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It has been suggested that Neandertals, as well as modern humans, may have painted caves. Hoffmann et al. used uranium-thorium dating of carbonate crusts to show that cave paintings from three different sites in Spain must be older than 64,000 years. These paintings are the oldest dated cave paintings in the world. Importantly, they predate the arrival of modern humans in Europe by at least 20,000 years, which suggests that they must be of Neandertal origin. The cave art comprises mainly red and black paintings and includes representations of various animals, linear signs, geometric shapes, hand stencils, and handprints. Thus, Neandertals possessed a much richer symbolic behavior than previously assumed. Science , this issue p. 912 Data from three ancient sites suggest that Neandertals were making cave paintings in Europe more than 64 thousand years ago The extent and nature of symbolic behavior among Neandertals are obscure. Although evidence for Neandertal body ornamentation has been proposed, all cave painting has been attributed to modern humans. Here we present dating results for three sites in Spain that show that cave art emerged in Iberia substantially earlier than previously thought. Uranium-thorium (U-Th) dates on carbonate crusts overlying paintings provide minimum ages for a red linear motif in La Pasiega (Cantabria), a hand stencil in Maltravieso (Extremadura), and red-painted speleothems in Ardales (Andalucía). Collectively, these results show that cave art in Iberia is older than 64.8 thousand years (ka). This cave art is the earliest dated so far and predates, by at least 20 ka, the arrival of modern humans in Europe, which implies Neandertal authorship.

Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full uranium/thorium dating range, that is, the past 640,000 years. The record’s length and temporal precision allow us to test the idea that insolation changes caused by the Earth’s precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record’s timing, the terminations are separated by four or five precession cycles, supporting the idea that the ‘100,000-year’ ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and ‘unfinished terminations’. Records of the Asian monsoon have been extended to 640,000 years ago, and confirm both that the 100,000-year ice age cycle results from integral numbers of precessional cycles and that insolation influences the pacing of major millennial-scale climate events. A 640,000-year record of the Asian monsoon Prior records of the Asian monsoon have revealed cyclic variations over hundreds of thousands of years, probably driven by variations in insolation caused by the precession of Earth's orbit. Hai Cheng and colleagues now provide a speleothem record from Chinese cave samples that extends earlier records to 640,000 years ago, close to the maximum age possible with uranium/thorium dating. This spectacular record confirms that the characteristic '100,000-year' ice age cycle corresponds to an integral number (four or five) of precession cycles, and that insolation influences millennial-scale variations in monsoon strength.

Uranium and thorium are heavy metals, and all of their isotopes are radioactive, so it is impossible to study chemical effects entirely independent of the radiation effects. In the present study, we tried to compare the chemo- and radiotoxicity of both metals, taking into account deterministic radiation damages reflected by acute radiation sickness and stochastic radiation damages leading to long-term health impairments (e.g., tumor induction). We made at first a literature search on acute median lethal doses that may be expected to be caused by chemical effects, as even acute radiation sickness as a manifestation of acute radiotoxicity occurs with latency. By simulations based on the biokinetic models of the International Commission on Radiological Protection and using the Integrated Modules for Bioassay Analysis software, we determined the amounts of uranium at different enrichment grades and thorium-232 leading to a short-term red bone marrow equivalent dose of 3.5 Sv considered to cause 50% lethality in humans. Different intake pathways for incorporation were considered, and values were compared to the mean lethal doses by chemotoxicity. To assess stochastic radiotoxicity, we calculated the uranium and thorium amounts leading to a committed effective dose of 200 mSv that is often considered critical. Mean lethal values for uranium and thorium are in the same order of magnitude so that the data do not give evidence for substantial differences in acute chemical toxicity. When comparing radiotoxicity, the reference units (activity in Bq or weight in g) must always be taken into account. The mean lethal equivalent dose to the red bone marrow of 3.5 Sv is reached by lower activities of thorium compared to uranium in soluble compounds. However, for uranium as well as thorium-232, acute radiation sickness is expected only after incorporation of amounts exceeding the mean lethal doses by chemotoxicity. Thus, acute radiation sickness is not a relevant clinical issue for either metal. Concerning stochastic radiation damages, thorium-232 is more radiotoxic than uranium if incorporating the same activities. Using weight units for comparison show that for soluble compounds, thorium-232 is more radiotoxic than low-enriched uranium in the case of ingestion but even more toxic than high-enriched uranium after inhalation or intravenous administration. For insoluble compounds, the situation differs as the stochastic radiotoxicity of thorium-232 ranges between depleted and natural uranium. For acute effects, the chemotoxicity of uranium, even at high enrichment grades, as well as thorium-232 exceeds deterministic radiotoxicity. Simulations show that thorium-232 is more radiotoxic than uranium expressed in activity units. If the comparison is based on weight units, the rankings depend on the uranium enrichment grades and the route of intake.

