Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.867
Filtrar
1.
Environ Monit Assess ; 194(2): 112, 2022 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-35050408

RESUMEN

Naturally occurring radionuclides and metals have adverse human health impacts when they occur at higher activity and concentration above the threshold value, respectively, in the water supply system. This study aimed to establish the baseline radionuclide and metal content in rocks, soils, and water in the Thyspunt area of the Eastern Cape Province, South Africa, which is selected as a potential site for the development of a nuclear power plant. Extensive sampling of rocks, soils, groundwater, and surface water was conducted in the area. The employed methods of sample analyses include ICP-MS, gamma-ray spectrometery (RS 230), and accelerator mass spectrometry. The results indicate that the Ceres Subgroup shale and the Skurwerburg formation quartzite of the Table Mountain Group (TMG) contain the highest activity of most radionuclides, including 238U, 235U, 234U, 226Ra, 232Th, and 210Pb; these are linked to the natural geochemistry of the rocks that have been facilitated by the low-grade metamorphism to which the local geology was subjected. The metamorphism-related radionuclide enrichment is also apparent in the soils and groundwater associated with these rocks. The activity of the radiotoxic and carcinogenic uranium (238U and 235U) and radium (226Ra and 224Ra) isotopes in water was found to be well above the WHO guideline of 0.03 and 1 Bq/L, respectively. The exposure dose rate was the highest in the Ceres Subgroup shales (185.7 nS/h), and this is linked to the elevated natural radioactivity in the rocks. The estimate of the ingestion-related effective dose indicates high doses associated with the uranium and radium isotopes, thus signifying the potential adverse impact on human health associated with the ingestion of the widely used groundwater in the area.


Asunto(s)
Monitoreo de Radiación , Radiactividad , Contaminantes Radiactivos del Agua , Humanos , Radioisótopos , Sudáfrica , Contaminantes Radiactivos del Agua/análisis
2.
Sci Total Environ ; 806(Pt 1): 150508, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34844309

RESUMEN

Polonium-210 (210Po) is a radionuclide sentinel as it bioaccumulates in marine organisms, thereby being the main contributor to committed dietary doses in seafood consumers. Although seafood and marine mammals are an important part of the traditional Inuit diet, there is a general lack of information on the 210Po concentrations in the Greenlandic marine food chain leading to the human consumer. Here, we determine background 210Po concentrations in edible parts of different marine organisms from Greenland and provide a dose assessment. Blue mussels (Mytilus edulis), organs of ringed seal (Pusa hispida) and polar bear (Ursus maritimus) displayed significantly elevated 210Po concentrations in respect to all other studied organisms (p < 0.001). 210Po concentrations ranged from 0.02 Bq kg-1, w.w. in Greenland halibut (Reinhardtius hippoglossoides) muscle to 78 Bq kg-1, w.w. and 202 Bq kg-1, w.w. in ringed seal muscle and kidneys, respectively. 210Po concentration ratio for edible parts increases in the order bladderwrack (Fucus Vesiculosus), northern shrimp (Pandalus borealis), blue mussels, and from fish species to ringed seal and polar bear. 210Po distribution in fish, ringed seal, and polar bear follows a general pattern, the lowest concentrations were in muscle, and the highest concentrations were in the organs involved in metabolism. The derived 210Po annual absorbed dose in edible parts of studied marine organisms are several orders of magnitude lower than the recommended dose rate screening value of 10 µGy h-1. Effective doses from intake of 210Po to Greenland average children (1.4 mSv y-1), and high seafood and marine mammal consumers (2 mSv y-1 for adults and 3.6 mSv y-1 for children) are higher than the world average annual effective dose due to ingestion of naturally occurring radionuclides.


