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1.
PLoS One ; 19(7): e0303595, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38995911

RESUMO

The reaction between the lixiviant and the minerals in the aquifer of In-situ uranium leaching (ISL) will result mineral dissolution and precipitation. ISL will cause changes in the chemical composition of groundwater and the porosity and permeability of aquifer, as well as groundwater pollution. Previous studies lack three-dimension numerical simulation that includes a variety of minerals and considers changes in porosity and permeability properties simultaneously. To solve these problems, a three-dimensional reactive transport model (RTM) which considered minerals, main water components and changes in porosity and permeability properties in Bayanwula mine has been established. The results revealed that: (1) Uranium elements were mainly distributed inside the mining area and had a weak trend of migration to the outside. The strong acidity liquid is mainly in the mining area, and the acidity liquid dissolved the minerals during migrating to the outside of the mining area. The concentration front of major metal cations such as K+, Na+, Ca2+ and Mg2+ is about 150m away from the boundary. (2) The main dissolved minerals include feldspar, pyrite, calcite, sodium montmorillonite and calcium montmorillonite. Calcite is the most soluble mineral and one of the sources of gypsum precipitation. Other minerals will dissolve significantly after calcite is dissolved. (3) ISL will cause changes in porosity and permeability of the mining area. Mineral dissolution raises porosity and permeability near the injection well. Mineral precipitation reduced porosity and permeability near the pumping well, which can plugging the pore throat and affect recovery efficiency negatively.


Assuntos
Água Subterrânea , Minerais , Mineração , Urânio , Urânio/análise , Urânio/química , Água Subterrânea/química , Água Subterrânea/análise , China , Minerais/análise , Minerais/química , Poluentes Radioativos da Água/análise , Poluentes Radioativos da Água/química , Porosidade
2.
Environ Sci Technol ; 58(28): 12633-12642, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38958591

RESUMO

As the number of coastal nuclear facilities rapidly increases and the wastewater from the Fukushima Nuclear Plant has been discharged into the Pacific Ocean, the nuclear environmental safety of China's marginal seas is gaining increased attention along with the heightened potential risk of nuclear accidents. However, insufficient work limits our understanding of the impact of human nuclear activities on the Yellow Sea (YS) and the assessment of their environmental process. This study first reports the 129I and 127I records of posthuman nuclear activities in the two YS sediments. Source identification of anthropogenic 129I reveals that, in addition to the gaseous 129I release and re-emission of oceanic 129I discharged from the European Nuclear Fuel Reprocessing Plants (NFRPs), the Chinese nuclear weapons testing fallout along with the global fallout is an additional 129I input for the continental shelf of the YS. The 129I/127I atomic ratios in the North YS (NYS) sediment are significantly higher than those in the other adjacent coastal areas, attributed to the significant riverine input of particulate 129I by the Yellow River. Furthermore, we found a remarkable 129I latitudinal disparity in the sediments than those in the seawaters in the various China seas, revealing that sediments in China's marginal seas already received a huge anthropogenic 129I from terrigenous sources via rivers and thus became a significant sink of anthropogenic 129I. This study broadens an insight into the potential impacts of terrigenous anthropogenic pollution on the Chinese coastal marine radioactive ecosystem.


Assuntos
Sedimentos Geológicos , Monitoramento de Radiação , Rios , Sedimentos Geológicos/química , Rios/química , China , Poluentes Radioativos da Água/análise , Oceanos e Mares , Humanos , Radioisótopos do Iodo/análise
3.
Environ Sci Technol ; 58(28): 12674-12684, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38965983

RESUMO

Although natural attenuation is an economic remediation strategy for uranium (U) contamination, the role of organic molecules in driving U natural attenuation in postmining aquifers is not well-understood. Groundwaters were sampled to investigate the chemical, isotopic, and dissolved organic matter (DOM) compositions and their relationships to U natural attenuation from production wells and postmining wells in a typical U deposit (the Qianjiadian U deposit) mined by neutral in situ leaching. Results showed that Fe(II) concentrations and δ34SSO4 and δ18OSO4 values increased, but U concentrations decreased significantly from production wells to postmining wells, indicating that Fe(III) reduction and sulfate reduction were the predominant processes contributing to U natural attenuation. Microbial humic-like and protein-like components mediated the reduction of Fe(III) and sulfate, respectively. Organic molecules with H/C > 1.5 were conducive to microbe-mediated reduction of Fe(III) and sulfate and facilitated the natural attenuation of dissolved U. The average U attenuation rate was -1.07 mg/L/yr, with which the U-contaminated groundwater would be naturally attenuated in approximately 11.2 years. The study highlights the specific organic molecules regulating the natural attenuation of groundwater U via the reduction of Fe(III) and sulfate.


