Distribution Of Thorium Research Articles

230Th/U burial dating of ostrich eggshell

Obtaining precise and accurate dates for late Quaternary terrestrial sequences containing Middle Stone Age or Middle Paleolithic archaeological materials (ca. 30–300 ka) can be challenging. Many such sequences lie beyond the limit of radiocarbon dating (∼50 ka) and lack volcanic ashes suitable for 40Ar/39Ar dating. We report a dating approach with about ten times the range of radiocarbon dating (∼500 ka) based on a novel protocol for 230Th/U dating of ostrich eggshell, a common component of African, Near Eastern and Asian archaeological sequences. Uranium in ostrich eggshell, typically at levels of tens to hundreds of ppb, is acquired after burial. However, accurate burial ages can be determined from measured 230Th/U ages when corrected for uranium uptake via diffusion. Using ostrich eggshells from a Pleistocene-Holocene east African site, we have: (1) characterized the spatial distribution of uranium and common thorium (232Th) concentrations in ostrich eggshell by laser ablation ICP-MS, (2) determined apparent 230Th/U ages on outer and inner layers of eggshells by solution ICP-MS analyses of selectively abraded eggshells, and (3) calculated 230Th/U burial ages using a simple model for diffusive uptake of uranium. We assess our method by comparing the 230Th/U burial ages (median uncertainty 2.3%, 1 SD) with radiocarbon dates on carbonate from the same eggshells. We find good agreement in seven out of nine eggshells, confirming the accuracy of their 230Th/U model ages. Eggshells that fail to yield reliable 230Th/U ages may be recognized by anomalous patterns of apparent 230Th/U ages, providing a reliability criterion innate to the 230Th/U data. Ostrich eggshells are resistant to diagenesis simplifying 230Th/U dating compared to bones and teeth. Eggshells of ostrich, emu, rhea and other living and extinct ratites found on six continents share similar structure and composition, suggesting our new approach to 230Th/U dating of eggshell may be applicable in diverse late Quaternary terrestrial settings.

Thorium distribution on the Moon: new insights from Chang’E-2 gamma-ray spectrometer**A contributed paper from the International Symposium on Lunar and Planetary Science (ISLPS) held on 2018 June 12–15 at Macau University of Science and Technology.

We present the thorium distribution on the lunar surface derived from observations by the Chang’E-2 gamma-ray spectrometer (CE-2 GRS). This new map shows a similar thorium distribution to previous observations. In combination with this new thorium map and impact cratering model, we investigate the origination of thorium on the Moon’s highlands, which was previously thought to be contributed from Imbrium ejecta. We found that the Imbrium ejecta has a small contribution (∼20%–30%) to the thorium on the lunar highlands but most thorium is likely to be indigenous before the deposition of the Imbrium ejecta. This new thorium map also confirms that the eastern highlands have a relatively higher thorium concentration than the western highlands. We propose that the thin crust and large basins on the eastern highlands are responsible for this difference in thorium.

GEOTECHNICAL AND RADIOMETRIC STUDIES FOR EL-HAMRAWEIN AREA- EASTERN DESERT- EGYPT

This research involves geotechnical and radiometric studies for El-Hamrawein area- Eastern Desert- Egypt. The studied area is mainly composed of gravely sands enriched soil cover the rock with large thickness. Laboratory tests were performed on representative soil and rock samples to determine their physical, mechanical and chemical characteristics such as: grain size distribution, specific gravity, moisture content, bulk density, shear box, bearing capacity, unconfined compressive strength, chemical analysis, uranium and thorium concentrations of rocks and soils. One hundred and eight samples were collected from 16 boreholes and classified into 24 rock sample and 84 friable sand and gravel, have been taken at a depth from 1 to 15 m. Uniformity coefficient (Cu) value ranges from (4.55mm) to (7.91mm) and curvature coefficient (Cc) value ranges from (1.98mm) to (0.70mm). The studied samples in this study are classified as well-graded soil from the point of view of classification engineering geology. Specific gravity values range from 2.47 to 2.70. The geotechnical studies include direct shear test, where effective friction angle (ϕ) range from 36o to 37o and bearing capacity of soil are ranging from (1901 KN/m2 to 2059 KN/m2). Radiometric studies including gammaray logging and quantitative uranium and thorium analyses were carried out in order to give an idea about the distribution of uranium and thorium in the study area. Uranium ranges from 1.8ppm to 2ppm, thorium range from 3.6ppm to 4.2ppm at different depths from 0 to 5m. These values indicate that the area has safe radiation .

