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1.
J Environ Radioact ; 226: 106354, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33046265

RESUMO

Tritium, the radioactive isotope of hydrogen, has been used to understand groundwater recharge processes for decades. The current variation of tritium in the atmosphere is largely attributed to stratospheric production and fall out rates as well as global circulation phenomena controlling the hydrological cycle. Global controls on the variability in atmospheric tritium activity are poorly suited to explain local variation and tritium activities in precipitation are often assumed to be uniform over both local and regional catchments and watersheds. This assumption can result in both over and under estimation of modern recharge within an aquifer when using tritium as the recharge proxy. In order to minimize the inherent prediction residuals associated with tritium based recharge investigations, the variability of tritium in precipitation was modelled from 127 spatial precipitation samples taken over a two year period, combined with a 76 precipitation sample group-set taken over a one year period in a single location. Precipitation events were traced backward in time, from the point of collection, using HYSPLIT modelling to ascertain the origins of moisture content as well as the altitudes of moisture origin reached along the particle track. Tritium activities, collected over a one year period in Paarl, range from 0.45 to 4.16 TU and have a mean of 1.59 TU. Spatial storm events in the Western Cape in 2017 and 2018 had a range from 0 to 2.2 and 0.37 to 3.27 TU, respectively, with mean activities of 1.18 (n = 34) and 1.25 TU (n = 32). Both storm events had similar tritium variability (σ = 0.5 n = 35 and 0.48 n = 32). Regional precipitation events had the largest range of tritium activities (0.55-12.2 TU). Although not all tritium activities can be explained by interrogating the water mass origin, this study suggests that approximately 90% of events can be completely or partially attributed to the origin of the water mass. The variability of tritium, both spatially and temporally, was higher than expected, confirming that when uniform tritium inputs are used, the groundwater system would provide inaccurate modern recharge estimates. Higher spatial resolution of tritium variation in precipitation for a particular region will improve our ability to relate tritium activities in groundwater to local precipitation.


Assuntos
Monitoramento de Radiação , Trítio/análise , Água Subterrânea , Hidrologia , África do Sul
2.
J Environ Radioact ; 222: 106346, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892903

RESUMO

Early observations of the tritium (3H) activity in precipitation from Switzerland started in 1967 in Bern and a monitoring program with improved analytical techniques was carried out between 1971 and 2009. Between 2012 and 2015, we performed tritium analyses on daily precipitation samples from north-western Switzerland to better constrain the tritium variability. We also collected waters dripping inside Milandre Cave (Jura Mountains) with a 4-6 months' resolution in order to estimate the age of the drip water, which is mandatory to interpret the high-resolution speleothem (cave carbonate deposits) records. Over the monitoring period, the mean tritium concentration in the daily precipitation samples was approximately 8.7 ± 4.7 TU with distinct seasonality showing higher values in spring and summer (from April-May to August-September). The similarity in trends with the other cosmogenic radionuclide beryllium-7 (7Be) suggests that, for the study site, tritium in precipitation essentially originates from stratospheric input in spring. In winter, precipitation dynamics with increasing moisture originating from the Atlantic and diluted during transport contribute to low values close to the Atlantic background. In cave drip water, the depleted activity level of tritium indicates a relatively long percolation time from the surface to the cave of several years. A residual superimposed short tritium variability provides evidence for the occurrence of fast flowing water paths. The contribution from both components were quantified based on a two-component lumped parameter-mixing model. Finally, we show that tritium concentrations in cave drip water are linked to the moisture origin and atmospheric transport pathways.


Assuntos
Berílio , Monitoramento de Radiação , Radioisótopos , Trítio , Berílio/análise , Cavernas , Radioisótopos/análise , Suíça , Fatores de Tempo , Trítio/análise
3.
J Environ Radioact ; 223-224: 106370, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32883536

