Plutonium, 137Cs and U in some pond and lake sediments from areas surrounding the Semipalatinsk Nuclear Test Site: With emphasis on anomalously high U accumulation

Sediment core samples were collected up to a depth of 25–40 cm from three ponds (P. Korosteli, P. Mihairov and P. Alkat) and two lakes (L. Kanoneruka and L. Semanaika) located in widely separated regions outside the former Semipalatinsk Nuclear Test Site (SNTS) in Kazakhstan. The ¹³⁷Cs, Pu and U concentrations with depth were determined in samples divided at 1 cm intervals from the top of each core. These sediment cores were dated by the excess ²¹⁰Pb method. The reservoirs with low sedimentation rates of 0.038–0.41 g·cm^–2·y^–1 permitted, but not in detail, the estimation of the depositional history of close-in fallout of ¹³⁷Cs and Pu within these regions. The sediments accumulating an anomalously high ²³⁸U concentration of 250–400 Bq/kg were also found for two of the five reservoirs, in which their ²³⁴U/²³⁸U and ²³⁵U/²³⁸U activity ratios were 1.3–2.0 and around 0.047 (nearly the same as that of natural U), respectively. Such U enrichment at the subsurface with a thin layer of lower-U sediment at the surface is mainly due to infiltration of lake water containing U from the ground water flowing into the lake or pond, followed by reduction of U(VI) to U(IV) at the redox boundary.The authors would like to express their gratitude to research staff of the Kazakh Scientific Research Institute for Radiation Medicine and Ecology for sediment and soil sampling. This work was supported by a Grant in Aid for Scientific Research from the Ministry of Education and Culture of Japan, Monbusuo International Scientific Research Program during the period of 1995–2003, represented by Profs. M. Hoshi and M. Yamamoto.     

Plutonium isotopes and 137Cs in Dolon settlement near the Semipalatinsk Nuclear Test Site: About 50 years after the first nuclear weapon testing

Recent controversies concerning the radiation doses for populations living in the village of Dolon due to the nuclear explosions carried out at the Semipalatinsk Nuclear Test Site (SNTS) have encouraged us to evaluate in more detail the levels and distributions of residual long-lived radionuclides¹³⁷Cs and Pu isotopes (²³⁸Pu,^239,240Pu) in soils within the village. Soil core samples up to a depth of about 30 cm and/or 100 cm were collected at 25 sites and subjected to analysis of ¹³⁷Cs and Pu isotopes. The inventories of ¹³⁷Cs and ^239,240Pu were found to be in the wide range of 790-10,310 and 530-14,320 Bq/m², respectively. Sequential leaching of Pu from the soil showed that more than ca. 80% of the ^239,240Pu was not leached by hot digestion with conc. HNO³ + H₂O₂, indicating the presence of Pu associated with fused silicates. Further, the presence of hot-particles from the Pu contaminants by a-track radiography technique using CR-39 polycarbonate was confirmed in the soil, even at present, after about 50 years from the first nuclear weapon testing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Distributions of Pu isotopes and 137Cs in soil from Semipalatinsk Nuclear Test Site detonations throughout southern districts

Soil samples collected mainly from the southern areas, including Kainar and Karaul settlements, around the Semipalatinsk Nuclear Test Site of the former USSR were analyzed for ¹³⁷Cs and Pu isotopes (²³⁸Pu,²³⁹Pu and ²⁴⁰Pu) by γ-ray and α-ray spectrometry and ICP-MS. The ¹³⁷Cs inventories varied widely from 170 to 13,600 Bq/m². The ^239,240Pu inventories, values of which are scare in the literature, also varied in the range of 34-2,050 Bq/m² (most of date being 100-300 Bq/m²). In the areas around Tailan, Sarzal and Karaul settlements where the radioactive cloud related to the first thermonuclear explosion passed through, higher inventories of these nuclides were observed and especially their ²³⁸Pu/^239,240Pu activity ratios (0.0064-0.0076) were markedly lower than those attributed to global fallout (0.03-0.04). The observed ratios might be used as a fingerprint to identify the Pu source of the first thermonuclear event. Most of the ²⁴⁰Pu/²³⁹Pu atomic ratios were lower than those of global fallout (0.18) commonly accepted. The contribution of local fallout ^239,240Pu was higher (more than 80-90%) in the areas around the Tailan, Sarzal and Karaul settlements than that (30-ca. 60%) in the other areas. This high Pu contribution was related to the Pu source from the first thermonuclear event. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pu isotopes and137Cs in the surrounding areas of the former Soviet Union's Semipalatinsk nuclear test site

