This article investigated the kinetic studies of thorium adsorption from an aqueous solution with graphene oxide functionalized with aminomethyl phosphonic acid (AMPA) as an adsorbent. First, the AMPA-GO adsorbent was characterized using TEM, XRD, and FTIR methods. Experiments were performed in two batch and continuous modes. In batch mode, adsorption kinetics were studied in different pH (1-4), temperature (298-328 K), initial concentration (50-500 mg L-1), and dosages (0.1-2 g L-1). The results showed that thorium adsorption kinetic follows pseudo-first-order kinetic model and that the adsorption reaction is endothermic. The maximum experimental adsorption capacity of thorium ions was observed 138.84 mg g-1 at a pH of 3, adsorbent dosage of 0.5 g L-1, and a temperature of 328 K. The results showed that AMPA-GO adsorbent can be used seven times with an acceptable change in adsorption capacity. In continuous conditions, the effect of feed flow rate (2-8 mL min-1), initial concentration (50-500 mg L-1), and column bed height (2-8 cm) was investigated. The continuous data was analyzed using the Thomas, Yoon-Nelson, and Bohart-Adams models. The experimental data of the column were well matched with the Thomas, and Yoon-Nelson models. The research results showed that the use of functionalized graphene oxide adsorbents has a great ability to remove thorium from aqueous solutions.

Coastal Mangroves are facing growing threats due to the harmful consequences of human activities. This first-ever detailed study of natural radioactivity in soil samples collected from seven tourist destinations within the Sundarbans, the world\'s largest mangrove forest, was conducted using HPGe gamma-ray spectrometry. Although the activity levels of 226Ra (11 ± 1-44 ± 4 Bq/kg) and 232Th (13 ± 1-68 ± 6 Bq/kg) generally align with global averages, the concentration of 40K (250 ± 20-630 ± 55 Bq/kg) was observed to surpass the worldwide average primarily due to factors like salinity intrusion, fertilizer application, agricultural runoff, which suggests the potential existence of potassium-rich mineral resources near the study sites. The assessment of the hazard parameters indicates that the majority of these parameters are within the recommended limits. The soil samples do not pose a significant radiological risk to the nearby population. The results of this study can establish important radiological baseline data before the Rooppur Nuclear Power Plant begins operating in Bangladesh.

This work aimed to support Albania\'s food safety monitoring regime. In this context, the natural and artificial radioactivity was measured in 20 samples of dried fruits collected randomly in different markets of Tirana. The activity concentration of 40K, 226Ra, 232Th and 137Cs was determined by using the high-purity germanium detector. The maximum values of activity concentration in dried fruits were calculated as 517 ± 22 Bq kg-1 for 40K, 11.10 ± 0.93 Bq kg-1 for 226Ra, 4.38 ± 0.26 Bq kg-1 for 232Th and 0.83 ± 0.14 Bq kg-1 for 137Cs. The average values of activity concentration of 40K and 226Ra were 269and 6.05 Bq kg-1 and the average effective dose to individuals from the intake of the dried fruits was 44 μSv y-1. All average values in this study were lower than recommended values by reports United Nations Scientific Committee on the Effect of Atomic Radiation, World Health Organization and International Commission on Radiological Protection for all age groups. Therefore, all dried fruit samples in this study are safe for consumption with acceptable radiological risk and none of them pose any significant radiological impact. The obtained data in this paper and information for levels of radioactivity and ingestion absorbed dose from dried fruits can be used to be the basic data for future comparative analysis of the other studies.