RESUMO

Tritium is a radioisotope of hydrogen with a half-life of 12.32 years and was used for its luminescent properties by the watchmaking industry from 1962 to the 2008. Tritiated luminescent salts were integrated in the paints applied on the index and dial of watches and clocks. French and Swiss watchmaking workshops used more than 28 000 TBq of tritium over this period of time and produced almost 350 million watches. Despite the end of tritiated salts use in watchmaking workshops in 1992 in France and 2008 in Switzerland, high level of organically bound tritium (OBT) are still observed in sediments of the Rhône River downstream the Lake Geneva. Contamination of the Rhône River by tritiated hot particles since 1962 up to nowadays remains poorly documented. In order to assess the long term behavior and fate of technogenic tritium in this river and its trajectories in the river system, two sediment cores were collected at the upstream (UC) and downstream (DC) part of the Rhône River in France and OBT contents were determined. For both sedimentary cores, maximum OBT contents were registered over the 1980s when tritium was intensively used by watchmaking industries. These residual OBT contents are 1 000 to 10 000 fold higher than current natural background levels in riverine sediments. The OBT contents progressively decreased since 1989 with close effective half-life in upstream and downstream area (5 ± 2 years). The OBT contents were lower in DC than in UC due to the dilution by uncontaminated sediments delivered by tributaries not affected by the watchmaking industries. Trajectories analysis indicates that the resiliency of the Rhône River system in regards to this contamination would be reached in 14-70 years and in 14-28 years respectively for the upstream and downstream part of the river.


Assuntos
Monitoramento de Radiação , França , Rios , Suíça , Trítio/análise , Poluentes Radioativos da Água/análise
4.
J Environ Radioact ; 218: 106238, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32421572

RESUMO

The western North Pacific is one of the most studied oceanic basins due to its diverse structure and important role in connection with the adjacent reservoirs. Tritium (3H) and radiocarbon (14C) have been frequently exploited as oceanographic tracers due to their suitable properties; several extensive observation projects, such as GEOSECS, WOCE and WOMARS, used these two radionuclides to investigate different oceanographic processes, pathways, ocean currents and time scales of deep and bottom water formation. Here we evaluate temporal changes in 3H and 14C levels in seawater of the western North Pacific Ocean from 1993 to 2012. When compared to the background levels from 1993, the data from 2012 suggests significant impact of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on surface and vertical 3H seawater profiles, increasing its water column inventories in the southern part of the 149°E meridian by a factor of 2-7. On the other hand, 14C content in surface seawater has been steadily decreasing from 1993, with the accelerated rate from 2005, probably due to downwelling of bomb-produced radiocarbon and its transport along isopycnal layers. The influence of the Oyashio current on 14C levels in the northern part of the investigated transect and formation of its intrusion was also clearly visible in the collected datasets. Regarding bomb-produced radiocarbon, its water column inventories decreased or remained same from 2005 to 2012 at all stations, except the ones located in the coastal areas of the New Guinea island (3.5°S).


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Trítio/análise , Poluentes Radioativos da Água , Radioisótopos de Césio , Japão , Oceanos e Mares , Oceano Pacífico , Água do Mar
5.
J Environ Radioact ; 218: 106261, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32421581

RESUMO

Tritium is a radionuclide commonly observed worldwide in riverine systems. In the Rhône River downstream the Lake Geneva (Switzerland and France), its occurrence is also related to its use for its luminescent properties in watchmaking paints. In fact, tritium is regularly observed at anomalous levels in this river and extreme events such as flushing operations might conduct to its transport downstream. In the Rhône River, characterized by 21 dams downstream the Geneva Lake, such operations are regularly organized to remove the sediments and limit problematic consequences such as siltation and increased flooding hazards. The consequences of dam flushing operations on tritium concentrations were thus investigated. Samples of Suspended Particulate Matter (SPM) and water were collected in the Rhone River downstream of Geneva in June 2012, during a planned flushing operation of three upstream reservoirs (Verbois, Chancy-Pougny and Génissiat). The concentrations of tritiated water (HTO) and organically bound Tritium (OBT) were measured and compared to reference concentrations. The flushing operations had no impact on the HTO concentration while the increases observed were related to the authorized releases of HTO from a nuclear power plant located downstream the dams. High increases of OBT concentrations in SPM were observed at two stations (Creys-Malville and Jons) without clear spatial or temporal trends. These anomalous peaks could be explained by the heterogeneous spatial distribution of technogenic tritium leading to large variations of tritium concentrations within the samples even though collected in areas close to each other. The results highlight the need to investigate the amount of such technogenic tritium currently stored in the upstream Rhone River as it might be significant.


