3H Concentrations Research Articles

Radioactivity monitoring in environmental water and air around QNPP

Results of environmental radioactivity monitoring around Qinshan Nuclear Power Plant (QNPP) are reported in this paper. From 1992 to 2005, concentrations of 90Sr, 137Cs and 3H in terrestrial freshwater are (4.4±1.7) mBq•L −1, (0.3±0.1) mBq•L −1 and (1.6±0.5) Bq•L −1, respectively, and (2.8±2.4) Bq•L −1 of 3H in rainwater. Concentrations of 90Sr, 137Cs and 3H in the seawater samples collected from sea area nearby QNPP are (5.4±4.1) mBq•L −1, (0.7±0.2) mBq•L −1 and (1.0±0.5) Bq•L −1, respectively. Concentrations of 90Sr, 137Cs and 3H in the total waste water discharged from NPP-I are (4.0±1.8) m Bq•L −1, (1.0±0.5) mBq•L −1 and (2.8±2.2) Bq•L −1, respectively, and (1.4±0.4) Bq•L −1 of 3H in seawater sampled from No.1 outlet. Atomspheric 3H concentration in 1993 ∼ 2005 at two monitoring sites is (78.9±96.3) and (64.2±40.2) mBq•m −3, respectively, with an increasing trend after 2003. Atmospheric 14C concentrations at the two sites are in the same levels as the background and data of the reference site.

Magnetic Field Effects on Tritium Release from Neutron-Irradiated Beryllium Pebbles

The effects of temperature, magnetic field (MF), and ionizing radiation on the release of tritium from the Be pebbles irradiated in the BERYLLIUM experiment in 1994 in Petten, The Netherlands (irradiation neutron fluence 1.24 × 1025 m-2, irradiation temperature 780 K, and 3H content 7 appm) were investigated in this study. Simultaneous action of these factors corresponds to the real operating conditions of the blanket of a fusion reactor. The total amount of tritium in a separate pebble, the chemical forms of localized tritium (T0, T2, and T+), and the tritium distribution in the pebble volume were determined by a lyomethod (dissolution). Thermoannealing experiments were performed at a constant temperature of 1123 K for 2 h under the following conditions: separately both in MF (1.7 T) and under fast electron radiation (E = 5 MeV; P = 14 MGy·h-1) as well as under the action of all three factors. Tritium in the Be pebbles is localized for the most part as T2 (85 to 94%). The abundances of T+ (4 to 5%) and T0 (5 to 10%) are little. The tritium distribution in a pebble is not uniform; most of the tritium is localized in the inner part of a pebble. An MF of 1.7 T decreases slightly the fractional release of tritium under the given conditions of thermoannealing (from 30 to 25%), the fast electron radiation increases it (from 30 to 40%), but the simultaneous action of the MF and radiation increases it (from 30 to 54%). The effects observed are explained that the MF and radiation affect the concentration of main diffusing particles T0 in a beryllium matrix.

Verifying the geographical origin of beef: The application of multi-element isotope and trace element analysis

Beef samples originating from the major cattle producing regions of the world (Europe, USA, South America, Australia and New Zealand) have been analysed using IRMS and ICP-MS. C and N isotope composition of the beef defatted dry mass and H and O isotope composition of the corresponding lipid fractions were determined. It was observed that intensive maize and/or C 4 pasture feeding, during cattle production, gave rise to significant differences in the 13C content of beef produced in Brazil and the USA versus British beef fed predominantly on C 3 pasture and fodder. The mean δ 2H‰ and δ 18O‰ values of beef lipid correlated well with the latitude of production regions and the relationship between the H and O isotopic contents were found to parallel the Meteoric Water Line. These findings support the hypothesis that the systematic global variations in the 2H and 18O content of precipitation are transferred through drinking water and feed into beef lipid. Multi-element concentrations determined in the beef were combined with the stable isotope data and submitted to multivariate analysis. Six key variables ( δ 13C‰ (defatted dry mass), Sr, Fe, δ 2H‰ (lipid), Rb and Se) were identified by canonical discriminant analysis as providing the maximum discrimination between beef samples on the basis of the broad geographical areas (Europe, South America and Australasia). It was concluded that the methodology in its current state can be used to provide reliable origin information, but this is dependent upon the countries under investigation.