The most effective approach to mitigate the toxic effects of internal exposure of radiometals to humans is metal-ligand (ML) chelation therapy. Thorium (Th)-induced carcinogenesis as well as other health hazards to humans as a result of chronic internal exposure necessitates the development of efficient Th-decorporating agents. In this regard, chemical and biological studies were carried out to evaluate N-(2-Acetamido)iminodiacetic acid (ADA), a comparatively cost-effective, readily available, and biologically safe complexing agent for Th decorporation. In the present work, detailed thermodynamic studies for complexation of ADA with Th(IV) have been carried out to understand Th-ADA interaction, using potentiometry, calorimetry, electrospray ionization mass spectrometry, and theoretical studies, followed by its biological assessment for Th decorporation. Thermodynamic studies revealed the formation of strong Th-ADA complexes, which are enthalpically as well as entropically favored. Interestingly, density functional theory calculations, to obtain a thermodynamically favored mode of coordination, showed the uncommon trend of lower denticity of ADA in ML than in ML2, which has been explained on the basis of stabilization of ML by hydrogen bonding. The same was also reflected in the unusual trend of enthalpy for Th-ADA complexes. Biological experiments using human erythrocytes, whole human blood, and lung cells showed good cytocompatibility and ability of ADA to significantly prevent Th-induced hemolysis. Th removal of ADA from erythrocytes, human blood, and normal lung cells was found to be comparable with that of diethylenetriamine pentaacetate (DTPA), an FDA approved decorporating agent. The present study contributed significant data about Th complexation chemistry of ADA and its Th decorporation efficacy from human erythrocytes, blood, and lung cells.

The main purpose of this study was to determine the natural radioactivity level of raw radionuclides in the metal tailings of a mine in Lhasa, Tibet, and to conduct sampling and detection in 17 typical metal tailing mines in Lhasa, Tibet. The specific activity concentrations of 226Ra, 232Th, and 40K in the samples were calculated. The total αβχγ radiation, radon concentration, and outdoor absorbed dose rate in the air 1.0 m above the ground were measured. The γ radiation levels affecting miners and their surrounding residents were assessed. The results show that the radiation dose ranges from 0.08 μSv/h to 0.26 μSv/h, and the radon concentration ranges from 10.8 Bq/m3 to 29.6 Bq/m3, which does not exceed the national radiation-related standards, and the environmental hazard risk is low. The specific activity concentration of 226Ra ranged from 8.91 Bq/kg to 94.61 Bq/kg, the specific activity concentration of 232Th ranged from 2.90 Bq/kg to 89.62 Bq/kg, and the specific activity concentration of 40K was less than MDA to 762.89 Bq/kg. The average absorbed dose rate (DO) of the 17 mining areas was 39.82 nGy/h, the average annual effective dose rate (EO) was 0.057 mSv/y. The average external risk index of the 17 mining areas was 0.24, the average internal risk index was 0.34, and the average γ index was 0.31, all of which were less than the maximum permissible limit. This means that the metal tailings from all 17 mining areas were within the limit for γ radiation and, therefore, can be used in bulk as major building materials without posing a significant radiation threat to the residents of the study area.

The Steenkampskraal mine in the Western Cape Province in South Africa provides some interesting challenges for radiation protection practitioners in view of the high thoron values encountered in this mine. The mine contains high natural thorium concentrations that lead to high thoron activity concentrations, as will be shown in this paper. The influence of ventilation has been studied, and the source term has been investigated by considering the thorium content of the rocks and the thoron exhalation. The thoron activity concentrations are around 10 kBq m -3 at a monazite seam, and the thorium exhalation is consistent with these levels. The thoron concentrations can be reduced by ventilation but not eliminated. However, the thoron progeny can probably be reduced dramatically. Issues that affect the thoron levels are also discussed. Further studies are needed, but the thoron may well not be a radiation protection problem despite the high thoron concentrations.

The surface morphology and chemical states of W-2%ThO2 thermionic cathode during vacuum high-temperature treatment were investigated in this research. The W-2%ThO2 thermionic cathode was prepared by a solid-liquid doping method combined with high-temperature sintering. The morphology and distribution of thorium oxide were observed using a transmission electron microscope and scanning electron microscope. The chemical states of elements at different temperatures were analyzed by X-ray photoelectron spectroscopy. Results indicate that the surface morphology and chemical form of the alloy evolve with the increase of temperature. The matrix had a lamellar structure at low temperatures, and the surface was relatively flat. The samples were heated to 500 °C, 1100 °C, and 1300 °C for 1 h. During the heating process, thorium oxide changed from granular to spherical, and the matrix was recrystallized. As the heating temperature rises, diffusion channels appear inside the cathode. As the temperature increases, the high-priced tungsten gradually decreases, and the zero-valent tungsten content increases. The adsorbed oxygen left the cathode surface, and the lattice oxygen increased. The surface oxygen content decreased, and the thorium and tungsten content increased.