Assuntos
Água Subterrânea , Mineração , Urânio , Poluentes Radioativos da Água , Água Subterrânea/química , Poluentes Radioativos da Água/análise , Compostos Orgânicos , Isótopos , Biodegradação Ambiental , Sulfatos
4.
Environ Monit Assess ; 196(8): 709, 2024 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-38970718

RESUMO

This article focuses on the study of the distribution of 137Cs in the bottom sediments of Arctic rivers of the Barents Sea basin (using the example of the Nenets Autonomous Okrug, Russian Arctic). This research is relevant due to the poorly studied region and the significant number of radiation-hazardous facilities in the Arctic zone of Russia, both those currently in operation and those that are "nuclear heritage sites". The study of 137Cs specific activity in bottom sediments was carried out in the period from 2020 to 2023 in the rivers Chizha, Nes, Vizhas, Oma, Pechora (river delta), as well as the rivers Kolva and Usa (first and second order tributaries, respectively, of the Pechora River). A total of 199 samples were collected. In addition to 137Cs specific activity, the samples were analysed for sediment particle size distribution, organic matter content, carbonate content and ash content. The 137Cs specific activity mainly ranged from the minimum detectable specific activity to 5.4 ± 0.8 Bq·kg-1. In the Nes River basin (Kaninskaya tundra), the 137Cs content in bottom sediments reached 36.0 ± 3.2 Bq·kg-1 (in the case of lake sediments) and 22.9 ± 3.7 Bq·kg-1 (in the case of river sediments), values that are higher than those of the North-West of Russia. Considering the large area of the study area (Kaninskaya tundra, Pechora river delta, southern part of Bolshezemelskaya tundra) and the similarity of physical and chemical parameters of the studied rivers, it is possible to assume the existence of a zone of increased radionuclide content in the Nes river basin. This may be due to the runoff from the Nes River catchment area, its hydrological features, and the accumulation of 137Cs in the small fractions of bottom sediments. The results confirm the conclusions of previous soil studies in the Nes river basin. The main sources of elevated 137Cs content are global atmospheric deposition and the Chernobyl Nuclear Power Plant accident.


Assuntos
Radioisótopos de Césio , Sedimentos Geológicos , Monitoramento de Radiação , Rios , Poluentes Radioativos da Água , Radioisótopos de Césio/análise , Rios/química , Sedimentos Geológicos/química , Poluentes Radioativos da Água/análise , Federação Russa , Regiões Árticas
5.
J Contam Hydrol ; 265: 104392, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38954926

RESUMO

More than 60% of worldwide uranium production is based on the In Situ Recovery mining technique. This exploitation method directly falls within the scope of the applications of reactive transport modelling to optimize uranium production and limit its associated environmental impact. We propose a modelling approach which is able to represent the natural evolution of an aquifer impacted by an ISR test performed using sulfuric acid. The model is calibrated on a 12 year-long data series obtained from 12 monitoring wells surrounding an ISR pilot cell. Through this process-based approach, we simulate the impact of several remediation strategies that can be considered in these contexts. In particular, we model the impact of Pump & Treat combined with reverse osmosis, as well as the circulation of non-impacted fluids through the reservoir with different operating strategies. Our approach allows to compare the effectiveness of these strategies. For this small-scale ISR pilot, monitored natural attenuation constitutes an interesting approach due to its faster pH recovery time with respect to Pump & Treat (5-10 years to pH ∼ 6), whose efficiency can be improved by the addition of exchangeable cations. Circulation of unimpacted fluids can reduce pH recovery times if performed for periods longer than the ISR exploitation and/or deployed with a delay. Combined with an economic evaluation of their deployment, this modelling approach can help the mining operator select and design optimal remediation strategies from an environmental and economical standpoint.