Radiological characterization of drinking waters in Central Italy

Due to the importance of water in human life, its quality must be strictly controlled; for this purpose, simple and reliable analytical methods must be available. In this study, a monitoring of radioactivity content was performed in tap waters collected in a region of Central Italy to check the compliance with recent European and Italian regulations. Gross alpha and beta activities, 238U, 234U, 226Ra, 222Rn, and 3H concentrations were measured. Gross alpha and beta activities were determined by standard ISO 9696 and ISO 9697; for 226Ra, 222Rn and 3H determination, liquid scintillation was used. 238U and 234U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. The results revealed that the tritium concentration was always lower than 6.75 Bq l − 1 . The concentrations (mBq l − 1 ) of 226Ra, 222Rn, 238U, and 234U ranged from < 1.70 to 15.31, from 0.69 to 20.3, from 0.65 to 48.77, and from 0.78 to 51.50, respectively. 234U/ 238U ratios were higher than 1 in most cases. The results obtained revealed that, in most samples, gross alpha and gross beta were lower than the parameter value indicated in the international regulations. An attempt was also made to find a correlation between these results and the chemical parameters of waters.

The current content of artificial radionuclides in the water of the Tobol–Irtysh river system (from the mouth of the Iset River to the confluence with the Ob River)

Data on content of 90Sr, 137Cs, 239,240Pu and 3H in water of the Tobol–Irtysh part of the Techa–Iset–Tobol–Irtysh–Ob river system (through which the “Mayak” PA radioactive wastes are transported) are presented and discussed. The data were received in 2004–2005 under the ISTC project on radioecological monitoring of the Tobol and Irtysh rivers. Monthly observations of 137Cs, 90Sr and 3H content in water in the area of the Tobol and Irtysh confluence have been conducted starting from May 2004. To obtain information on the investigated river system as a whole, the radioecological survey of the Tobol and Irtysh rivers at the section from the mouth of the Iset River to the confluence with the Ob River was carried out in 2004. It is shown that the impact of “Mayak” PA waste transport by 90Sr is distinctly traced as far as the area of the Irtysh and Ob confluence.

Evidence for terrigenic SF 6 in groundwater from basaltic aquifers, Jeju Island, Korea: Implications for groundwater dating

Measurements of the concentrations of dichlorodifluoromethane (CFC-12), tritium (3H), and sulfur hexafluoride (SF6) in groundwater from basaltic aquifers in Jeju Island, Korea, demonstrate a terrigenic source of SF6. Using a lumped-parameter dispersion model, groundwater was identified as young water (<15 years), old water with negligible CFC-12 and 3H, and binary mixtures of the two. Model calculations using dispersion models and binary mixing based on 3H and CFC-12 concentrations demonstrate a non-atmospheric excess of SF6 relative to CFC-12 and 3H concentrations for more than half of the samples. The non-atmospheric excess SF6 may have originated from terrigenic sources in relict volcanic fluids, which could have acquired SF6 from granites and basement rocks of the island during volcanic activity. Local excess anthropogenic sources of SF6 are unlikely. The SF6 age is biased young relative to the CFC-12 age, typically up to 20 years and as high as 30 years. This age bias is more pronounced in samples of groundwater older than 15 years. The presence of terrigenic SF6 can affect the entire dating range for groundwater in mixtures that contain a fraction of old water.

Constraining the age distribution of highly mixed groundwater using 39Ar: A multiple environmental tracer (3H/3He, 85Kr, 39Ar, and 14C) study in the semiconfined Fontainebleau Sands Aquifer (France)