Assuntos
Monitoramento de Radiação , Trítio/análise , Poluentes Radioativos da Água/análise , França , Centrais Elétricas , Rios , Suíça
6.
Arch Environ Contam Toxicol ; 79(1): 131-146, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32285161

RESUMO

Former nuclear weapons material production at the U.S. Department of Energy's Savannah River Site (SRS) has resulted in contamination of certain terrestrial and aquatic ecosystems on site with legacy wastes such as radiocesium (137Cs), tritium (3H), and metals. We collected fish and invertebrates from five beaver ponds (sites) above, adjacent, and downgradient of three SRS facilities (H-, F-, and C-Areas) to evaluate whether the accumulation of metals and radionuclides in biota were associated with specific facility operations and if the measured levels could pose risks to aquatic organisms. We compared concentrations of various metals, 137Cs, and 3H in fish, as well as in water (3H only), among sites along the stream gradient. Fish collected from sites adjacent to H-Area had significantly higher 137Cs concentrations compared to fish from other sites. Both biota and water samples indicated significantly greater levels of 3H in sites adjacent to and downstream of C-Area. Concentrations of zinc (Zn), copper (Cu), and mercury (Hg) in some samples exceeded effects levels reported for fish and may pose a risk to fish populations. This study reported fish tissue concentrations of 137Cs and 3H, which have not been documented extensively in ecotoxicological studies. Our results suggested that industrial operations such as nuclear material production at SRS could have long-lasting impact on the aquatic ecosystem via the release of radionuclides and metals, and long-term monitoring of physiological effects and population level impact in biota exposed to these contaminants are recommended.


Assuntos
Organismos Aquáticos/química , Armas Nucleares , Monitoramento de Radiação/métodos , Rios/química , Poluentes Radioativos da Água/análise , Animais , Organismos Aquáticos/efeitos dos fármacos , Radioisótopos de Césio/análise , Peixes/metabolismo , Invertebrados/química , Invertebrados/efeitos dos fármacos , Metais Pesados/análise , Tanques/química , South Carolina , Trítio/análise
7.
Chemosphere ; 249: 126114, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32044611

RESUMO

Monitoring drinking water, including bottled water, is imperative to safeguarding public health especially where bottled water consumption is high like in the United Arab Emirates (UAE). In this study, radionuclide activity levels of Tritium (3H) and Potassium (40K) were assessed in various brands of bottled water marketed in UAE. Activity level data was used to calculate the annual effective doses (Ed) for different age groups, and the excess lifetime cancer risk (ELCR) for adult males and females in the UAE population. Activity levels for both radionuclides were below the allowable maximum guideline values specified by local and international standards. Calculated total age dependent ingestion doses revealed that adults and lactation age groups received the highest effective ingestion doses. Adult males exhibited a higher ELCR for both isotopes, compared to females. Nonetheless, total radioactive dose for each water brand (0.91-1.47 µSv/yr) as well as for each population group were well below the recommended annual reference dose level of 100 µSv set by World Health Organization. Therefore, bottled water in the UAE is safe from the radiological aspect for investigated radionuclides, and poses no significant radiological exposure and health risk to the public.


Assuntos
Água Potável/análise , Radioisótopos de Potássio/análise , Trítio/análise , Poluentes Radioativos da Água/análise , Adulto , Exposição Dietética , Ingestão de Alimentos , Feminino , Humanos , Masculino , Radioisótopos/análise , Medição de Risco/métodos , Emirados Árabes Unidos
8.
Isotopes Environ Health Stud ; 56(2): 193-204, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32000521

RESUMO

Water samples from the different basins of the Baltic Sea and North Sea were collected during four cruises taken place in 2016-2017. Altogether 60 water samples for 3H activity concentration and 120 water samples for stable isotopes ratio (δ18O and δ2H) were analysed. Exceptionally strong inflow activity from North Sea to the Baltic Sea occurred prior our surveys. The data obtained enabled comprehensive evaluation of tritium and stable isotopes distribution in waters of Baltic Sea and contributing inputs, including riverine and atmospheric freshwater flux and saline water inflow through the Danish Straits. By comparing with the previous studies, we noticed a tendency toward an increase in the δ18O and δ2H values of zero-salinity component over time, which may be due to climate change. In the case of tritium, the influence of artificial sources has also been noticed.