Activity concentrations of radionuclides in soil samples along the coastal areas of Kerala, India and the assessment of radiation hazard indices

The present study was carried out along the coastal regions of Kerala, India, to evaluate the distribution of uranium, thorium and potassium concentrations in surface soil samples. A total of 92 soil samples were collected from 9 coastal districts, lying by the side of the Arabian Sea. The radium equivalent activities in the beach sands of Kollam district varies from 877 to 3715 Bq kg−1, which is higher than the reference limit of 370 Bq kg−1. Results show that the radiological parameters obtained for the beach sand from the districts of Thiruvananthapuram, Alapuzha, Eranakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod are within the safe limits and hence these places can be considered as Normal Background Radiation Areas. Thus, when the high radioactive places are confined to a narrow belt in Kollam district, the other coastal areas of Kerala, especially northern and middle zones are within the safe limit with respect to radiological index.

Enhancing the Radiometric Map of Australia

The Radiometric Map of Australia shows the distribution of potassium (% K), uranium (ppm eU) and thorium (ppm eTh) over Australia. A suite of image enhancement and data integration techniques can be used to enhance the value of these data for both mineral exploration and environmental mapping. Gradient-enhanced ternary and pseudo-colour image enhancements are now routinely used for the presentation and interpretation of gridded radioelement data. Where digital elevation data are available, these colour representations can be draped over the elevation data to form 3D perspective views, or hill-shaded derivatives of the DEM can be embedded into the ternary imagery as an intensity component. These are useful because the radioelement response can then be interpreted within the context of the relative position of anomalous features in the landscape. However, subtle variations in the concentrations of K, U, and Th are best interpreted using the ratios of the radioelements. The U/Th and U2/Th ratios are important indicators of uranium mineralization. The Th/K ratio is widely used for the detection of several styles of mineralization associated with K alteration. For the interpretation of map data, classification and clustering methods can be used to assist pattern recognition and are useful for the rapid assessment of large multivariate datasets. Automatic edge detection procedures can be used to speed up the annotation of unit boundaries. Residual modelling techniques can be used to highlight potential anomalies in the data.

Thorium and Uranium distribution in a passive system for mine water treatment

The abandoned Jales mining area is a sulphide-rich deposit (Northeast of Portugal). Acid mine drainage resulted from oxidation of sulphides is treated in a passive system with wetlands. The present work studies the thorium and uranium behaviour in the water and in the fine fractions of wetland soils throughout the passive treatment system. The evaluation of the efficiency of the all system was done determining metals concentration variation in the creek water upstream and downstream of the treated effluent discharge. The results point to higher efficiency to retain Th after summer than after winter. The opposite was found for uranium, which increases significantly in the creek water after summer and, in a lower extent, after winter. Also, Th and U have a tendency to increase in the fine fractions of the wetlands soils after summer, which can be explained by the longer water-soil contact/lower water dynamics. Nevertheless uranium has a much higher tendency to be in solution as revealed by a high concentration in the porewater of wetland soils. A relation of these actinides behaviour with the Fe and Mn distribution is not clear.