This study marks the first-ever assessment of radiological hazards linked to the sands and rocks of Patuartek Sea Beach, situated along one of the world’s longest sea beaches in Cox’ Bazar of Bangladesh. Through the utilization of an HPGe detector, a comprehensive analysis of the activity concentrations of 226 Ra, 232 Th, and 40  K was conducted, and their activity ranged from 7 to 23 Bq/kg, 9–58 Bq/kg, and 172–340 Bq/kg, respectively, in soils, and 19–24 Bq/kg, 27–39 Bq/kg, and 340–410 Bq/kg, respectively, in rocks. Some sand samples exhibited elevated levels of 232 Th, while the rock samples displayed higher levels of 40  K compared to the global average. The radiological hazard parameters were assessed, and no values surpassed the recommended limits set by several international organizations. Hence, the sands and rocks of Patuartek sea beach pose no significant radiological risk to the residents or tourists. The findings of this study provide crucial insights for the development of a radiological baseline map in the country, which is important due to the commissioning of the country’s first nuclear power plant Rooppur Nuclear Power Plant. The data may also stimulate interest in the rare-earth minerals present in the area, which is important for the electronics industry, thorium-based nuclear fuel cycles.

Chemical grafting of low-density polyethylene film blended with ethylene propylene diene monomer rubber (PE/EPDM) using styrene monomer followed by a sulfonation process was investigated. Different factors affecting the grafting process, such as monomer and initiator concentrations, time of reaction, and grafting temperature, were studied. Sulfonation of the grafted films was carried out using chlorosulfonic acid in dichloromethane. Characterization of the grafted and sulfonated films was performed using ATR-FTIR, SEM, TGA, and XRD instruments. The grafting was successfully performed in aqueous media using sodium bisulfite as initiator, reaching a grafting yield of 130% and an ion exchange capacity of 1.2 m eq /g. The removal of thorium ions from aqueous solution was studied using the obtained ion exchange films. The results showed that the maximum adsorption capacity of Th(IV) was 177.5 mg. g −1 (pH = 3, 298 K and 60 min). Removal isotherm and Kinetics were investigated, and the results revealed that the adsorption process was chemisorption homogeneous monolayer adsorption, exothermic, and spontaneous.

Thorium, as an important radioactive element, is widely present in nature, and its accompanying environmental pollution is also serious. Extracellular polymeric substances (EPS) are commonly found on the surface of microbial bodies and have strong adsorption capacity for metal ions. In this study, four methods were used to extract EPS from indigenous bacteria of rare earth tailings and to determine the best extraction method. The extracted EPS was applied to treat Th4+, and the changes in functional groups and composition of EPS were investigated. The results showed that the ultrasonic method was more efficient than other methods. The best removal efficiency was observed at pH 3.5, Th4+ concentration of 20 mg/L, and EPS dosage of 30 mL at 25 °C. After 9 h, the adsorption process reached equilibrium with a maximum removal efficiency of 75.93% and a maximum theoretical adsorption capacity of 25.96 mg/g. The Th4+ removal process was consistent with the Langmuir and Freundlich adsorption isotherms and the kinetic data were consistent with the pseudo-second-order kinetic model, which is mainly based on chemisorption. Amide I and amide II of proteins, C–H from aliphatic, as well as O–H and C = O from carboxylic acid play important roles in the adsorption process.

Antarctic ice-core data reveal that the atmosphere experienced abrupt centennial increases in CO2 concentration during the last deglaciation (∼18 thousand to 11 thousand years ago). Establishing the role of ocean circulation in these changes requires high-resolution, accurately dated marine records. Here, we report radiocarbon data from uranium-thorium–dated deep-sea corals in the Equatorial Atlantic and Drake Passage over the past 25,000 years. Two major deglacial radiocarbon shifts occurred in phase with centennial atmospheric CO2 rises at 14.8 thousand and 11.7 thousand years ago. We interpret these radiocarbon-enriched signals to represent two short-lived (less than 500 years) \"overshoot\" events, with Atlantic meridional overturning stronger than that of the modern era. These results provide compelling evidence for a close coupling of ocean circulation and centennial climate events during the last deglaciation.