Assuntos
Deutério/análise , Monitoramento Ambiental/métodos , Isótopos de Oxigênio/análise , Água do Mar/química , Trítio/análise , Mudança Climática , Estônia , Água Doce/química , Lituânia , Mar do Norte , Oceanos e Mares , Federação Russa , Salinidade
9.
J Environ Radioact ; 216: 106177, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32063550

RESUMO

The method of tritium activity measurements by electrolytic enrichment in combination with liquid scintillation counting is well known for many years. In the Water Research Institute in Bratislava was this system employed since the 60-ties of the 20th century. In 2018 the laboratory of radiochemistry of Water Research Institute obtained a new electrolytic enrichment system with higher enrichment factor (varying from 9 to 22, depending on the total ampere-hours used). The enrichment factor of the previous system was about 6. Complementary to the new system, also the new LCS counter Quantulus GCT 6220 was added. This spectrometer has active background suppression function (Guard Compensation Technology - GCT) and for the tritium measurement the background counts decreased from cca. 9 cpm (for Tricarb 2900 TR) to approximately 1 cpm. To demonstrate the capabilities of this system, we present results of the tritium concentration in precipitations during the period from May 2016 to May 2019. The seasonal variations of tritium activities in precipitation are observed, with maximum values in spring season and minimum in winter. Additionally, selected tritium activities from the extensive monitoring of river waters in Slovakia are presented.


Assuntos
Trítio/análise , Academias e Institutos , Monitoramento de Radiação , Contagem de Cintilação , Eslováquia , Água , Poluentes Radioativos da Água
10.
Isotopes Environ Health Stud ; 56(2): 158-169, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31957484

RESUMO

Karst environments have an inherent complexity that interferes with their hydrogeology comprehension. Hence, isotope hydrology can be a valuable tool to assess trajectory of subsurface flows in an unexplored setting. The study area is located in the Lagoa Santa Karst, an environmental protection area of great economic, cultural and ecological importance, where Neoproterozoic metalimestones accommodate karst-fractured aquifers, characterized by complex water dynamics, essential vulnerability and high productivity. The purpose of this study was to investigate groundwater flow origins of springs using principally environmental stable isotopes 2H and 18O. Rainwater and spring water were sampled and analysed. The LMWL presents angular and linear coefficients strongly similar to those of the GMWL. Spring isotopic signatures, which represent the base flow and present wide-ranging of 2H and 18O, were separated into two groups. The first group can be associated with recent rainwater major contributions, while the second group shows significant evaporated water contributions, largely represented by resurgences. Tritium concentration and physico-chemical parameter data supported this interpretation, pointing that waters of the second group remained more time on the surface and subsurface. Therefore, using isotope tracers to evaluate upper groundwater zone in this tropical karst system is a powerful instrument for water resources management.


Assuntos
Deutério/análise , Monitoramento Ambiental/métodos , Água Subterrânea/química , Nascentes Naturais/química , Isótopos de Oxigênio/análise , Brasil , Hidrologia , Trítio/análise , Recursos Hídricos
11.
Chemosphere ; 238: 124646, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31473523

RESUMO

Humic substances (HS) in the aqueous solutions can be considered as colloidal particles formed by amphiphilic units. HS form micelles-like structures at concentrations close to 5 g/L. However colloidal behavior of HS at concentrations below 100 mg/L is unknown. Using radiotracer assay we have shown that in this concentration range HS form rare adsorption layers at the liquid/liquid interface and penetrate into the organic phase with the distribution ratio close to 10-3. We found that pH and HS molecular weight strongly influence on the distribution ratio but do not significantly change the adsorption. Furthermore, colloidal properties of HS are strongly depending on its origin: the highest surface activity was shown for HS separated from peat and the least was observed for HS separated from soils. We anticipate our assay to be a helpful tool for detailed analysis and modeling HS and humic-like materials colloidal behavior in the environment.