A multitracer (3H/3He, 85Kr, 39Ar, and 14C) approach is used to investigate the age structure of groundwater in the semiconfined Fontainebleau Sands Aquifer that is located in the shallower part of the Paris Basin (France). The hydrogeological situation, which is characterized by spatially extended recharge, large screen intervals, and possible leakage from deeper aquifers, led us to expect a wide range of residence times and pronounced mixing of different water components. Consequently, a large set of tracers with corresponding dating ranges was adopted. Commonly used tracers for young groundwater (3H, 3He, and 85Kr) can identify only those components with ages below 50 years. This approach is reliable if a large fraction of the water recharge occurs within this period. However, if a considerable fraction is older than 50 years, a tracer that covers intermediate age ranges below 1000 years is needed. We examine the use of 39Ar, a noble gas radioisotope with a half‐life of 269 years, to constrain the age distribution of groundwater in this timescale range. Recharge rate, depth of water table, and the age structure of the groundwater are estimated by inverse modeling. The obtained recharge rates of 100–150 mm/yr are comparable to estimations using hydrograph data. Best agreement between the modeled and measured tracer concentrations was achieved for a thickness of the unsaturated soil zone of 30–40 m, coinciding well with the observed thicknesses of the unsaturated zone in the area. Transport times of water and gas from the soil surface to the water table range between 10 and 40 and 1 and 6 years, respectively. Reconstructed concentrations of 85Kr and 3H at the water table were used for saturated flow modeling. The exponential box model was found to reproduce the field data best. Conceptionally, this finding agrees well with the spatially extended recharge and large screened intervals in the project area. Best fits between model and field results were obtained for mean residence times of 1–129 years. The 39Ar measurements as well as the box model approach indicate the presence of older waters (3H and 85Kr free). Using 39Ar to date this old component resulted in residence times of the old water components on the order of about 100–400 years. The 14C measurements provide additional evidence for the correctness of the proposed age structure.

A time series of environmental tracer data from deep meromictic Lake Lugano, Switzerland

An 11‐yr (1990–2001) time series of tritium‐helium‐3 (3H‐3He) apparent water ages as well as one sulfur hexafluoride (SF6) profile were used to study the development of the vertical mixing dynamics of the deep, meromictic northern basin of Lake Lugano. The density stratification of the water column was dominated by an increase in dissolved ions with depth, which remained approximately constant during the 1990s. The deep‐water temperature increased steadily during this period, passing a threshold above which cooling of the surface water could force convection. However, increasingly mild winter temperatures prevented the occurrence of a turnover until 2005. The maximum apparent 3H‐3He water age increased from about 16 yr in 1990 to 23 yr in 2001. The maximum apparent SF6 age in 2001 was 12.8 yr. The large difference between the apparent 3H‐3He and SF6 ages is at least partly due to nonlinear effects of mixing, causing SF6 ages to underestimate the true mean deep‐water residence time, whereas 3H‐3He ages overestimate it. The decreasing concentrations of 3H and 3He are more reliable indicators of the continuous deep‐water exchange in the lake than are the apparent ages. Budget calculations using the tracer concentrations reveal an annual renewal of the deep water below 100 m in depth by about 8% and enable the calculation of long‐term mean profiles of the effective vertical turbulent diffusivity Kz. No trend in the mixing intensity during the 1990s could be determined. The radiogenic He flux into the lake is comparable to estimates of the whole crustal degassing flux.

Comparison of techniques for dating of subsurface ice from Monlesi ice cave, Switzerland

AbstractThe presence of cave ice is documented in many karst regions but very little is known about the age range of this potential paleoclimate archive. This case study from the Monlesi ice cave, Swiss Jura Mountains, demonstrates that dating of cave ice is possible using a multi-parameter approach. Ice petrography, debris content and oxygen isotope composition have the potential for identification of annual growth layers, but require a continuous core from the ice deposits, limiting application of this approach. Furthermore, complete melting of ice accumulations from individual years may occur, causing amalgamation of several annual bands. Use of 3H content of the ice and 14C dating of organic debris present in the ice proved to be of limited utility, providing rather broad bounds for the actual age. Initial estimates based on 210Pb analyses from clear ice samples gave results comparable to those from other methods. The most reliable techniques applied were the determination of ice turnover rates, and the dating of anthropogenic inclusions (a roof tile) in the ice. These suggest, respectively, that the base of the cave ice was a minimum of 120 and a maximum of 158 years old. Therefore, our data support the idea that mid-latitude and low-altitude subsurface ice accumulations result from modern deposition processes rather than from presence of Pleistocene relict ice.