Thorium Harmful Impacts on the Physiological Parameters of the Adult Male Albino Rats and Their Mitigation Using the Alginate

Thorium-232 is a natural radionuclide from the actinide family, is abundantly present in monazite and other ores after thorium occupational or accidental exposures it deposited in many organs. The object of the study is to investigate thorium shortterm hazards effects on the male albino rate and study the alginate mitigation effect on thorium hazards. Rats were grouped into control, Thorium (Th) and Th+Alginate(Alg) groups. The 54 rats of the different groups were decapitated (6 rats for each decapitation) after the 1st, 3rd, and 7th day during the treatment. Parameters of hematological (Hb, RBCs, indices, granular, lymphocytes), liver (GOT, GPT, Alb.), lipid (chol., trig.) kidney (creat., urea, uric acid) were determined after the determination of thorium distribution and accumulation in different organs. The results showed that the IP administration of 13.6 mg/kg b.wt. thorium nitrate (Th) for seven days produced an organs distribution of Th and accumulated in liver>brain>lipid>Kidney>heart>testes at the end of the experiment, also it induced a hematological, hepatic and lipid dysfunction with no effect on renal function. On the other hand, the oral administration of 5% alginate in the drinking water in parallel with Th injection could slightly reduce Th hazardous effects which may be due to alginate ability to inhibit many inflammatory factors that reduce the hemolysis in erythrocyte, reduce hepatocellular apoptosis, enhance the cholesterol excretion into the feces and also due to the antioxidant and chelating capacity of alginate to Th ions. So, alginate administration could ameliorate Th short-term hazards effects.

Environmental radioactivity studies in Kabul and northern Afghanistan

From earlier surveys conducted by soviet researchers, the Kabul area was identified as a region of high natural radioactivity. In addition, depleted uranium ammunition was used by the Soviet armed forces. Fragmentary maps (often only given in relative units) indicate regions of anomalously elevated gamma radiation dose rates. In recent years, residential houses have been built in some of these places. However, no detailed information of uranium and thorium distributions in the upper soil and rock exists. In order to assess possible radiological risk, soil and rock samples as well as all-purpose water samples were collected and measured with regard to radioisotope content and contamination by other pollutants such as, e.g., heavy metals. Activity concentrations in soil and rocks ranged between 160 to 28,600 Bq/kg, 73 to 383,000 Bq/kg, and 270 to 24,600 Bq/kg for uranium, thorium, and potassium, respectively. The elevated thorium abundances was traced back to incorporation into cheralite minerals. No anomalies of the radioactive equilibria were found in the decay chains. Hence, contributions of depleted uranium or other anthropogenic sources can be excluded. However, the high uranium content causes enhanced radon levels in houses and dwellings up to mean activity concentrations of 2000 Bq/m3 strongly exceeding the reference level of 300 Bq/m3 recommended by the ICRP. Heavy metal concentrations of some of the investigated waters also exceed the regulatory limits and are not safe for drinking. Dose assessments are given.

Thorium distribution in the crust: Outcrop and grain-scale perspectives

The spatial distribution of heat producing elements (K, U, and Th) in the continental crust has long-term implications for the thermal and physical evolution of orogens. Heat producing elements, in particular Th, are most abundant in metasedimentary rock types. As such, these rock types have a significant control on the spatial distribution of heat production in the crust. The major host of the heat producing element thorium in pelitic metasedimentary rocks is the REE–Th phosphate monazite. We present in-field gamma ray spectrometry (in-field GRS) data integrated with grain-scale electron probe microanalysis data to reveal grain to terrane scale links in thorium distribution. In-field GRS data shows that thorium is not depleted in granulite facies residual rocks that have lost melt with respect to their subsolidus counterparts. Concurrently, the bulk thorium budget of monazite is approximately uniform within samples and if anything increases with increasing metamorphic grade. Monazite average grain size increases with metamorphic grade and prograde cores are largely preserved in granulite facies samples. Thorium is preserved in residual metasediments after melting and melt loss implying that even when melting and melt extraction is efficient it does not strip Th from granulite facies rocks.