Assuntos
Recuperação e Remediação Ambiental , Água Subterrânea , Modelos Teóricos , Urânio , Recuperação e Remediação Ambiental/métodos , Mineração , Poluentes Radioativos da Água , Ácidos Sulfúricos/química
6.
J Contam Hydrol ; 265: 104390, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38959822

RESUMO

Uranium mainly comes from ISL of sandstone-type uranium deposits in China. The change of porosity and permeability caused by blockage of ore-bearing strata is one of the most serious problems in acid ISL of uranium. In this paper, the groundwater tracer test was carried out before and 1 year after ISL to explore the pore and permeability evolution characteristics of the ore-bearing layer during ISL. The test results showed that the leaching solution migrated along two seepage channels and the water-bearing medium was isotropic. After 1 year of ISL, the flow rate of the leaching solution decreased obviously. However, the flow rate of the leaching solution in slower channel decreased more than that in the faster channel in all directions, which was caused by the more adequate chemical reactions between the leaching solution and the minerals of the ore-bearing layer and the more corresponding precipitation in the slower channel. In addition, the flow rate along the direction of groundwater flow decreased less than that in the direction of vertical groundwater flow. This was closely related to the transformation of aquifer medium by hydrodynamic field. Initial stage of ISL, the occurrence of plugging is closely related to the precipitation-dissolution process of iron and aluminum minerals under the change of pH, which is accompanied by the continuous precipitation of gypsum.


Assuntos
Água Subterrânea , Mineração , Urânio , Urânio/química , China , Água Subterrânea/química , Permeabilidade , Movimentos da Água , Poluentes Radioativos da Água/análise , Poluentes Radioativos da Água/química , Porosidade
7.
Radiat Prot Dosimetry ; 200(11-12): 1052-1058, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016474

RESUMO

Groundwater is in direct contact with the soil and rocks that dissolve many compounds and minerals including uranium and its daughter products. 210Po is one of the decay products of 238U series that cause internal radiation dose in humans when consumed in the form of water and food, including sea food. Therefore, activities of 210Po have been studied in ground and surface water, and in food samples that are commonly used in Chamarajanagar region of Karnataka, India. The average 210Po concentration in bore well water samples and surface water samples are 3.21 and 1.85 mBq L-1, respectively. In raw rice and wheat, the average values of 210Po are 96 and 41 mBq kg-1, respectively. In millets and pulses, the average activity of 210Po is 157 and 79 mBq kg-1, respectively. Among food items, the highest activity of 1.3 kBq kg-1 is observed in marine crabs and the lowest activity of 2.6 mBq kg-1 is found in milk samples. The average ingestion dose due to 210Po in ground and surface water are 2.8 and 1.62 µSv y-1, respectively. The ingestion dose due to various food samples to the population is also calculated. Total ingestion dose due to 210Po to pure vegetarian population and general population are 38.09 and 590.80 µSv y-1, respectively. The concentration of 210Po in water samples and food samples of this region are in a comparable range with the world and Indian average values and lies well below the recommended guideline level.


Assuntos
Contaminação Radioativa de Alimentos , Polônio , Doses de Radiação , Monitoramento de Radiação , Poluentes Radioativos da Água , Índia , Contaminação Radioativa de Alimentos/análise , Polônio/análise , Monitoramento de Radiação/métodos , Poluentes Radioativos da Água/análise , Humanos , Água Subterrânea/análise
8.
Radiat Prot Dosimetry ; 200(11-12): 979-982, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016477

RESUMO

Determination of uranium isotopes in ground water plays a key role in assessment of geochemical condition of ground water and for estimating ingestion dose received by the general public because of uranium intake through drinking water. An attempt has been made in the present study to estimate isotopic composition and activity ratios (AR) of uranium isotopes by analysing the ground water samples using alpha spectrometry. Associated age-dependent ingestion dose was also calculated for the public of different age groups. 238U, 235U and 234U activity concentration was found to vary in the ranges of 5.85 ± 1.19 to 76.67 ± 4.16, < 0.90 to 3.15 ± 0.84 and 6.52 ± 1.25 to 107.02 ± 4.92 mBq/L, respectively. 235U/238U AR varies from 0.038 to 0.068 with an average of 0.047 which is close to 0.046 implies that uranium in the ground water is from natural origin. Uranium concentration was found to vary in the range of 0.47 ± 0.10 µg/L to 6.20 ± 0.34 µg/L with a mean value of 3.01 ± 0.23 µg/L, which is much lower than national as well as international recommendation value. Annual ingestion dose to the public of all age groups for uranium intake through drinking water ranges from 0.60 ± 0.11 to 19.50 ± 1.03 µSv/y.