Environmental Tritium in the Vicinity of Tokai Reprocessing Plant

The distribution of 3H in the atmosphere, vegetations and soil water was observed in the vicinity of Tokai reprocessing plant (TRP) over the period 1990–2004. The annual means of the atmospheric HTO and HT concentrations were in the range of 12–40 mBqm−3 with a significant seasonal variation and 14–51 mBqm−3 with no seasonal variation, respectively. Long-term atmospheric dilution factors, defined as the annual mean of the atmospheric HTO concentration divided by the discharge rate of HTO from the TRP, were estimated to be 10−8–10−6 sm−3. The atmospheric HTO concentrations decreased with distance from the TRP, falling to the current background level in Japan at 5 km off-site. The HTO concentrations observed were compared with those calculated by a simple mathematical model with input data of the monthly 3H discharge rates and actual meteorological conditions. The calculations were correlated well with the observations even for only a little HTO-elevated situation, considering the naturally occurring 3H level in atmospheric vapor around the TRP. Tritium concentrations in vegetation and soil water samples were roughly the same as the atmospheric HTO concentrations, suggesting the rapid equilibrium of 3H concentrations in the atmosphere-soil-vegetation system around the TRP.

Isotope evidence of palaeorecharge and palaeoclimate in the deep confined aquifers of the Chad Basin, NE Nigeria

Groundwaters from the Quaternary and Continental Terminal Formations in the Nigeria sector of the Chad Sedimentary Basin (CSB) together with rain and surface waters have been chemically and isotopically analyzed in order to investigate sources and ages of waters, possible modern renewal and mixing of the deep groundwaters, and to infer palaeoclimate incidences. Most of the waters are slightly to moderately mineralized and are of Na-HCO3 type induced mainly by Na-feldspar weathering and ion exchange reactions. The wide range of the δ18O and δ2H values and 3H contents in the upper aquifer indicate replenishment with modern meteoric water. However, the deep system (middle and lower aquifers) with a narrow range of depleted stable isotope values and low 14C activities indicates that these waters have a palaeometeoric origin. The period of infiltration was within the humid and cooler period (35 to 40 ka BP) prior to the Last Glacial Maximum. In addition, the isotope compositions of the deep system show no mixing with modern waters. These results are in agreement with other palaeorecord studies in the Sahel zone during this period.

Constraining modern and historical recharge from bore hydrographs, 3H, 14C, and chloride concentrations: Applications to dual-porosity aquifers in dryland salinity areas, Murray Basin, Australia

Water table fluctuations and renewal rates based on 3H and 14C concentrations in bores screened within 5 m of the water table were used to estimate recharge rates in five dryland salinity areas in northern Victoria, Australia. Given the resolution of each technique both methods yield broadly similar results of 4–90 mm/yr (up to 14% of modern rainfall) that reflect the recharge rates following land clearing over the last 200 years. Deeper bores show mixing of modern recharge with older water flowing laterally through the aquifers. Recharge estimates based on Cl concentrations are up to two orders of magnitude lower (<1 mm/yr), implying that they largely reflect pre-land clearing recharge rates, as is the case elsewhere in the Murray Basin. Recharge rates are similar across the areas from upper slopes to plains, indicating that recharge occurs across substantial areas of each catchment. This is also implied by bore hydrographs in all parts of the flow systems being in phase, the presence of 3H in groundwater from across the area, and seasonal variations in salinity and δ18O values in groundwater from water table bores. Since recharge occurs across broad areas, any attempts to slow the rate of water table rise requires management of the landscape as a whole, not just the uplands. That the increased recharge since land clearing has not lowered groundwater salinity is due to the system having dual porosity, where older saline water trapped in clays within the unsaturated zone is slowly incorporated into the groundwater as the water table rises.