Natural radioactivity levels in sediments in Algiers Bay using instrumental neutron activation analysis

Abstract The main objective of this study is to evaluate natural radioactivity levels in sediments collected from different points of Algiers bay. Particular attention was paid to understand correlations between the distribution of uranium and thorium and the geomorphological characteristics of the Bay. Instrumental neutron activation analysis (INAA) has been employed in order to measure the isotopic composition and concentration of uranium and thorium, with emphasis on isotopes, 232Th and 238U. The concentrations reported in Bq kg−1 (dry weight) vary between 19.73 and 34.53 for 238U and between 22.26 and 36.02 for 232Th. The obtained results are within the world typical ranges and did not show any anomalous values. Results revealed clear inverse relationship between activity concentration and grain size. The radioactivity content in sediments had a positive correlation with clay and silt percentage, and a negative correlation with sand percentage. The concentration ratios of 232Th/238U are found to be slightly below the world average value unite (3.94) in sediments. Values below unite indicate that the medium is reductor or the existence of an external source of U-contaminated particles in the bay; Values greater than the unit show either depletion of uranium or enrichment of thorium due to alteration or natural processes in these areas. The strong correlation of uranium and Thorium in samples reflects the source of same origin. The results of the study can be used as basic radiometric data for future sedimentological studies. The situation in the Bay of Algiers is reassuring but the risk of possible contamination cannot be excluded and requires constant vigilance for the preservation of the coast and the Mediterranean from all contamination. The results can also be used as reference data for the monitoring of possible radioactive pollution in the future.

Geochemistry of Thorium and Uranium in Soils of the Southern Urals

Specific features of the horizontal and vertical distribution of uranium and thorium in soils and parent materials of the Southern Urals within the Bashkortostan Republic have been studied with the use of mass spectrometry with inductively coupled plasma. The dependence of distribution patterns of these elements on the local environmental conditions is shown. A scale for soil evaluation according to the concentrations of uranium and thorium (mg/kg) is suggested: the low level, up to 3; medium, up to 9; high, up to 15; and very high, above 15 mg/kg. On the basis of to this scale, the ecological state of the soils is evaluated, and the schematic geochemical map of the region is compiled. The territory of Bashkortostan is subdivided into two parts according to the contents of radioactive elements in soils: the western part with distinct accumulation of uranium and the eastern part with predominant thorium accumulation. This finding supports the charriage (thrust fault) nature of the fault zone of the Southern Urals. The vertical distribution patterns of uranium and thorium in soils of the region are of the same character. The dependence between the contents of these two elements and rare-earth elements has been established. The results of this study are applied for assessing the ecological state of soils in the region.

Identifying the source of natural gamma-rays in shallow-marine siliciclastic strata and their significance for shale evaluation: A case study of the CO2 storage aquifer at the Nagaoka site, Japan

Gamma-ray (GR) logging measures naturally occurring gamma radiation in strata, and is a widely used method for reservoir characterization. The objectives of this study are to identify the source of total GR, and to discuss criteria for reasonable shale evaluation by the combined use of sediment core and GR logging analysis using a case study of the CO2 storage aquifer at the Nagaoka site in Japan. The aquifer is comprised of shallow-marine siliciclastic deltaic deposits characterized by prodelta to delta front facies. The profile of total GR output is consistent with that of mud content, suggesting that the main source of GR can be attributed to minerals in the mud fraction. Prior to comparison of the radioactive elements measured by spectral gamma-ray (SGR) logging and elements from core analysis with total GR, elements were transformed to centered log-ratios to remove constant-sum constraints. Evaluation of the total GR profile with radioactive elements from SGR logging indicates that the distribution of thorium (Th) exhibits a high contrast between prodelta and delta front deposits. Th content has a significant positive correlation with total GR, implying that Th-bearing minerals mostly appear in fine-grained fraction. Conversely, the distribution of potassium (K) has a significant negative correlation with total GR, implying that K-bearing minerals appear in coarse-grained fraction. Based on geochemical analysis of the sediment core, minerals composed of Mg, Ti, Fe, Zr, and Th are likely to be radioactive carriers in the fine-grained fraction, and those containing Na, Al, Si, K, Rb, and Sr are considered to be the radioactive carriers in the coarse-grained fraction. The former can be attributed to detrital zircon grains and clay minerals, including smectite and chlorite, which contain or adsorb the radioactive Th, and the latter can be attributed to K-feldspar. The dispersion diagram between total GR and radioactive elements at observation wells emphasizes the differences in the endmembers of total GR between the two depositional sequences. The estimated shale volume is concordant with measured values if we select the endmembers at each depositional sequence. This means that the endmembers should be selected independently for each depositional sequence to enhance the reliability of shale evaluation. For improving shale evaluation, the combined use of GR logging and detailed core analysis in terms of sedimentology and geochemistry appears to be effective for reliably assessing shale volume in the target strata.