Asunto(s)
Polonio , Contaminantes Radiactivos del Agua , Animales , Biota , Groenlandia , Humanos , Polonio/análisis , Contaminantes Radiactivos del Agua/análisis
3.
Sci Total Environ ; 806(Pt 1): 150482, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34844331

RESUMEN

This work reports the first high-resolution deposition records of anthropogenic uranium (236U and 233U) in a sediment core taken at the continental slope of the Philippine Sea off Mindanao Island in the equatorial northwest Pacific Ocean. Two notable peaks were observed in both profiles of 236U and 233U concentrations, with a narrower peak in 1951-1957 corresponding to close-in Pacific Proving Grounds (PPG) signal, and a broader peak in 1960s-1980s corresponding to the global fallout from nuclear weapons testing. 236U and 233U areal cumulative inventories in the studied sediment core are (2.79 ± 0.20) ∙ 1012 atom ∙ m-2 and (3.12 ± 0.41) ∙ 1010 atom ∙ m-2, respectively, about 20-30% of reported 233U and 236U inventories from the direct global fallout deposition. The overall 233U/236U atomic ratios obtained in this work vary within (0.3-3.5) âˆ™ 10-2, with an integrated 233U/236U atomic ratio of (1.12 ± 0.17) âˆ™ 10-2. The contribution from global fallout and close-in PPG fallout to 236U in the sediment core is estimated to be about 69% and 31%, respectively. We believe the main driving process for anthropogenic uranium deposition in the Philippine sediment is continuous scavenging of dissolved 236U from the surface seawater by sinking particles.


Asunto(s)
Plutonio , Monitoreo de Radiación , Ceniza Radiactiva , Uranio , Contaminantes Radiactivos del Agua , Océano Pacífico , Filipinas , Plutonio/análisis , Ceniza Radiactiva/análisis , Contaminantes Radiactivos del Agua/análisis
4.
Water Res ; 210: 117987, 2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-34954368

RESUMEN

The Baltic Sea receives substantial amounts of hazardous substances and nutrients, which accumulate for decades and persistently impair the Baltic ecosystems. With long half-lives and high solubility, anthropogenic uranium isotopes (236U and 233U) are ideal tracers to depict the ocean dynamics in the Baltic Sea and the associated impacts on the fates of contaminants. However, their applications in the Baltic Sea are hampered by the inadequate source-term information. This study reports the first three-dimensional distributions of 236U and 233U in the Baltic Sea (2018-2019) and the first long-term hindcast simulation for reprocessing-derived 236U dispersion in the North-Baltic Sea (1971-2018). Using 233U/236U fingerprints, we distinguish 236U from the nuclear weapon testing and civil nuclear industries, which have comparable contributions (142 ± 13 and 174 ± 40 g) to the 236U inventory in modern Baltic seawater. Budget calculations for 236U inputs since the 1950s indicate that, the major 236U sources in the Baltic Sea are the atmospheric fallouts (∼1.35 kg) and discharges from nuclear reprocessing plants (> 211 g), and there is a continuous sink of 236U to the anoxic sediments (589 ± 43 g). Our findings also indicate that the limited water renewal endows the Baltic Sea a strong "memory effect" retaining aged 236U signals, and the previously unknown 236U in the Baltic Sea is likely attributed to the retention of the mid-1990s' discharges from the nuclear reprocessing plants. Our preliminary results demonstrate the power of 236U-129I dual-tracer in investigating water-mass mixing and estimating water age in the Baltic Sea, and this work provides fundamental knowledge for future 236U tracer studies in the Baltic Sea.


Asunto(s)
Contaminantes Radiactivos del Agua , Países Bálticos , Simulación por Computador , Ecosistema , Agua de Mar , Contaminantes Radiactivos del Agua/análisis
5.
Sci Total Environ ; 811: 152407, 2022 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-34914992

RESUMEN

One recent way of reconstructing the historical impact of aboveground nuclear weapons testing (ANWT) in places lacking historical data is by measuring 129I in natural archives such as coral cores. However, discussions arising from 129I in corals remain qualitative or semi-quantitative, which do not maximize the potential information derivable from the data. In this study, we construct a mathematical model that simulates the 129I bomb peaks from the Pacific Proving Grounds (PPG) tests, as observed in available coral core data from the east (Baler) and west (Parola) sides of the Philippines. Results show that the model can determine the expected increase in 129I/127I ratio in the Philippines per megaton of ANWT detonated in the PPG; confirm time lags for each major transport pathway from the PPG to the Philippines, indicating when to expect the radioactivity spike after detonation; and determine the most significant transport pathway from the PPG to each coral location. This work increases the application and significance of 129I/127I coral core data by deriving quantitative information about the magnitude, timing, and transport pathways of radioactivity from the ANWT site to the coral location. In the future, the model can be expanded to simulate other 129I sources besides ANWT.