Assuntos
Substâncias Húmicas/análise , Soluções/química , Adsorção , Coloides , Concentração de Íons de Hidrogênio , Micelas , Peso Molecular , Solo , Trítio/análise
12.
Drug Test Anal ; 12(1): 101-108, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31486294

RESUMO

The small molecule, stemazole, has significant therapeutic effects on neurodegenerative diseases, such as Alzheimer's disease (AD), due to its neuroprotective effects and remarkable survival-promoting activity in stem cells. However, pharmacokinetic properties of stemazole were unclear. In this study, a rapid and effective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to detect stemazole. The detector was operated in the positive-ion mode with an electrospray ionization (ESI) interface in multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an Acquity UPLC® BEH C18 column with gradient elution. Stemazole was extracted from plasma following a one-step protein precipitation method. The method was fully validated for its selectivity, specificity, and sensitivity. The calibration curve range of 5-1125 ng/mL showed good linearity for stemazole. Intra-day and inter-day precision rates were less than 10%, and accuracy ranged from 95.87% to 105.23%. The pharmacokinetic profiles were illustrated through the newly developed method for the first time. The absolute oral bioavailability of stemazole is 32.10%. Therefore, it is feasible as an oral medication, which greatly facilitates its broad application. The biological distribution of tritium-labeled stemazole in mice was studied, and the results showed that stemazole was absorbed rapidly and distributed widely, mainly in the liver and kidneys. A specific amount was also detected in the brain, which provides a prerequisite for the use of stemazole to treat neurodegenerative diseases. This work represents first description of the pharmacokinetics, bioavailability, and tissue distribution of stemazole and will lay the foundation for further investigation and drug development.


Assuntos
Hidrazinas/farmacocinética , Oxidiazóis/farmacocinética , Administração Oral , Animais , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Hidrazinas/administração & dosagem , Hidrazinas/sangue , Masculino , Camundongos , Oxidiazóis/administração & dosagem , Oxidiazóis/sangue , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem , Distribuição Tecidual , Trítio/análise
13.
Artigo em Inglês | MEDLINE | ID: mdl-31614963

RESUMO

The deuterium plasma experiment was started using the Large Helical Device (LHD) at the National Institute for Fusion Science (NIFS) in March 2017 to investigate high-temperature plasma physics and the hydrogen isotope effects towards the realization of fusion energy. In order to clarify any experimental impacts on precipitation, precipitation has been collected at the NIFS site since November 2013 as a means to assess the relationship between isotope composition and chemical species in precipitation containing tritium. The tritium concentration ranged from 0.10 to 0.61 Bq L-1 and was high in spring and low in summer. The stable isotope composition and the chemical species were unchanged before and after the deuterium plasma experiment. Additionally, the tritium concentration after starting the deuterium plasma experiment was within three sigma of the average tritium concentration before the deuterium plasma experiment. These results suggested that there was no impact by tritium on the environment surrounding the fusion test facility.


Assuntos
Deutério/análise , Centrais Nucleares , Chuva/química , Trítio/análise , Japão , Estações do Ano
14.
Radiat Prot Dosimetry ; 184(3-4): 338-341, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31329995

RESUMO

Monthly precipitation samples have been collected at Toki, Japan, from November 2013 to March 2017. In this report, selected data were analysed to identify the regional hydrogen and oxygen isotope compositions. Tritium (3H) concentration in the precipitation ranged from 0.10 to 0.61 Bq L-1 and higher 3H concentrations were observed in spring rather than in other seasons. This range was similar to values reported in Chiba City, Japan. 3H concentration and the ratio d-excess, and δD values were roughly clustered according to each separate season. These regional hydrogen and oxygen isotope compositions will be used for environmental assessments of effects of the deuterium plasma experiments of the large fusion test device.


Assuntos
Hidrogênio/análise , Isótopos de Oxigênio/análise , Monitoramento de Radiação/métodos , Contagem de Cintilação/instrumentação , Trítio/análise , Poluentes Radioativos da Água/análise
15.
J Environ Radioact ; 208-209: 105999, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31271849

RESUMO

Canadian Nuclear Laboratories (CNL)'s Chalk River Laboratories (CRL) site is home to a large nuclear research complex in Canada. CRL's air tritium releases amount to about 1015 Bq/year. The objective of the study was to characterize the spatial footprint of the 60 years of tritium atmospheric releases in surface soil by measurement of organically bound tritium (OBT). Soil OBT activity concentrations were of particular interest because soil represents a long-term tritium reservoir that can act as a historical record of tritium releases into the environment. Soil samples to a 5 cm depth were collected within the CRL site from 2012 to 2014. Each sample was analyzed for tritiated water (HTO) and OBT activity concentrations. The highest HTO and OBT measurements obtained during this study were 154.0 ±â€¯7.8 Bq/L and 180.9 ±â€¯37.3 Bq/L, respectively. A developed OBT map indicated that retained tritium in soil was not related to the distance of sources-term but it was related to the prevailing wind direction.