Distribution of uranium in sediment of creek ecosystem

The present study was carried on distribution of uranium isotopes and Thorium in marine sediment from creek of Mumbai Harbour Bay (MHB) using radiochemical separation followed by alpha spectrometry. The activity concentration of uranium and thorium in sediment of MHB has ranged between 1–4 and 1.8–4.5 ppm respectively. The activity ratio of 234U/238U in sediment was found close to unity at most of the locations of creek suggesting a conservative behaviour. The observed Th/U ratio (0.9) in comparison to global Th/U ratio (≅3.5) in the creek sediment indicates that it receives low radiogenic nature of terronenous input.

Thorium distributions in high‐ and low‐dust regions and the significance for iron supply

AbstractThorium and uranium isotopes (232Th, 230Th, 238U, and 234U) were investigated to refine their use for estimating mineral dust deposition and Fe delivery to the ocean. U concentrations and isotope ratios were consistent with conservative behavior and can safely be described using published U‐salinity relationships and global average seawater isotopic composition. Near Barbados, waters affected by the Amazon outflow contained elevated 232Th. This signals one region where the thorium‐dust method is inaccurate because of a confounding continental input. Dissolved 232Th fluxes in this region suggest that Amazonian Fe supply to the adjacent open ocean is much larger than local atmospheric deposition. The colloidal content of dissolved Th south of Bermuda was found to be quite small (2–6%), similar to that found north of Hawaii, despite the order of magnitude higher dust deposition in the Atlantic. This finding supports the assumption that dissolved 232Th and 230Th are scavenged at the same rate despite their different sources and also sheds light on the increase of dissolved 232Th fluxes with integrated depth. Outside the region influenced by Amazon River waters, dissolved 232Th fluxes are compared with Bermudan aerosol Fe deposition to estimate that fractional Th solubility is around 20% in this region. Finally, new dissolved and soluble Fe, Mn, and Cr data from the subtropical North Pacific support the idea that Fe concentrations in the remote ocean are highly buffered, whereas 232Th has a larger dynamic range between high‐ and low‐dust regions.

Distribution of rare earth elements, thorium and uranium in streams and aquatic mosses of Central Portugal

The distribution of 14 rare earth elements, Th and U was studied in streams of the study area at 21 sites. Aquatic mosses are known to accumulate even metabolically nonessential or toxic metals in concentrations much higher than their aqueous environment due to their unique morphology and physiology. Thus, the capacity of metal amplification in four aquatic mosses (Fontinalis squamosa, Brachythecium rivulare, Platyhypnidium riparioides and Thamnobryum alopecurum) was also evaluated as a potential bioindicator/biomonitoring tool. Thirteen REEs (0.001–2.81 μg L−1) and U were detected in the stream water. Mean content of lighter rare earth elements (LREEs) was higher than that of heavier rare earth elements (HREEs). Fourteen REEs and two actinides were detected in moss samples, including Yb and Th which were below detection level in water samples. LREE uptake (0.17–12.2 mg kg−1) was greater than HREE uptake (0.02–0.78 mg kg−1) in all mosses. Uptake of LREEs was observed in the order: B. rivulare >T. alopecurum >F. squamosa >P. riparioides and that of HREEs in the order: T. alopecurum >B. rivulare >F. squamosa >P. riparioides. Mean U content (0.68–1.62 mg kg−1) in the mosses was found in the order: B. rivulare >F. squamosa >T. alopecurum >P. riparioides. Th content ranged from 0.4 to 2.36 mg kg−1 in the order: B. rivulare >T. alopecurum >P. riparioides >F. squamosa. One-way ANOVA indicated a statistically significant difference (P ≤ 0.01) in mean concentrations of all elements (individually) in moss samples except for U. Highest bioconcentration factors of six REEs each were observed in B. rivulare (La, Ce, Sm, Eu, Tb and Dy) and T. alopecurum (Nd, Gd, Ho, Er, Tm and Lu). The highest BCFs for Pr and U were obtained in F. squamosa and P. riparioides, respectively. These species hold promise for biomonitoring studies in the future.