Field missions were sent to Semipalatinsk City and several settlements near the former Semipalatinsk nuclear test site to investigate the current radioactive contamination levels of the land coming from long-lived radionuclides. The soil was sampled at about 20 sites, including some settlements such as Mostik, Dolon and Chagan, forest and pasture areas, along the roads from Semipalatinsk City to Kurchatov City and to Korosteli settlement in the direction of the Altai District. The radioactivities of¹³⁷Cs,²³⁸Pu and^239,240Pu as well as²⁴⁰Pu/²³⁹Pu atomic ratios in the soil were determined by non-destructive γ-ray spectrometry and radiochemical separation followed by α-ray spectrometry and/or ICP-MS, respectively. The results showed a distinction of¹³⁷Cs and^239,240Pu inventories in soil depending on the site where we visited. While the overall¹³⁷Cs levels were as same as or slightly lower than the domestic global fallout level (3·10³–7·10³ Bq/m²),^239,240Pu levels at some sites were several to a few ten times higher than the domestic level (40–120 Bq/m²). The atomic ratios of²⁴⁰Pu/²³⁹Pu in the soil were in the range of 0.024–0.125, which were significantly lower than the value of 0.18 commonly accepted for global fallout Pu.     

137Cs dating of lake cores from the Nahuel Huapi National Park, Patagonia, Argentina: Historical records and profile measurements

Historical records of short lived (¹⁴⁰Ba, ¹³¹I, ¹⁰³Ru and ⁹⁵Zr+⁹⁵Nb) and long-lived (¹³⁷Cs and ⁹⁰Sr) fission products by fallout measurements performed in Argentina since 1959 were analyzed in order to define the main characteristics of ¹³⁷Cs fallout time evolution in the Nahuel Huapi National Park, Patagonia, Argentina. Sedimentary cores were sampled from Lake Nahuel Huapi and Lake Morenito, which are located within Nahuel Huapi National Park. ¹³⁷Cs specific activity profiles were measured and ²¹⁰Pb dating was performed in each core. The time evolution of ¹³⁷Cs fallout shows different characteristics than records taken in the Northern Hemisphere.¹³⁷Cs specific activity profiles of the cores studied reproduce the fallout time sequence observed in the historical records, and the chronology obtained shows excellent agreement with ²¹⁰Pb dating.     

Current levels and distribution of 137Cs and Pu isotopes in soil on the Kazakhstan territory of the Kazakhstan-Chinese border: Semipalatinsk and Lob Nor nuclear test sites detonation

More than 100 soil samples were collected from 46 sites along roads and some settlements connecting Alma-Ata to Semipalatinsk City of the Kazakhstan-Chinese border and analyzed for ¹³⁷Cs and Pu isotopes (²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu). The mean ¹³⁷Cs inventory at each site was within the range of 1,000-3,000 Bq/m² for most of the sites. The ^239,240Pu concentration and its inventories were observed in the wide range of 0.18-2.6 Bq/kg and 28-677 Bq/m², respectively. At the most northern sites in the areas studied, higher^239,240Pu inventories were found corresponding to the increase of ^239,240Pu fraction which was not leached by hot digestion with conc. HNO₃+H₂O₂. The ^239,240Pu/¹³⁷Cs activity ratios for the soil samples from the southern areas lie in the narrow range of 0.016–0.039 (most of data being 0.02–0.03), probably indicative of global fallout origin. On the other hand, a little or several higher ratios (0.05 to 0.22) were found for soil samples from the northern areas. These higher ratios demonstrate strongly that there was additional Pu input of local fallout due to the atomic explosions. From ²⁴⁰Pu/²³⁹Pu atomic ratios measured, contribution of local fallout ^239,240Pu, probably from the SNTS, was found to be higher (60–86%) in the sites around the northern areas than the southern ones. The present data might serve not only as a current baseline information on distribution and contamination levels of the long-lived fallout radionuclides in the Kazakhstan areas of the Kazakhstan-Chinese border, but also as a aid of selection of control area for epidemiological projects.     

239Pu, 240Pu, 241Pu, 241Am, 137Cs,and 210Pb in seafloor sediments in the western North Pacific Ocean and the Sea of Japan: distributions,sources and budgets

Journal of Radioanalytical and Nuclear Chemistry - Vertical distributions of 239Pu, 240Pu, 241Pu, 241Am, 137Cs, and 210Pb concentrations, and 240Pu/239Pu ratios were determined in seafloor...     

A study on the activity concentrations of 226Ra, 232Th, 40K, 137Cs and radiological risk assessments in soil samples from Seydisehir and Beysehir districts of Konya in Turkey

Journal of Radioanalytical and Nuclear Chemistry - The aim of this study is to investigate the activity concentrations of 226Ra, 232Th, 40K and 137Cs in soil samples from Seydisehir and Beysehir...