This study examines the geological and climatic factors that influence natural radioactivity levels in drinking water from Dessie and Kombolcha towns in Ethiopia’s northern plateau. The basaltic and sedimentary mudrock formations of the region contain high levels of natural radionuclide elevated natural radionuclide levels, while climatic factors such as precipitation, soil moisture, and humidity enhance their mobility and transport into water sources. Kombolcha, situated at a Lower altitude geographically, exhibits higher radionuclide concentrations for 238 U and 232 Th. All measured values are almost greater than the global permissible values 0.5 mBq/L and 0.05 mBq/L respectively, especially for samples collected from running water. This is due to surplus and downward transport along the Borkena River from Dessie to Kombolcha, which is intensified by climatic conditions and rainfall. 40 K shows high activity values in samples from underground and spring water in both towns, even if its global permissible value is clearly not known in ingestion food type. Uranium’s greater solubility compared to thorium results in higher activity levels above 0.5 mBq/L, across both towns in this study. Radiation dose assessments reveal significant health risks, particularly in spring and headwater areas. Annual effective doses exceed the permissible values recommended by international guidelines like IAEA and ICRP in both towns which is 1 mSv/yr. These findings suggest potential long-term health risks, with recommendations for continuous monitoring and mitigation measures to protect public health in the two towns and downstream from the Ethiopian northern plateau.

Following early hypotheses about the possible existence of Arctic ice shelves in the past 1 – 3 , the observation of specific erosional features as deep as 1,000 metres below the current sea level confirmed the presence of a thick layer of ice on the Lomonosov Ridge in the central Arctic Ocean and elsewhere 4 – 6 . Recent modelling studies have addressed how an ice shelf may have built up in glacial periods, covering most of the Arctic Ocean 7 , 8 . So far, however, there is no irrefutable marine-sediment characterization of such an extensive ice shelf in the Arctic, raising doubt about the impact of glacial conditions on the Arctic Ocean. Here we provide evidence for at least two episodes during which the Arctic Ocean and the adjacent Nordic seas were not only covered by an extensive ice shelf, but also filled entirely with fresh water, causing a widespread absence of thorium-230 in marine sediments. We propose that these Arctic freshwater intervals occurred 70,000–62,000 years before present and approximately 150,000–131,000 years before present, corresponding to portions of marine isotope stages 4 and 6. Alternative interpretations of the first occurrence of the calcareous nannofossil Emiliania huxleyi in Arctic sedimentary records would suggest younger ages for the older interval. Our approach explains the unexpected minima in Arctic thorium-230 records 9 that have led to divergent interpretations of sedimentation rates 10 , 11 and hampered their use for dating purposes. About nine million cubic kilometres of fresh water is required to explain our isotopic interpretation, a calculation that we support with estimates of hydrological fluxes and altered boundary conditions. A freshwater mass of this size—stored in oceans, rather than land—suggests that a revision of sea-level reconstructions based on freshwater-sensitive stable oxygen isotopes may be required, and that large masses of fresh water could be delivered to the north Atlantic Ocean on very short timescales. Unexpected intervals of low 230 Th concentration in marine sediment cores are explained by considering that during at least two such periods, the Arctic Ocean and Nordic seas were composed entirely of fresh water and covered by a thick ice shelf.

Soil can pose significant radiation hazard in areas with elevated radioactivity levels from geological or anthropogenic sources, potentially contributing to human exposure through the food chain and atmosphere. However, industrial activities can alter radionuclides distribution by releasing residues or effluents, leading to their accumulation in the environment. In general, soil provides clear insights into geological characteristics and heavy metal exploration, in addition to assessing the risks of radiation exposure. This study investigates the distribution of NORMs and assesses radiological hazards in twenty soil samples collected from two major industrial zones in the Chattogram City of Bangladesh: the Bayazid Industrial Area and the Kalurghat Heavy Industry Area. The activity concentrations of 226 Ra, 232 Th, and 40 K in the analyzed soil samples range from 8 ± 1–18 ± 1, 15 ± 1–35 ± 3, and 192 ± 17–420 ± 35 Bq/kg, respectively, remaining below the global average for soil. The radiological hazard indices indicate negligible health risks to the public or environment, suggesting that the industrial activities are not releasing any radiotoxic elements in the surrounding environment. Statistical analysis identified 40 K and 232 Th as the primary contributors to radiological hazards, supported by strong correlations and significant principal component loadings. Additionally, this study provides baseline data for monitoring environmental radioactivity levels, particularly in light of the upcoming commissioning of the Rooppur Nuclear Power Plant in 2025.