Determination of plutonium in environmental samples by controlled valence in aniion exchange

Separation of anthropogenic radionuclides from aqueous environment using raw and modified biosorbents

In this study, two types of biosorbents were used to remove ¹³⁷Cs and plutonium isotopes from aqueous solutions - moss (Ptilium crista - castrensis) and oak sawdust (Quercus robur), both in the form of natural and modified state. Sorbent modification significantly increases the sorbent surface area (for moss sorbents - from 4.0 to 47.2 m²/g, and for sawdust sorbents - from 1.1 to 26.3 m²/g), pore volume (from 10^-3 to 10^-2), concentration and amount of basic cations and anions, as well as active functional groups on the sorbent surface. The main functional groups on the surface of natural sorbents modified with iron hydroxide interacting with analytes are carboxyl and hydroxyl groups. For carbonized sawdust and its subsequent activation with concentrated HCl, in addition to carboxyl and hydroxyl groups, acetyl groups also become active. Carbonated sawdust treated with HCl showed the highest average removal efficiency and sorption capacity for radiocesium and plutonium isotopes in laboratory column experiments - for ¹³⁷Cs ∼78.6% and ∼196.6 Bq/g and for ^239+240Pu ∼83% and ∼41.5 Bq/g, respectively. The moss and moss modified with iron hydroxide also showed good properties of adsorbing plutonium isotopes in field (in-situ) experiments. The best results on the sorption of ¹³⁷Cs in field experiments were shown by carbonated sawdust activated with HCl, and for isotopes of plutonium - the raw moss and moss modified with iron hydroxide. The results of the study showed that sorbents can be used not only for purification of water from plutonium isotopes but allow the operational sampling and more accurate measurement of radiocesium and plutonium isotopes in the fresh water reservoirs by the dynamic flow method.

Radioactive contamination of the soil-plant cover at certain locations of Primorsky Krai, Sakhalin Island and Kamchatka Peninsula: Assessment of the Fukushima fallout

The contamination densities of soil-plant cover at certain locations within the Primorsky Krai, Sakhalin Island and Kamchatka Peninsula attributable to ⁹⁰Sr, ¹³⁷Cs and ^239,240Pu were 500-1390 Bq m^-2, 980-2300 Bq m^-2 and 37-74 Bq m^-2, respectively. These values do not exceed average global background levels, typical for mid-latitudes of the Northern Hemisphere. The spatial distribution of radionuclides depends on the climatic conditions of the region. A positive dependence of the ⁹⁰Sr and ¹³⁷Cs contamination densities, as well as additional ¹³⁷Cs from NPP "Fukushima" in the soil, was determined based on the sum of annual atmospheric precipitation within the study areas. No trends in the spatial distribution of Pu isotopes were observed. The ¹³⁷Cs contribution from the "Fukushima" NPP constitutes 11-300 Bq m^-2 in the Primorsky Krai, Sakhalin Island and at the Kamchatka peninsula, i.e., 1-22% of the total amount of radionuclides in the soil. The contribution of this radionuclide to the contamination of moss-lichen vegetation ranged from 7 to 42%.

Current assessment of integrated content of long-lived radionuclides in soils of the head part of the East Ural Radioactive Trace

Based on the datasets obtained during investigations from 2003 to 2012, the spatial distributions of (90)Sr, (137)Cs, and (239,240)Pu content in the soils of the head part of the East Ural Radioactive Trace (EURT) were mapped using the geographic information system ArcGIS. Taking into account the presence of spatial autocorrelation and anisotropy in the source data, an ordinary kriging method was applied to interpolate values of radionuclide contamination density at unsampled places. Further geostatistical data analysis was performed to determine the basic parameters of spatial dependencies and to integrally assess the contamination by long-lived radionuclides in soils of the central, east peripheral, and west peripheral parts of the trace. This analysis was based on simplified geometric models (sector- and rectangle-shaped areas). The Monte Carlo method was used to quantitatively assess the uncertainty of the values for the integrated quantities resulting from the statistical errors of the source data approximation.