Assuntos
Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Solo/química , Trítio/análise , Canadá , Rios
16.
Radiat Prot Dosimetry ; 184(3-4): 334-337, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31251365

RESUMO

To obtain a better understanding of recent tritium concentration and its seasonal cycle in Japan, monthly precipitation samples were collected in Hokkaido, Gifu and Okinawa prefectures from June 2014 to December 2017. The arithmetic mean ( ± standard deviation) of tritium concentrations in precipitation samples from Hokkaido, Gifu and Okinawa were estimated to be 0.62 ± 0.27 Bq L-1, 0.32 ± 0.12 Bq L-1 and 0.13 ± 0.05 Bq L-1, respectively. These results indicate that the concentrations increase with latitude. In addition, the highest and the lowest concentrations appeared in spring and summer, respectively. To clarify the origins and sources of these cycles, further analyses of chemical compositions of precipitation and meteorological conditions are needed.


Assuntos
Poluentes Radioativos do Ar/análise , Radiação de Fundo , Monitoramento de Radiação/métodos , Trítio/análise , Humanos , Japão , Estações do Ano
17.
Environ Sci Process Impacts ; 21(6): 938-949, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31179456

RESUMO

The speciation of radioactive tritium (T) in a naturally-established subtropical loblolly pine forest that has been irrigated with highly-contaminated pond water for the last 20 years is reported. This irrigation project was created to limit the underground transport of a tritium-rich plume which also contains low levels of toxic organics, metals and radionuclides such as carbon-14 (14C) from a nearby low-level waste burial ground. The levels of tritiated water (HTO) in the wood cores were not influenced by recent irrigation activities. However, the tritium levels in the last 20 years of tree growth were more than 3-fold higher than that of tritium in the older growth. This was due to recent irrigation with organic-bound tritium (OBT)-rich water and subsequent accumulation of high levels tritium as OBT relative to tissue HTO. High levels of pond irrigation water OBT resulted from biogenic processes that converted HTO to OBT. Data for 14C that were acquired for some of the forest materials indicated that the processes controlling the movement and accumulation of 14C in this system are somewhat different than that of tritium. Spectroscopic characterization of tree core tissue of <20 years in age found no explanation for the unusually wide dark growth rings. It was concluded that the trees were over-irrigated based on results from other published studies with wood from severely-flooded areas. Although HTO is indeed toxic to biota, OBT represents a relatively greater hazard to biota because it can be bioaccumulated and retained for long periods of time in living tissues.


Assuntos
Pinus/química , Poluentes Radioativos/análise , Trítio/análise , Madeira/química , Radioisótopos de Carbono/análise , Florestas , Monitoramento de Radiação , Poluentes Radioativos/química , Resíduos Radioativos , Trítio/química , Gerenciamento de Resíduos/métodos , Água
18.
Health Phys ; 117(4): 443-448, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31211754

RESUMO

Tritium that is released from nuclear facilities, especially from nuclear reactor units, may be the main origination of tritium in the environment. Atmospheric tritiated water (HTO) is the main chemical form of tritium that is released from nuclear reactor units. HTO in the air, drinking water and foods should be monitored routinely to protect public from the radiological hazards of tritium. Here, concentrations of HTO in the air, drinking water and foods in the vicinity of Qinshan Nuclear Power (QNP) base were measured from 2012 to 2016. And based on the concentrations of HTO measured, annual dose equivalent and collective dose equivalent for adults were calculated to evaluate the radiological hazards derived from HTO. The annual dose equivalent for adults in Qinshan and Wuyuan communities were both far below the dose limit for public exposure, and both showed an increasing trend, indicating that great attention still should be payed to the releasing of tritium from nuclear reactor units in the QNP base.


