It was shown that strontium ions are more mobile than ions of cesium up to 97% of which is retained by clays.

Purification of water and fertile soil with bentonite-like clays of the Belgorod Region

This paper presents the results of a comparative assessment of the effectiveness of sorption purification of aquatic medium and fertile soils using native forms of bentonite clays of deposits in the Belgorod region (Russia) from heavy metal ions (Cu2+, Fe3+, Cr3+, Pb2+) and radionuclides (137Cs, 85Sr, 233U и 239Pu). It was revealed that during the sorption of heavy metal ions (Cu2+, Fe3+ и Cr3+) from model water systems, the most absorbing activity is shown by the natural clays of the Polyana and Nelidovka deposits, which have almost the same ability to absorb heavy metal ions. The purification efficiency of the model aqueous solutions from these cations taken at an initial concentration of 0.1 mmol/l reaches 95%. It was established that the natural clay of the Polyana deposit is also an effective sorbent for the purification of solutions from cesium radionuclides. In terms of sorption ability, the studied sample is 5 times superior to natural clinoptilolite, which is most often used to purify solutions from radiocesium.. It was revealed that with an increase in the amount of added sorbents, the detoxification effect is increased, that is, the content of heavy metals in the green mass decreases.

Internal doses to the public in the Fukushima prefecture from the Fukushima Daiichi NPP accident

The article is devoted to the analysis of internal dosimetry in residents of Fukushima Prefecture due to the accident at the Fukushima-Daiichi NPP. On March 24-30, 2011, screening studies were conducted on measurements of 131I content in thyroid gland of children in those municipalities where the Japanese program for assessing the radiological consequences of the radiation accident “SPEEDI” predicted doses in the thyroid of one-year children from 100 to 500 mSv. Among 1080 children measured, 55% had results below the background, and the maximum estimate of the equivalent dose in the thyroid was 43 mSv. Measurements of several dozen inhabitants with other instruments and methods confirmed low levels of 131I in the thyroid. In total, the 131I thyroid direct measurement database of Fukushima residents contains approximately 1300 individuals. 75% quartile of individual thyroid dose distributions was below 10 mSv, the median was from 0 to 3.7 mSv among children aged from 0 to 15 years in the five examined municipalities. The contribution of short-lived iodine radionuclides was estimated as 15% of the dose from 131I for the main radioactive release on March 15. The effective dose of internal exposure to cesium radionuclides ( 134Cs + 137Cs), estimated from 10 thousand whole body measurements for the first year after the accident, was below 0.1 mSv in 90% of the examined people. Whole body measurements of children 6-15 years old in the second year after the accident confirmed the values of the effective dose of internal exposure less than 0.1 mSv, while the estimates of the effective dose of external exposure in the same children with using individual dosimeters determined the median distribution as 0.66 mSv with a maximum value of 3.45 mSv . The measurement results do not provide any basis to expect a future increase in the incidence of thyroid cancer and other radiogenic diseases among the Fukushima residents. Preventive evacuation of the population before the radioactive release, stay in enclosed dwellings, strict radiation control of food products have effectively reduced the expected doses of internal exposure to residents. In the predictions of the radiological consequences of the accident, it is necessary to take into account the actually implemented measures to protect the population, and local characteristics of the style of life and living.

Natural Zeolites of Eastern Transbaikalia in Technologies for Mining Enterprises Wastewater Treatment

The possibilities of conditioning acidified wastewater from mining enterprises by natural zeolites of deposits in East Transbaikalia were studied. Sorption characteristics of various natural and synthetic zeolites in relation to strontium and cesium radionuclides were determined to evaluate the possibility of their application for the purification of radioactively contaminated technogenic and natural waters. The ability of natural zeolites to selectively adsorb the heavy metal ions was investigated. An experimental study was made on the possibility of neutralizing acidic media with zeolites. The kinetic dependencies were obtained to evaluate the ion exchange rate on the natural zeolites. The impact of exchanging cations and the defining mineral’s structure on the exchange rate was studied. The instantaneous adsorption interaction rate values were determined. The possibility of 90Sr and Ca2+ ions sorption from the simulated solutions of industrial wastewater was investigated.

Surface Functionalization of Mesoporous Carbon for the Enhanced Removal of Strontium and Cesium Radionuclides

Mesoporous carbons (MPC) and modified mesoporous carbons (MMPC) were prepared from asphalt for the adsorption of several metal ions from the aqueous solution. In this study, we investigated the adsorption efficiency of Cesium (Cs+) and Strontium (Sr2+) ions using mesoporous and modified mesoporous carbons. The optimum conditions for the removal of Cs+ and Sr2+ were at 10.0 pH, 1.00 ppm (1000.0 µg/L) concentration, 20.0 min contact time, 0.20 g/L adsorbent dose, 25.0 °C temperature with more than 95.0% removal of Cs+ and Sr2+ ions using MMPC. The limit of detection (LOD) was found to be 0.030 ppb and 10.00 ppb for Sr2+ and Cs+ metals ions, respectively, while the Limit of quantification (LOQ) was calculated to be 0.10 ppb for Sr2+ and 35.00 ppb for Cs+ metals ions. The functionalization of the MPC was performed using potassium permanganate to get MMPC, which were characterized by FT-IR spectroscopy. The nature of the X-ray diffraction peaks suggests that the MPC and MMPC carbons are amorphous and semi-crystalline materials. The scanning electron microscope (SEM) and transition electron microscope (TEM) studies showed the changes in the morphology due to the adsorption on the surface of the carbons. The TEM analysis clearly showed that the metal ions blocked most of the pores on the surface. The surface area, by N2 adsorption isotherm (BET), of MPC and MMPC were 937 and 667 m2·g−1, respectively. Among the adsorption isotherms, Langmuir isotherm showed the best linearity. The Langmuir isotherm indicates that the adsorption is monolayer and homogeneous with a finite number of ions. Adsorption kinetics showed better linearity with pseudo-second-order plots and obeys this order. This process indicates that the chemical interaction, such as covalent or ionic bonding, took place between the metal ions and the carbon adsorbents.