Assuntos
Doses de Radiação , Monitoramento de Radiação , Urânio , Poluentes Radioativos da Água , Urânio/análise , Poluentes Radioativos da Água/análise , Humanos , Monitoramento de Radiação/métodos , Água Potável/análise , Água Subterrânea/análise , Criança , Adulto , Fatores Etários , Partículas alfa , Análise Espectral/métodos , Adolescente , Pré-Escolar , Adulto Jovem
9.
Radiat Prot Dosimetry ; 200(11-12): 1101-1107, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016491

RESUMO

This paper presents the concentration of uranium in 67 groundwater samples of Chamarajanagar district, Karnataka, India, estimated using an LED fluorimeter. The age-dependent ingestion dose to the population of the district is also studied. The concentration of uranium in groundwater varied from 0.20 to 57.50 µg L-1 with an average of 4.40 µg L-1. The annual ingestion dose due to uranium varies from 0.18 to 142.68 µSv y-1, with an average of 7.11 µSv y-1. The ingestion dose received by the population in the study area is less than the recommended level of 100 µSv y-1 by the World Health Organization (2011).


Assuntos
Água Subterrânea , Doses de Radiação , Monitoramento de Radiação , Urânio , Poluentes Radioativos da Água , Urânio/análise , Água Subterrânea/análise , Índia , Humanos , Poluentes Radioativos da Água/análise , Monitoramento de Radiação/métodos
10.
Radiat Prot Dosimetry ; 200(11-12): 1084-1089, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016501

RESUMO

Uranium occurs naturally in groundwater and surface water. Being a radioactive element, high uranium concentration can cause impact on human health. The health effects associated with consumption of uranium through water includes increased cancer risk and kidney toxicity. In view of this, an attempt was made in the present study to establish the level of radiological and chemical toxicity of uranium. Radiological toxicity was evaluated in terms of lifetime cancer risk and chemical toxicity through hazard quotient. For the said purpose, groundwater samples from the selected villages of the surrounding region of the Manchanabele reservoir, southwest of Bengaluru, were collected. The collected groundwater samples were analysed for Uranium mass concentration using Light emitting diode (LED) fluorimeter and is found to range from 0.88 to 581.47 ppb with a GM of 20.82 ppb. The result reveals that ~ 66% of the samples show concentration of uranium within the safe limit of 30 ppb as set by the World Health Organisation. The radiological risk estimated in terms of lifetime cancer risk is in the range of 0.0028 × 10-3 to 1.85 × 10-3 with a GM of 0.066 × 10-3. The chemical toxicity risk measured as lifetime annual daily dose is found to range from 0.03 to 21.65 µg per kg per d with a GM of 0.77 µg per kg per d.


Assuntos
Água Subterrânea , Monitoramento de Radiação , Urânio , Poluentes Radioativos da Água , Urânio/análise , Água Subterrânea/análise , Índia , Humanos , Poluentes Radioativos da Água/análise , Monitoramento de Radiação/métodos , Medição de Risco , Doses de Radiação , Exposição à Radiação/análise
11.
Radiat Prot Dosimetry ; 200(11-12): 994-1002, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016496

RESUMO

The geomorphology, geohydrology, lithology and ecological features of the area influence the uranium content in groundwater. The groundwater samples were collected from 75 locations of Davanagere district, Karnataka, India. Uranium analysis in the water samples was done using LED fluorimeter, based on fluorescence of dissolved uranyl salts. The uranium concentration in water samples varied from 18.41 to 173.21 µg L-1 with a geometric mean of 39.69 µg L-1. Higher uranium concentration in groundwater was observed in Harapanahalli and Jagalur taluk of Davanagere district, which falls in the Eastern Dharwar Craton, which is generally known to contain more radioactive minerals than the Western Dharwar Craton. The effective ingestion dose and lifetime cancer risk to the population were calculated using the obtained uranium concentration in drinking water.