Asunto(s)
Antozoos , Armas Nucleares , Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Animales , Arrecifes de Coral , Radioisótopos de Yodo/análisis , Océano Pacífico , Filipinas , Contaminantes Radiactivos del Agua/análisis
6.
Environ Pollut ; 295: 118673, 2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-34923059

RESUMEN

The derivation of sediment quality guideline values (SQGVs) presents significant challenges. Arguably the most important challenge is to conduct toxicity tests using contaminated sediments with physico-chemistry that represents real-world scenarios. We used a novel metal spiking method for an experiment that ultimately aims to derive a uranium SQGV. Two pilot studies were conducted to inform the final spiking design, i.e. percolating a uranyl sulfate solution through natural wetland sediments. An initial pilot study that used extended mixing equilibration phases produced hardened sediments not representative of natural sediments. A subsequent percolation method produced sediment with similar texture to natural sediment and was used as the method for spiking the sediments. The range of total recoverable uranium (TR-U) concentrations achieved was 8-3200 mg/kg. This reflected the concentrations found in natural wetlands and water management ponds found on a uranium mine site and was above natural levels. Dilute-acid extractable uranium (AE-U) concentrations were >80% of total concentrations, indicating that much of the uranium in the spiked sediment was labile and potentially bioavailable. The portion of TR-U extractable as AE-U was similar at the start and end of the 4.5-month field-deployment. Porewater uranium (PW-U) analyses indicated that partition coefficients (Kd) were 2000-20,000 L/kg, and PW-U was greater in post- than pre-field-deployed samples when TR-U was ≤1500 mg/kg, indicating the binding became weaker during the field-deployment period. At higher spiked-U concentrations, the PW-U was lower post-field-deployment. Comparing the physico-chemical data of the spiked sediments with environmental monitoring data from sediments in the vicinity of a uranium mining operation indicated that they were representative of sediments contaminated by mining and that the U-spiked sediments had a clear U concentration gradient. This confirmed the suitability of the spiking procedure for preparing sediments that were suitable for deriving a SQGV for uranium.


Asunto(s)
Uranio , Contaminantes Radiactivos del Agua , Sedimentos Geológicos , Proyectos Piloto , Uranio/análisis , Contaminantes Radiactivos del Agua/análisis , Humedales
7.
Ecotoxicol Environ Saf ; 229: 113086, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34929505

RESUMEN

An attempt has been made in this study to evaluate the factors favoring the uranium mobilization into the groundwater of Northwest India using uranium isotope activity ratio (234U/238U), radon (222Rn) and environmental isotopes of water (2H, 18O and 3H). The values range from 23 - 597 µg/L for total uranium and 634-3210 Bq/m3 for radon and the corresponding annual effective dose is estimated to be 18.9-490 µSv/a and 6.2-31.5 µSv/a respectively. Uranium activity ratio (UAR) varies from 0.68 - 1.17 and maximum samples indicate secular equilibrium. Environmental isotopic data indicates that the source to groundwater is vertical percolation of rainwater in the case of shallow zone while regional flows from outcrop areas recharge the deep groundwater. A wide scatter is noticed in environmental 3H content (0.23-6.62 TU) indicating both fast and sluggish water flows. The UAR phase diagram suggests that leaching process controls the uranium mobilization into the groundwater. The correlations among UAR, uranium and Uexcess further indicate oxidative nature of leaching process. Statistical treatment of the obtained data along with available geochemical and isotope evidences suggest that source of uranium is common but the driving processes are different for shallow and deep zone. Influences of root zone CO2, oxic species from irrigation return flows and water level fluctuations are also evaluated. Low uranium, low UAR, low 3H and high 222Rn activity in deep zone suggest uranium being released from the roll front as well as transported from outcrop regions. This study highlights the application of uranium isotope ratio, radon and environmental isotopes in assessing vulnerability of alluvial aquifers towards uranium contamination.