3H and 90Sr background in water around Tianwan NPP, China

Tianwan nuclear power plant (NPP) at Lianyungang, PR China is being in construction since 1999. To obtain the information of the 3H and 90Sr background concentrations in different water bodies around the plant and offer the estimation of the influence after its launching, 170 samples of six water bodies of vapor, ground water, drinking water, surface water, rainwater and seawater were collected, and the background concentrations of 3H and 90Sr in the water bodies are reported. The concentrations of 3H were found to vary in the range 0.5– 4.8 Bq l - 1 with an average of 1.1 ± 0.3 Bq l - 1 , and the order is: vapor > rainwater > ground water > drinking water > surface water > seawater. The concentrations of 90Sr were observed to vary in the range 1.1– 19.3 mBq l - 1 with an average of 4.4 ± 2.6 mBq l - 1 . The average concentration order is: ground water > drinking water > surface water > rain water > seawater. Negative correlation is found between the concentrations of 3H and 90Sr in different water bodies. The concentrations of the 90Sr decrease in slow slopes, while the concentrations of 3H increase. The correlation in groundwater shows a large coefficient with a value of 0.62 due to the relative stable environment. The concentrations of 3H and 90Sr are in accordance with the average level in the world. It indicates a low background radioactivity of 3H and 90Sr in the vicinity of Tianwan NPP.

Carbon and hydrogen isotopic analysis of hydrocarbons from the South Oman Salt Basin

The ^(13)C and ^2H contents of sedimentary hydrocarbons are controlled by multiple factors including the isotopic contents of the inorganic carbon and ambient water, the isotopic fractionations imposed by the enzymes of C and H assimilation and biosynthesis, and processes that take place during diagenesis and catagenesis.

PDE7A1, a cAMP-specific Phosphodiesterase, Inhibits cAMP-dependent Protein Kinase by a Direct Interaction with C

The N-terminal regulatory region of the high affinity cAMP-specific phosphodiesterase, PDE7A1, contains two copies of the cAMP-dependent kinase (PKA) pseudosubstrate site RRGAI. In betaTC3 insulinoma cells, PDE7A1 co-localizes with PKA II in the Golgi-centrosome region. The roles PDE7A1 and its regulatory region play in cAMP signaling were examined by studying interactions with PKA subunits. PDE7A1 associates with the dissociated C subunit of PKA (C), but does not bind tetrameric PKA holoenzyme. High affinity binding of C by PDE7A1 inhibits kinase activity in vitro (IC50 = 0.5 nm). The domain containing PKA pseudosubstrate sites at the N terminus of PDE7A1 mediates complex formation with C. The PDE7A1 N-terminal repeat region inhibits C activity in CHO-K1 cells and also suppresses C dependent, cAMP-independent, physiological responses in yeast. Thus, PDE7A1 possesses a non-catalytic activity that can contribute to the termination of cAMP signals via direct inhibition of C. This study identifies a novel inhibitor of PKA and a non-catalytic affect of a cyclic nucleotide phosphodiesterase.

Development and application of an eco-hydrodynamic model for radionuclides in a brackish lake: Case study of Lake Obuchi, Japan, bordered by nuclear fuel cycling facilities&lt;/p&gt; &lt;/p&gt;

In order to evaluate the transport of 3H and 137Cs radionuclides in semi-closed brackish Lake Obuchi, Japan, bordered by nuclear fuel cycling facilities, a 3D-lower-trophic eco-hydrodynamic model has been developed and validated. In a short-term prediction, 3H and 137Cs activity levels in water should be in an agreement with field measurements. It became clear that the results depended on the mixing of fresh water and seawater in the model. Moreover, a short-term simulation estimated that most 3H and 137Cs flowed to the ocean rather than remaining in the lake. Based on calculations over the past 50 years, a peak of 137Cs in sediment was in 1963, when the maximum 137Cs fallout was observed. The calculation showed a rapid decrease after that peak, however, the field measurement data gradually declined. This suggested that the process by which 137Cs accumulated from the watershed to the lake was actually slower in the field than in the model calculations. The model may be successfully applied to a variety of different environmental situations as a generic tool for evaluating the concentration and migration of 3H and 137Cs in a brackish lake.