Assuntos
Água Subterrânea , Doses de Radiação , Monitoramento de Radiação , Urânio , Poluentes Radioativos da Água , Urânio/análise , Água Subterrânea/análise , Índia , Poluentes Radioativos da Água/análise , Monitoramento de Radiação/métodos , Humanos , Água Potável/análise
12.
Radiat Prot Dosimetry ; 200(11-12): 1041-1046, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016506

RESUMO

Radionuclide activity of the selected radionuclides 238U, 232Th and 40K was measured in surface soil samples collected from 40 villages of the western part of Yadgir district of Karnataka. A 4″ × 4″ NaI (Tl) detector based on a gamma spectrometer is used for the estimation of radionuclides. The major type of soil in this region is sandy and red. The 222Rn activity concentrations in drinking water were determined by the Emanometry method. The 222Rn activity in ground water is found to vary from 1.73 to 155.6 Bql-1. The total annual effective doses because of 222Rn inhalation and ingestion range from 4.72 to 424.84 µSv y-1 with an average value of 108.8 µSv y-1, respectively. Among the sampling stations, Shahapur and Shorapur soil samples show higher activity values than the Kembhavi and Hunasagi sampling stations soil samples.


Assuntos
Água Potável , Radioisótopos de Potássio , Monitoramento de Radiação , Poluentes Radioativos do Solo , Poluentes Radioativos da Água , Índia , Poluentes Radioativos do Solo/análise , Monitoramento de Radiação/métodos , Água Potável/análise , Poluentes Radioativos da Água/análise , Radioisótopos de Potássio/análise , Tório/análise , Urânio/análise , Espectrometria gama , Humanos , Radônio/análise , Radiação de Fundo , Solo/química
13.
Radiat Prot Dosimetry ; 200(11-12): 1027-1033, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016514

RESUMO

Natural radionuclides are universally spread and can be found in varying levels in rock, soil and water depending on the geology. A potential health threat may be caused by them to humans on consumption of water, food and inhalation of air due to the presence of radionuclides. In the present study, an attempt has been made to study the distribution of 238U, 226Ra, 222Rn and 210Po in groundwater samples of Kodagu district, India. The activity concentrations of 238U, 226Ra, 222Rn and 210Po were found to vary from 0.44 to 8.81 µg L-1, 0.71 to 7.66 mBq L-1, 1.54 to 9.61 Bq L-1 and 0.47 to 4.35 mBq L-1, respectively. The associated dose due to radiation was assessed and was observed to be below the recommended standards. The total effective dose to the population was calculated and was found to be less than the recommended WHO standard of 100 mSv.


Assuntos
Água Subterrânea , Polônio , Doses de Radiação , Monitoramento de Radiação , Rádio (Elemento) , Urânio , Poluentes Radioativos da Água , Rádio (Elemento)/análise , Água Subterrânea/análise , Índia , Poluentes Radioativos da Água/análise , Monitoramento de Radiação/métodos , Urânio/análise , Humanos , Polônio/análise , Radônio/análise
14.
Radiat Prot Dosimetry ; 200(11-12): 1108-1113, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016516

RESUMO

The groundwater is being used for drinking and irrigation purposes in vast swathes of the Aravalli Mountain range. Since the radioisotope presence in groundwater is affected by the local mining processes, the radiation monitoring in groundwater of mining regions is of paramount importance. In the present work, we have estimated the 222Rn presence in the mining region of Aravalli in the southern part of Haryana. We measured the Radon concentration in 51 water samples from the intended area using the RAD7 alpha detector. The measured radon concentration in some of the water samples collected from the vicinity of the mining zone is higher than that of the United Nations Scientific Committee on the Effects of Atomic Radiation recommended value. Furthermore, we have estimated the annual effective doses for the lungs and stomach contributed by ingestion and inhalation. Though the calculated dose values in collected samples are not in the critical range, further monitoring of background radiation in the Aravalli region is required.


Assuntos
Água Subterrânea , Pulmão , Mineração , Doses de Radiação , Monitoramento de Radiação , Radônio , Estômago , Poluentes Radioativos da Água , Radônio/análise , Poluentes Radioativos da Água/análise , Índia , Humanos , Monitoramento de Radiação/métodos , Água Subterrânea/análise , Estômago/efeitos da radiação , Pulmão/efeitos da radiação
15.
Sci Total Environ ; 946: 174406, 2024 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-38964395