Asunto(s)
Agua Subterránea , Radón , Uranio , Contaminantes Radiactivos del Agua , India , Radón/análisis , Medición de Riesgo , Uranio/análisis , Contaminantes Radiactivos del Agua/análisis
8.
Environ Pollut ; 292(Pt B): 118431, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34743968

RESUMEN

The fate and behavior of radioactive cesium (Cs) in the water environment are of great concern. The involvement of bacteria regarding their accumulation capability for this element is the most fundamental factor that needs to be clarified even for exploring the interactions between many environmental factors that involve together in governing the transport and distribution of Cs. As the first systematical study that aimed to evaluate the accumulation capability of environmental bacteria for Cs, bacteria in the sediment of a freshwater reservoir and coastal water environment were isolated and multiplied for contact experiment with Cs under different temperature conditions (5, 25, and 35 °C). The accumulation concentration of Cs in bacteria from freshwater sediment varied in 3.95 × 10-6 to 5.68 × 10-4ng-Cs/cell, and that from coastal sediment in 1.52 × 10-6 to 7.41 × 10-4ng-Cs/cell, indicating obvious differences among bacterial species. Bacteria of coastal sediment possessed higher accumulation capability for Cs than bacteria from freshwater sediment, and temperature dependency was confirmed for bacteria from coastal sediment. The findings of this study have great reference value for better understanding and controlling the fate and behavior of radioactive Cs associated with bacteria in the water environment.


Asunto(s)
Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Bacterias , Cesio/análisis , Radioisótopos de Cesio/análisis , Agua Dulce , Sedimentos Geológicos , Contaminantes Radiactivos del Agua/análisis
9.
Environ Pollut ; 292(Pt B): 118479, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34752791

RESUMEN

The 2011 Tohoku earthquake-tsunami and the subsequent nuclear accident at the Fukushima Dai-ichi Nuclear Power Station (FDNPS) led to large-scale radionuclide contamination of the marine and freshwater environment. Monitoring studies of marine food products in the Fukushima region have generally demonstrated a declining trend in radiocaesium concentrations. However, the accumulation and elimination of radiocaesium and potential biological effects remain poorly understood for freshwater biota inhabiting highly contaminated areas at Fukushima. Consequently, the present study aimed to assess radiocaesium accumulation and developmental effects on the commercially important catadromous Japanese mitten crab, Eriocheir japonica. E. japonica were collected from four sites along a gradient of radionuclide contamination 4-44 km in distance from the FDNPS in 2017. To determine potential developmental effects, fluctuating asymmetry (FA) was used as a measure of developmental stability. Combined 134Cs and 137Cs values for whole E. japonica from highly contaminated sites 4 and 16 km in distance from the FDNPS were 3040 ± 521 and 2250 ± 908 Bq kg-1 wet weight respectively, 30 and 22 times greater than the Japanese standard limit of 100 Bq kg-1. Estimated total dose rates based on radiocaesium concentrations in whole crabs and sediment ranged from 0.016 to 37.7 µGy h-1. No significant relationship between radiocaesium accumulation and FA was recorded, suggesting that chronic radiation exposure at Fukushima is not inducing developmental effects in E. japonica as measured using fluctuating asymmetry. Furthermore, estimated dose rates were below proposed regulatory limits where significant deleterious effects are expected. The present study will aid in the understanding of the long-term consequences of radiation exposure for non-human biota and the management of radioactively contaminated environments.


Asunto(s)
Accidente Nuclear de Fukushima , Exposición a la Radiación , Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Japón , Contaminantes Radiactivos del Agua/análisis
10.
Environ Res ; 203: 111791, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34333012