Assuntos
Poluentes Radioativos do Ar/análise , Exposição Ambiental/análise , Contaminação Radioativa de Alimentos/análise , Reatores Nucleares , Monitoramento de Radiação/métodos , Trítio/análise , Poluentes Radioativos da Água/análise , Adulto , Humanos , Doses de Radiação
19.
Artigo em Inglês | MEDLINE | ID: mdl-31151262

RESUMO

Artificial underground reservoirs have changed the hydrological cycle from its natural condition. This modification may trigger a series of negative environmental effects both at the local and regional levels. This study investigated the impact of the Wanghe artificial underground reservoir on groundwater flow and quality in the reservoir and its downstream area. Wanghe is a typical artificial underground reservoir scheme in China, which assumes the dual function of fresh-water preservation and control of seawater intrusion. The groundwater flow pattern has changed after the reservoir construction, and the water level in the reservoir rose rapidly. Evaluation of long-term groundwater level fluctuation suggested that the reservoir deprived the downstream aquifer of the runoff, which it received under the natural flow regime. A preliminary isotopic evaluation using 3H was developed to understand the groundwater flow and renewal rates in the study area. The uniform distribution of tritium levels in the reservoir indicated that the stored water was well-mixed in both horizontal and vertical directions. The intervention on groundwater circulation also made differences in groundwater renewal rates between stored and downstream water. Field investigations on groundwater nitrogen pollution showed that the construction of the artificial underground reservoir resulted in nitrate accumulation in the stored water. Agriculturally derived nitrate was the largest contributor, and NO 3 - concentration varied considerably over time due to fertilization and irrigation activities, rainfall, and denitrification. NO 3 - -N distributed homogeneously in the reservoir, which was attributed to the construction of the subsurface dam, land use pattern and artificial groundwater flow.


Assuntos
Água Subterrânea/análise , Poluentes Químicos da Água/análise , Abastecimento de Água , Agricultura , China , Monitoramento Ambiental , Hidrologia , Nitratos/análise , Nitrogênio/análise , Trítio/análise
20.
J Environ Radioact ; 208-209: 105997, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31229735

RESUMO

A survey of eastern Canadian biota was conducted to determine the distribution of activity concentrations of organically bound tritium (OBT). Fish samples were collected from Lake Ontario and the St. Lawrence River in areas continuously receiving inputs of tritiated water (HTO) from operating nuclear power plants, and from Lake Nipissing, a background area. Components of their aquatic environments were sampled. The data collected also provides some insight on how tritium activity concentrations in ambient water influence tissue free water tritium (TFWT) and OBT activity concentrations in biological tissues. Using an ALOKA liquid scintillation system, fish TFWT and OBT were quantified. Fish TFWT averaged 1.6 ±â€¯0.1 Bq/L in Lake Nipissing and 3.1 ±â€¯0.3 Bq/L in Lake Ontario. In contrast, TFWT ranged from 11.1 to 80.8 Bq/L in the St. Lawrence River near the Gentilly-2 Canada Deuterium Uranium (CANDU) site. Fish tissue OBT levels were 4.0 ±â€¯0.4 Bq/L and 5.3 ±â€¯0.2 Bq/L for Lake Nipissing and Lake Ontario, respectively, and between 18.1 and 134.2 Bq/L for CANDU sites. The activity concentrations of TFWT and OBT were reviewed for algae, freshwater mussel and various fish samples collected near Gentilly-2, Pickering and Darlington Nuclear Power Generating Stations. TFWT in aquatic biota was found to correlate with the tritium activity concentrations measured in waters at the time of sampling (TFWT/HTO of ambient water was 0.3-4.3). The OBT concentration factors (OBT/HTO of ambient water) were found to be higher in freshwater mussels (between 17 and 47) compared to algae and fish (0.3-10). These results point to a heterogeneous distribution of biota OBT content in these aquatic ecosystems. It was also noted that all fish and algae samples were found to be within the range of tritium activity concentrations that has been historically measured in the same waters. Values in freshwater mussels were above this range.


Assuntos
Organismos Aquáticos/química , Monitoramento de Radiação , Trítio/análise , Poluentes Radioativos da Água/análise , Biota , Ecossistema , Ontário
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