RESUMO

The remediation of groundwater subject to in situ leaching (ISL) for uranium mining has raised extensive concerns in uranium mill and milling. This study conducted bioremediation through biostimulation and bioaugmentation to the groundwater in an area in northern China that was contaminated due to uranium mining using the CO2 + O2 neutral ISL (NISL) technology. It identified the dominant controlling factors and mechanisms driving bioremediation. Findings indicate that microorganisms can reduce the uranium concentration in groundwater subject to NISL uranium mining to its normal level. After 120 days of bioaugmentation, the uranium concentration in the contaminated groundwater fell to 0.36 mg/L, achieving a remediation efficiency of 91.26 %. Compared with biostimulation, bioaugmentation shortened the remediation timeframe by 30 to 60 days while maintaining roughly the same remediation efficiency. For groundwater remediation using indigenous microbial inoculants, initial uranium concentration and low temperatures (below 15 °C) emerge as the dominant factors influencing the bioremediation performance and duration. In settings with high carbonate concentrations, bioremediation involved the coupling of multiple processes including bioreduction, biotransformation, biomineralization, and biosorption, with bioreduction assuming a predominant role. Post-bioremediation, the relative abundances of reducing microbes Desulfosporosinus and Sulfurospirillum in groundwater increased significantly by 10.56 % and 6.91 %, respectively, offering a sustainable, stable biological foundation for further bioremediation of groundwater.


Assuntos
Biodegradação Ambiental , Água Subterrânea , Urânio , Poluentes Radioativos da Água , Água Subterrânea/química , Urânio/metabolismo , China , Poluentes Radioativos da Água/metabolismo , Poluentes Radioativos da Água/análise , Mineração
16.
J Environ Radioact ; 277: 107451, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38851005

RESUMO

Strontium-90 (90Sr) is a major contaminant at nuclear legacy sites. The mobility of 90Sr is primarily governed by sorption reactions with sediments controlled by high surface area phases such as clay and iron oxides. Sr2+ adsorption was investigated in heterogeneous unconsolidated aquifer sediments, analogous to those underlying the UK Sellafield nuclear site, with grainsizes ranging from gravels to clays. Batch sorption tests showed that a linear Kd adsorption model was applicable to all grainsize fractions up to equilibrium [Sr] of 0.28 mmol L-1. Sr2+ sorption values (Kd; Langmuir qmax) correlated well with bulk sediment properties such as cation exchange capacity and surface area. Electron microscopy showed that heterogeneous sediments contained porous sandstone clasts with clay minerals (i.e. chlorite) providing an additional adsorption capacity. Therefore, gravel corrections that assumed that the > 2 mm fractions are inert were not appropriate and underestimated Kd(bulk) adsorption coefficients. However, Kd (<2 mm) values measured from sieved sediment fractions, were effectively adjusted to within error of Kd (bulk) using a surface area dependant gravel correction based on particle size distribution data. Amphoteric pH dependent Sr2+ sorption behaviour observed in batch experiments was consistent with cation exchange modelling between pH 2-7 derived from the measured cation exchange capacities. Above pH 7 model fits were improved by invoking a coupled cation exchange/surface complexation which allowed for addition sorption to iron oxide phases. The overall trends in Sr2+ sorption (at pH 6.5-7) produced by increasing solution ionic strength was also reproduced in cation exchange models. Overall, the results showed that Sr2+ sorption to heterogeneous sediment units could be estimated from Kd (<2 mm) data using appropriate gravel corrections, and effectively modelled using coupled cation exchange and surface complexation processes.


Assuntos
Sedimentos Geológicos , Água Subterrânea , Radioisótopos de Estrôncio , Estrôncio , Poluentes Radioativos da Água , Sedimentos Geológicos/química , Água Subterrânea/química , Adsorção , Estrôncio/química , Poluentes Radioativos da Água/análise , Poluentes Radioativos da Água/química , Radioisótopos de Estrôncio/química , Radioisótopos de Estrôncio/análise , Tamanho da Partícula , Modelos Químicos
17.
J Environ Radioact ; 277: 107466, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38838510

RESUMO

Plutonium, as well as fission products such as 137Cs, had been released into the earth environment in 1945 after the first atmospheric nuclear explosion of plutonium bomb in the desert of New Mexico (USA, July 16) and later over Nagasaki (August 9), followed then by many other explosions. Thus, plutonium cycling in the atmosphere and ocean has become a major public concern as a result of the radiological and chemical toxicity of plutonium. However, plutonium isotopes and 137Cs are important transient tracers of biogeochemical and physical processes in the environment, respectively. In this review, we show that both physical and chemical approaches are needed to comprehensively understand the behaviors of plutonium in the atmosphere and ocean. In the atmosphere, plutonium and 137Cs attach with aerosols; thus, plutonium moves according to physical and chemical processes in connection with aerosols; however, since plutonium is a chemically reactive element, its behavior in an aqueous environment is more complicated, because biogeochemical regulatory factors, in addition to geophysical regulatory factors, must be considered. Meanwhile, 137Cs is chemically inert in aqueous environments. Therefore, the biogeochemical characteristics of plutonium can be elucidated through a comparison with those of 137Cs, which show conservative properties and moves according to physical processes. Finally, we suggest that monitoring of both plutonium and 137Cs can help elucidate geophysical and biogeochemical changes from climate changes.