RESUMEN

Uranium (U) in groundwater is hazardous to human health, especially if it is present in drinking water. The semiarid regions of southern India chiefly depend on groundwater for drinking purposes. In this regard, a comprehensive sampling strategy was adopted to collect groundwater representing different lithologies of the region. The samples were collected in two different seasons and analysed for major and minor ions along with total U in the groundwater. Two samples during pre monsoon (PRM) and seven samples during post monsoon (POM) had U > 30 µgL-1, which is above the World Health Organization's provisional guideline value. The high concentration of U (188 µgL-1) was observed in the alluvial formation though a few samples showed the release of U near the pink granite (39 µgL-1) and the concentration was low in the lateritic formation (10 µgL-1). The uranyl carbonato complexes UO2(CO3)22- and UO2(CO3)34- were associated with high pH which facilitated the transport of U into groundwater especially during POM. U3O8 is the major form observed in groundwater compared to either UO2 or UO3 in the both seasons. The uranium oxides were observed to be more prevalent at the neutral pH. Though U concentration increases with pH, it is mainly governed by the redox conditions. The principal component analysis (PCA) analysis also suggested redox conditions in groundwater to be the major process facilitating the U release mechanism regardless of the season. The POM season has an additional source of U in groundwater due to the application of nitrogenous fertilizers in the alluvium region. Furthermore, redox mobilization factor was predominantly observed near the coastal region and in the agricultural regions. The process of infiltration of the fertilizer-induced U was enhanced by the agricultural runoff into the surface water bodies in the region. Health risk assessment was also carried out by determining annual effective dose rate, cancer mortality risk, lifetime average daily dose and hazard quotient to assess the portability of groundwater in the study area. Artificial recharge technique and reducing the usage of chemical based fertilizers for irrigation are suggested as sustainable plans to safeguard the vulnerable water resource in this region.


Asunto(s)
Agua Subterránea , Uranio , Contaminantes Químicos del Agua , Contaminantes Radiactivos del Agua , Monitoreo del Ambiente , Fertilizantes , Humanos , India , Medición de Riesgo , Uranio/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad , Contaminantes Radiactivos del Agua/análisis , Contaminantes Radiactivos del Agua/toxicidad
11.
Sci Total Environ ; 806(Pt 3): 151216, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34717992

RESUMEN

The distributions of dissolved 137Cs in river, nearshore, and offshore waters on the east and west coasts of the Japanese island of Honshu were studied in 2018-2021, 7-10 years after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. On the east side along the north western North Pacific (Fukushima Prefecture), estuarine processes, including desorption from riverine particles and dissolution into pore water from riverine particles that had settled to the seafloor, contributed to the maintenance of high dissolved 137Cs activities in nearshore and offshore waters. A survey and mass-balance calculation in a semi-enclosed estuarine area, the Matsukawa-ura, in the northern part of Fukushima, provided convincing evidence that rivers contributed to the influx of 137Cs to coastal waters. In contrast, the extremely low activities of dissolved and particulate 137Cs in the Tedori River of Ishikawa Prefecture on the western side of Japan along the Japan Sea suggested that inputs of riverine 137Cs made a negligible contribution to the increase of dissolved 137Cs activities in the nearshore and offshore waters. The relatively high dissolved 137Cs activities observed in the offshore waters of the Japan Sea were due to movement of FDNPP-derived 137Cs into the Japan Sea via the Tsushima Warm Current. Mechanisms controlling the distributions of 137Cs activities in coastal waters of the eastern and western sides of Japan therefore differ.


Asunto(s)
Accidente Nuclear de Fukushima , Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Japón , Contaminantes Radiactivos del Agua/análisis
12.
Sci Total Environ ; 806(Pt 3): 151344, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34728196

RESUMEN

Estimation of 3H discharge from river catchments is important to evaluate the effect of Fukushima Dai-ichi discharge and future planned 3H release to the ocean on the coastal environment. Using a previously developed model based on the tank model and observed 3H concentration in river water, the 3H discharge from the Abukuma River and 13 other rivers in the Fukushima coastal region were estimated from June 2013 to March 2020. The 3H discharge from catchments of the Abukuma River and 13 other rivers in the Fukushima coastal region during 2014-2019 were estimated to be 1.2-4.0 TBq/y. These values were approximately 2-22 times larger than the annual 3H discharge from the Fukushima Dai-ichi after 2016, indicating the significance of 3H discharge from the catchments through the rivers. This estimation is expected to be useful to evaluate and predict 3H concentrations and inventories in the Fukushima coastal region for consideration of planned 3H release to the ocean.