Measurement of the Induced Radionuclides in Production of Radiopharmaceuticals for Positron Emission Tomography (PET)

The radioactive by-products contained in an entire series of target foil, [18O]H2O and synthesis apparatus were identified and quantified. From the perspective of waste management, 60Co induced in Havar foil should be taken into consideration. Because the exempt activity of 60Co in BSS is 0.1 MBq, the used Havar foil should be managed more than for 20 years. The radionuclides in the [18F]-FDG synthesis apparatus are negligible. Equivalent doses at skin and to tissues were estimated assuming a point source at a distance of 30 cm in air. The annual equivalent doses at skin and equivalent dose at deep tissues of such an operating staff will be 56 and 8.3 μSv, respectively, as two times the remove of the target foil and five hundreds times the synthesis of the [18F]-FDG. When proper radiation protection is provided, the exposure from the cyclotron management and the [18F]-FDG synthesis process will not cause meaningful radiological risk to the operating staff. The activity concentration of 3H, 180kBq-cm−3, detected in the target water, is 3,000 times the legal limit of effluent for 3H. The operators should take care of the treatment of the target water when they make a distillation for reuse and a disposal.

Application of environmental tracers to mixing, evolution, and nitrate contamination of ground water in Jeju Island, Korea

Tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated as environmental tracers in ground water from Jeju Island (Republic of Korea), a basaltic volcanic island. Ground-water mixing was evaluated by comparing 3H and CFC-12 concentrations with lumped-parameter dispersion models, which distinguished old water recharged before the 1950s with negligible 3H and CFC-12 from younger water. Low 3H levels in a considerable number of samples cannot be explained by the mixing models, and were interpreted as binary mixing of old and younger water; a process also identified in alkalinity and pH of ground water. The ground-water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seogwipo Formation in coastal areas than in water from the basaltic aquifer. Major cation concentrations are much higher in young water with high nitrate than those in uncontaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite–smectite phase boundary. The calcite saturation state of ground water increases with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water is consistent with the known history of chemical fertilizer use on the island, but increase of nitrate concentration in ground water is more abrupt after the late 1970s compared with the exponential growth of nitrogen inputs.

LONG-TERM MONITORING OF RADIOACTIVITY IN SURFACE AIR AND DEPOSITION IN NEW YORK STATE

Gross-beta activities have been determined weekly for 22 y from filtered atmospheric aerosols at seven sites in New York State. The activities, ranging from 0.1 to 0.9 mBq m(-3), varied seasonally and were evaluated in terms of meteorological factors. Cosmogenic beryllium (7Be) concentrations were determined quarterly on the air filters and weekly in deposition collected at one site. Over 98% of the air filters contained observable activity concentrations of 7Be (mean of 3 mBq m(-3)) and 210Pb (mean of 1 mBq m(-3)). However, only 20% of deposition samples contained Be concentrations above analytical detection limits. Tritium (3H) concentrations were below detection limits in deposition samples at the background site, but were present on most samples collected near a H-processing facility. Measurements of 131I were conducted weekly on charcoal canisters, with only one site showing observable concentrations (mean of 1 mBq m(-3)), due to nearby incineration of dried municipal sludge containing patient waste from hospital treatments.

Measurement of the Induced Radionuclides in Production of Radiopharmaceuticals for Positron Emission Tomography (PET)

The radioactive by-products contained in an entire series of target foil, [18O]H2O and synthesis apparatus were identified and quantified. From the perspective of waste management, 60Co induced in Havar foil should be taken into consideration. Because the exempt activity of 60Co in BSS is 0.1 MBq, the used Havar foil should be managed more than for 20 years. The radionuclides in the [18F]-FDG synthesis apparatus are negligible. Equivalent doses at skin and to tissues were estimated assuming a point source at a distance of 30 cm in air. The annual equivalent doses at skin and equivalent dose at deep tissues of such an operating staff will be 56 and 8.3 μSv, respectively, as two times the remove of the target foil and five hundreds times the synthesis of the [18F]-FDG. When proper radiation protection is provided, the exposure from the cyclotron management and the [18F]-FDG synthesis process will not cause meaningful radiological risk to the operating staff. The activity concentration of 3H, 180kBq-cm−3, detected in the target water, is 3,000 times the legal limit of effluent for 3H. The operators should take care of the treatment of the target water when they make a distillation for reuse and a disposal.