Assuntos
Poluentes Radioativos do Ar , Atmosfera , Plutônio , Monitoramento de Radiação , Plutônio/análise , Atmosfera/química , Poluentes Radioativos do Ar/análise , Poluentes Radioativos da Água/análise , Radioisótopos de Césio/análise , Oceanos e Mares
18.
Chemosphere ; 361: 142544, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38844100

RESUMO

Nuclear energy is playing an increasingly important role on the earth, but the nuclear plants leaves a legacy of radioactive waste pollution, especially uranium-containing pollution. Straw biochar with wide sources, large output, low cost, and easy availability, has emerged as a promising material for uranium extraction from radioactive wastewater, but the natural biomass with suboptimal structure and low content of functional groups limits the efficiency. In this work, microbial etch was first came up to regulate the biochar's structure and function. The surface of the biochar becomes rougher and more microporous, and the mineral contents (Ca, P) indirectly increased by microbial etch. The biochar was modified by calcium phosphate and exhibited a remarkable uranium extraction capacity of 590.8 mg g-1 (fitted value). This work provides a cost-effective and sustainable method for preparing functionalized biochar via microbial etch, which has potential for application to uranium extraction from radioactive wastewater.


Assuntos
Carvão Vegetal , Urânio , Águas Residuárias , Carvão Vegetal/química , Urânio/química , Águas Residuárias/química , Resíduos Radioativos/análise , Poluentes Radioativos da Água , Fosfatos de Cálcio/química
19.
J Environ Radioact ; 277: 107465, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38833881

RESUMO

The activity concentration of 3H in water samples collected from places unaffected by nuclear activities or for human consumption can be very low. In these cases, determination procedures must achieve a Minimum Detectable Activity (MDA) low enough to ensure that 3H is accurately determined. In this paper, we present a method that uses a new Liquid Scintillation Spectrometer (LSC in what follows): the Quantulus GCT 6220. Furthermore, a new liquid scintillation cocktail, the ProSafe LT+, has been tested for 3H measurement, showing to be a good option for the determination of low levels of this radionuclide. The MDAs achieved are low enough to enable the measurement of very low levels of 3H in recent environmental water. The results obtained using a Quantulus GCT 6220 and Prosafe LT + are compared to those obtained with a Quantulus 1220 and Prosafe HC + as liquid scintillation cocktail.


Assuntos
Monitoramento de Radiação , Contagem de Cintilação , Trítio , Poluentes Radioativos da Água , Contagem de Cintilação/métodos , Contagem de Cintilação/instrumentação , Poluentes Radioativos da Água/análise , Monitoramento de Radiação/métodos , Monitoramento de Radiação/instrumentação , Trítio/análise
20.
J Environ Radioact ; 277: 107459, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38833882

RESUMO

The objective of this study was to investigate the effects of gamma irradiation on the aquatic environment. We used three wild fish species to compare phenotypic responses with a fish model such as Danio rerio. We focused on embryonic development, a sensitive life stage to stressors like ionizing radiation, to evaluate the effects of exposure to 0.5 and 5 mGy h-1 on Arctic char, trout and stickleback embryos from fertilization to free-swimming larvae. Irradiation did not cause mortality but induced an acceleration of hatching in the three species. These new data on wild species, obtained under comparable irradiation conditions, did not go against the threshold values for the protection of freshwater aquatic ecosystems. Moreover, irradiation caused inter-specific sublethal effects, such as an increase in non-eyed egg proportion in Arctic char, an increase in the incubation period in trout and an acceleration of larval mortality in stickleback. The consequences of these early effects on the adult stage remain to be studied.


Assuntos
Raios gama , Animais , Smegmamorpha , Peixes , Poluentes Radioativos da Água/toxicidade , Truta , Larva/efeitos da radiação
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