Asunto(s)
Accidente Nuclear de Fukushima , Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Japón , Ríos , Agua de Mar , Contaminantes Radiactivos del Agua/análisis
13.
J Environ Radioact ; 241: 106775, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34781091

RESUMEN

This study aimed to investigate the dynamics of 137Cs around banks along an agricultural canal for paddy fields in Iitate, Fukushima, Japan. Five plots (2.4-12.6 m2) on the banks were monitored intermittently during six time periods from May 2018 to November 2019. We directly collected runoff water samples discharged from the banks followed by partitioning it into particulate and dissolved fractions and determining 137Cs in them. To investigate the source of 137Cs in the runoff water, we sequentially extracted 137Cs in various chemical forms from litter samples collected on the banks. The results showed that the discharge rates of the dissolved 137Cs per unit area from the plots were lower than those observed at the downstream of the agricultural canal, whereas more than 50% of the 137Cs discharged from the plots was in the dissolved fraction. Moreover, the results indicate that 137Cs stored in the standing plants and the litter was the primary source of the dissolved 137Cs discharged into the agricultural canal. The concentrations of the water-soluble 137Cs in the litter per plot area may have been retained by the sufficiently higher concentrations of 137Cs in litter in other chemical forms and those in the standing plants, which are the source of the litter.


Asunto(s)
Accidente Nuclear de Fukushima , Monitoreo de Radiación , Contaminantes Radiactivos del Suelo , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Japón , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis
14.
Chemosphere ; 286(Pt 1): 131514, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34311394

RESUMEN

A baseline study on anthropogenic radioactivity in the Namibian marine ecosystem, which is part of the northern Benguela upwelling system, known as one of the most productive ocean areas in the world, has been performed. A scientific cruise carried out in 2014 covering inshore and offshore areas, exhibiting different oceanographic features, has provided a basis for better understanding the distributions, ratios and inventories of six anthropogenic radionuclides (90Sr, 137Cs, 238Pu, 239Pu, 240Pu and 241Am) in seawater. Although 3H was also measured, due to extremely low levels, its behaviour was not studied. The main source of 90Sr, 137Cs, 239Pu, 240Pu and 241Am in the samples analysed was proven to be global fallout, a finding further confirmed by 240Pu/239Pu and 90Sr/137Cs ratios. Furthermore, the 238Pu SNAP-9A satellite accident signal was confirmed once again through the determination of the 238Pu/239+240Pu activity ratio. Inshore and offshore samples showed different patterns due to the unique oceanographic features of this upwelling system. The levels of anthropogenic radionuclides, comprehensively assessed for the first time in this region, are comparable with the few existing data and filled a critical gap for the Southern Atlantic Ocean.


Asunto(s)
Plutonio , Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Ecosistema , Namibia , Plutonio/análisis , Agua de Mar , Radioisótopos de Estroncio , Contaminantes Radiactivos del Agua/análisis
15.
Chemosphere ; 287(Pt 3): 132323, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34563776

RESUMEN

This study investigated the concentration of radon (222Rn) in hot springs water. For this purpose, 222Rn concentration was measured using the RAD7 (Durridge Company, USA) in the water of hot springs located in Tata Pani, Gilgit (n = 4), and Garam Chashma, Chitral (n = 6), northern Pakistan. Water samples from the springs (background, n = 3) were also collected and analyzed for 222Rn concentration 40-50 km away from the hot springs in Gilgit and Chitral, northern Pakistan, to be used as background/reference concentration. The determined 222Rn in hot springs water surpassed the threshold of maximum contamination level (MCL, 11.1 Bq/L) set by the United States Environmental Protection Agency (US-EPA) in 100% samples collected from Tata Pani, Gilgit, and Garam Chashma, Chitral sites. Soil 222Rn along with the hot springs exhibited a decreasing trend with increasing distance. 222Rn concentration in hot springs water was used to calculate the exposure doses of human health through ingestion and inhalation pathways. The total effective dose for human (EWT) of 222Rn contaminated water consumption was 626 µSv/a in the Tata Pani, Gilgit and 34.7 µSv/a in the Garam Chashma, Chitral. Results revealed that hot springs water in the Tata Pani, Gilgit had surpassed the threshold limit (100 µSv/a) set by the World Health Organization (WHO). This study concluded that hot springs water should be avoided for drinking and other domestic uses.