This study aimed to evaluate the radiological hazards of uranium (238U), thorium (232Th), and potassium (40K) in microgranitic rocks from the southeastern part of Wadi Baroud, a northeastern desert of Egypt. The activity concentrations of the measured radionuclides were determined by using a gamma-ray spectrometer (NaI-Tl-activated detector). The mean (238U), (232Th), and (40K) concentrations in the studied rocks were found to be 3680.3, 3635.2, and 822.76 Bq/kg, respectively. The contents in these rocks were elevated, reaching up to 6.3 wt%. This indicated the alkaline nature of these rocks. The high ratios of Th/U in the mineralized rocks could be related to late magmatic mineralization, suggesting the ascent of late magmatic fluids through weak planes such as faults and the contact of these rocks with older granites. The present data were higher than those of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) guideline limits. All the radiological hazard results indicated high human health risks. This confirmed that this area is not radiologically safe, and care must be taken when working in this area. This study showed that the area under investigation had high U content suitable for uranium extraction that could be used in the nuclear fuel cycle.

Thorium is one of the most widespread radioactive elements in natural ecosystems, along with uranium, it is the most important source of nuclear energy. However, the effects of thorium on living organisms have not been thoroughly studied. Marine luminescent bacteria and their enzymes are optimal bioassays for studying low-dose thorium exposures. Luminescent bioassays provide a quantitative measure of toxicity and are characterized by high rates, sensitivity, and simplicity. It is known that the metabolic activity of bacteria is associated with the production of reactive oxygen species (ROS). We studied the effects of thorium-232 (10-11-10-3 M) on Photobacterium phosphoreum and bacterial enzymatic reactions; kinetics of bacterial bioluminescence and ROS content were investigated in both systems. Bioluminescence activation was revealed under low-dose exposures (<0.1 Gy) and discussed in terms of \"radiation hormesis\". The activation was accompanied by an intensification of the oxidation of a low-molecular reducer, NADH, during the enzymatic processes. Negative correlations were found between the intensity of bioluminescence and the content of ROS in bacteria and enzyme systems; an active role of ROS in the low-dose activation by thorium was discussed. The results contribute to radioecological potential of bioluminescence techniques adapted to study low-intensity radioactive exposures.

BACKGROUND: Thorium is ubiquitous in the environment and its relationship with birth defects is still under discussion. This study aimed to investigate the associations of maternal exposure to thorium with risk of neural tube defects (NTDs) by using a case-control study, as well as the relationship between thorium exposure and the indoor air pollution from coal combustion.
METHODS: This study was conducted in 11 local healthcare hospitals during 2003-2007 in Shanxi and Hebei provinces, China. A total of 774 mothers were included as participants who delivering 263 fetuses with NTDs including 123 with anencephaly, 115 with spina bifida, 18 with encephalocele, and 7 other NTD subtypes (cases), and 511 health fetuses without NTDs (controls). Their hair samples were collected as close as to the occipital posterior scalp, of which those grew from 3 months before to 3 months after conception was cut to measure the thorium concentration by inductively coupled plasma-mass spectrometry.
RESULTS: We found a higher hair thorium concentration in the total NTD cases with 0.901 (0.588-1.382) ng/g hair [median (inter-quartile range)] than that in the controls with a value of 0.621 (0.334-1.058) ng/g hair. Similar results were found for the three concerned NTD subtypes. Maternal hair thorium concentration above its median of the controls was associated with an increased risk of the total NTDs with an adjusted odds ratio of 1.80 [95% confidence interval (CI), 1.23-2.63)] by adjusting for all confounders. There was obvious dose-response relationship between maternal hair thorium concentration and the risk of total NTDs, as well as their two subtypes (i.e. anencephaly and spina bifida). Maternal hair thorium concentration was positive associated with their exposure level to indoor air pollution from coal combustion during cooking.
CONCLUSIONS: Overall, our findings revealed that maternal periconceptional thorium exposure was associated with the risk of NTDs in North China. Reducing the coal usage in the household cooking activities may decrease maternal thorium exposure level.