Распределение урана и тория в почве и растениях Восточной Сибири (Иркутская область)

Распределение урана и тория в почве и растениях Восточной Сибири (Иркутская область)

REE, Uranium (U) and Thorium (Th) contents in Betula pendula leaf growing around Komsomolsk gold concentration plant tailing (Kemerovo region, Western Siberia, Russia)

The article deals with the research findings of peculiarities of REE, Uranium and Thorium distribution in the territory surrounding the tailing of former Komsomolsk gold concentration plant according to the data from Betula pendula leaf testing. In the leaf element composition the slight deficiency of MREE and substantial excess of HREE are presented. In the nearest impacted area around the tailing, La, Yb, U and Th content, and Th/U ratio are lower than in the distant buffer area. It is shown, that value of Th/U ratio and REE can be an indicator for geochemical transformations of technogenic landscapes in mining districts. The results of the research can be used for biomonitoring of the territory around the tailing.

Preliminary results of spatial distribution of uranium and thorium in soil profiles near a uranium industrial site, Guangdong province, China

Abstract Four soil profiles were collected from locations with different distances (5, 50, 250 and 1000 m) from a uranium mill tailings dam, Guangdong province, China, to investigate the pollution status of the soil in mining/milling-related areas based on the contents of uranium (U) and thorium (Th), thus to understand the impacts of uranium industrial activities to the surroundings. The U and Th concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) after conventional HF-HNO3-HClO4 digestion procedures. The results indicate that the soils within 50 m from uranium tailing were severely contaminated; those in 250 and 1000 m soil samples were observed to be with local background level even though these in 250 m had slightly higher U/Th ratios. Uranium concentrations varied from 5.50 ± 0.27 to 160.55 ± 8.03 mg/kg, with maximum values recorded in an intermediate layer of the 5-m distance soil profile. In comparison, the concentration of Th ranged from 6.02 ± 0.30 to 84.71 ± 4.24 mg/kg, with maximum values observed in the top layer of the 1000-m distance soil profile. The U/Th ratio varied from 0.15 to 11.99 compared with 0.20, 0.22 and 0.26 of the average for Guangdong province, national China and the world, respectively. The mean U/Th of four soil profiles showed a reduction with distance from the uranium mill tailing dam, suggesting the relatively large magnitude of uranium elevation in soils within limited distances.

Features of distribution of uranium and thorium in red mud

Features of distribution of uranium and thorium in red mud

Thorium distribution in the soils of Peninsular Malaysia and its implications for Th resource estimation

As the national electricity consumption peaked over the years, and the reserves of fossil fuels are becoming scarce, interest in thorium fuel-based nuclear energy generation as an alternative energy source for Malaysia is renewed. This paper provides a preliminary investigation of thorium (Th) availability in Peninsular Malaysia. The study is based on assessment of Th contents in soil. Indicated by massive and fertile Th resources associated with granitic belts, 4 series of regional on-ground explorations are implemented in Peninsular Malaysia to obtain the baseline data of Th availability. The geological settings of Th prospect areas and the result of statistical analyses of Th data are discussed. The isoconcentration mapping of Th is developed and the Th prospect areas in Peninsular Malaysia are highlighted. The possibility, availability, production trends and economic issues of Th recovery from tin by-products and heavy mineral products, as well as the potential of black sand placer deposit as a Th resource in Peninsular Malaysia are also discussed.