Asunto(s)
Agua Potable , Manantiales de Aguas Termales , Monitoreo de Radiación , Radón , Contaminantes Radiactivos del Agua , Ingestión de Líquidos , Agua Potable/análisis , Humanos , Pakistán , Radón/análisis , Estados Unidos , Contaminantes Radiactivos del Agua/análisis
16.
J Environ Manage ; 301: 113835, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34600421

RESUMEN

Mining of uranium for defense-related purposes has left a substantial legacy of pollution that threatens human and environmental health. Contaminated waters in the arid southwest are of particular concern, as water resource demand and water scarcity issues become more pronounced. The development of remediation strategies to treat uranium impacted waters will become increasingly vital to meet future water needs. Ion flotation is one technology with the potential to address legacy uranium contamination. The green biosurfactant rhamnolipid has been shown to bind uranium and act as an effective collector in ion flotation. In this study, uranium contaminated groundwater (∼440 µg L-1 U) from the Monument Valley processing site in northeast Arizona was used as a model solution to test the uranium removal efficacy of ion flotation with biosynthetic (bio-mRL) and three synthetic monorhamnolipids with varying hydrophobic chain lengths: Rha-C10-C10, Rha-C12-C12, and Rha-C14-C14. At the groundwater's native pH 8, and at an adjusted pH 7, no uranium was removed from solution by any collector. However, at pH 6.5 bio-mRL and Rha-C10-C10 removed 239.2 µg L-1 and 242.4 µg L-1 of uranium, respectively. By further decreasing the pH to 5.5, bio-mRL was able to reduce the uranium concentration to near or below the Environmental Protection Agency maximum contaminant level of 30 µg L-1. For the Rha-C12-C12 and Rha-C14-C14 collector ligands, decreasing the pH to 7 or below reduced the foam stability and quantity, such that these collectors were not suitable for treating this groundwater. To contextualize the results, a geochemical analysis of the groundwater was conducted, and a consideration of uranium speciation is described. Based on this study, the efficacy of monorhamnolipid-based ion flotation in real world groundwater has been demonstrated with suitable solution conditions and collectors identified.


Asunto(s)
Agua Subterránea , Uranio , Contaminantes Radiactivos del Agua , Contaminación Ambiental , Humanos , Minería , Uranio/análisis , Contaminantes Radiactivos del Agua/análisis
17.
Talanta ; 239: 123141, 2022 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-34920262

RESUMEN

Since daily drinking water is one of the major source for the ingestion of radiotoxic 222Rn and 226Ra, the demand for a simple method to determine these two radionuclides has significantly increased. In the present study, a rapid, simple sequential analysis method for determining 222Rn and 226Ra in drinking water using a liquid scintillation counter was developed. The method employs solvent extraction and correction equations for the effect of native 222Rn for 226Ra analysis. Validation and examination of applicability for drinking water analysis were conducted using 222Rn-injected water and 226Ra standard source. Minimum required counting times for examining drinking water on Quantulus 1220 and Hidex 300SL were estimated via minimum detectable activity depending on the counting time. In addition, the correction method, including an equation for reducing analysis time by more than 10 days, was suggested based on the analytical results for different elapsed times between sampling and measurement.


Asunto(s)
Agua Potable , Monitoreo de Radiación , Radio (Elemento) , Contaminantes Radiactivos del Agua , Radio (Elemento)/análisis , Conteo por Cintilación , Contaminantes Radiactivos del Agua/análisis , Abastecimiento de Agua
18.
J Environ Radioact ; 240: 106759, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34700123

RESUMEN

After the Fukushima Dai-ichi nuclear power plant accident in March 2011, the fluvial discharge of 137Cs from watersheds to rivers was analyzed between 2011 and 2021. The concentrations of dissolved and particulate 137Cs were measured in river water samples collected from two rivers (the Hiso and Wariki rivers, mainly draining farmlands and forests, respectively) draining approximately 4-7 km2 watersheds in a montane area (the areal deposition of 134+137Cs; 1-3 MBq·m-2 in March 2011) of Iitate Village, Fukushima. Over the 10 yr analysis, the particulate 137Cs concentrations in the Hiso and Wariki rivers decreased by 70 and 50 times, respectively, and that of the dissolved form decreased by 150 and 130 times, respectively. Moreover, the apparent Kd (distribution coefficient) of 137Cs for water samples from both rivers have increased gradually over these periods. In 2011, the 137Cs discharge rates through the Hiso and Wariki rivers were 0.63% and 0.46% per year of the total amount of 137Cs deposited in their catchments, respectively; however, by 2021, these rates had decreased to 0.09% and 0.03% per year. The cumulative 137Cs discharge rates over 10 yr in the farmland- and forest-dominated rivers were 1.95% and 1.33%, respectively. These rates of the farmland-dominated river were ∼1.4-fold greater than those of the forest-dominated river. Moreover, ∼90% of the of the discharge occurred in particulate form while the remaining ∼10% was in the dissolved form. Thus, 137Cs deposited within these watersheds due to the accident was gradually discharged by the rivers over the 10-yr period; however, the majority remains stored in soils and litters etc. of the catchment area. These results indicate that 137Cs outflow from land-to-ocean will be limited in the future, as the river export of 137Cs is expected to continue decreasing.


Asunto(s)
Accidente Nuclear de Fukushima , Monitoreo de Radiación , Contaminantes Radiactivos del Suelo , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Japón , Plantas de Energía Nuclear , Ríos , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis
19.
Radiat Prot Dosimetry ; 196(3-4): 241-247, 2021 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-34718798

RESUMEN

Scintillation-detector-based SMART RnDuo (AQTEK System, India) and LED fluorimeter (Quantalase Instrument, India) were used for measurements of radon and uranium concentration in 54 groundwater samples collected from different locations in the Palwal district of Haryana (India). Radon in 26% and uranium in 54% of samples were found to be at higher levels than the maximum contamination limit (11 Bq l-1) for drinking water recommended by US Environmental Protection Agency and provisional guideline level (30 µg l-1) stated by World Health Organization.


Asunto(s)
Agua Potable , Agua Subterránea , Monitoreo de Radiación , Radón , Uranio , Contaminantes Radiactivos del Agua , India , Radón/análisis , Uranio/análisis , Contaminantes Radiactivos del Agua/análisis
20.
J Environ Radioact ; 240: 106753, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34619634

RESUMEN

The partitioning coefficient, Kd, which is defined by the reversible sorption processes between a solid and an aqueous phase at equilibrium, is one of the most important parameters to assess environmental transport and risk. In this study, a series of simple laboratory experiments were conducted to investigate sorption properties of 134Cs on a model sediment under two treatments (shaken vs non-shaken) and with three (small: <75 µm, large: > 75 µm and bulk i.e., composite) particle size fractions. Vertical transport of 134Cs across the water-sediment interface and into sediment was also evaluated. As expected, grain size had the strongest influence on 134Cs Kd values, with the small particle size fraction yielding significantly higher Kd values than the large and bulk fractions. The mean Kd values obtained from the various experiments ranged from 89 ± 13-130 ± 5 L kg-1 (small), 44 ± 10-91 ± 13 L kg-1 (large), 73 ± 3-112 ± 11 L kg-1 (bulk, shaken) and 73 ± 5-110 ± 4 L kg-1 (bulk, non-shaken). Most of the 134Cs partitioning processes occurred rapidly (<2 h) into the experiment. Physical mixing (shaken) did not appear to significantly affect the 134Cs Kd values. In complement, a separate experiment on the vertical penetration of 134Cs into a bulk sediment column showed that 134Cs was able to penetrate up to 5 cm into the sediment column after 88 days (∼0.6 mm d-1) and this flux rate is comparable to natural settings. Adsorption and contact time were found to be key for the 134Cs penetration process. Results from these experiments add to the literature on post-event radionuclide transport studies in marine settings and provide an experimental perspective that can be built upon to complement field observations.


Asunto(s)
Monitoreo de Radiación , Contaminantes Radiactivos del Suelo , Contaminantes Radiactivos del Agua , Adsorción , Radioisótopos de Cesio/análisis , Sedimentos Geológicos , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...