Tritium in surface waters, tap water and in precipitation in Poland during the 1994–1999 period

Concentrations of tritium in environmental waters (precipitation, rivers, lakes, tap water) have been determined using electrolytic enrichment and liquid scintillation counting. In waters of big rivers (the Vistula and the Odra rivers), lakes and tap water the annual average concentrations were similar to each other being from 1.4 to 1.9 Bq·dm^-3. These concentrations were similar to those in the precipitation in which they ranged from 1.7 to 2.2 Bq·dm^-3. The lowest tritium concentrations were found in waters of the Seashore Region rivers (average for 1994–1999 was 1.1 Bq·dm^-3). The tritium concentrations in surface waters and in precipitation are still higher than that of natural level. The data obtained show that tritium concentration in the water of rivers might depend on the size of drainage area. The observed seasonal variations of tritium concentration in the precipitation collected in Warsaw and at the Mount Sniezka indicate the stratospheric source of tritium. It was found that about 30% of tritium deposited with precipitation is removed to the Baltic Sea with river waters.     

Tritium concentration in ocean

Surface seawater and water vapor about 10 m above the sea level were collected in the Pacific and Indian Oceans during the expedition of KH-96-5 to examine tritium concentrations in open sea. The tritium concentration in the water vapor was one order of magnitude higher than that in the surface seawater, attributed to downward movement of naturally occurring tritium from stratosphere to troposphere.     

Tritium concentrations of river water on northern and southern islands of Japan

Tritium concentrations were measured for river waters on two islands in Japan. Significant difference was observed on the distribution of tritium concentrations on both islands, the river water samples from the northern island had higher concentrations and the average was about twice compared to that from the southern island. Higher tritium concentration in precipitation and the larger area of the northern island would be responsible for higher tritium concentrations in river waters.     

Natural tritium determination in groundwater on Mt. Etna (Sicily, Italy)

Tritium is a naturally occurring radionuclide, due to interactions of cosmic-rays with the upper layers of the atmosphere; but its presence in the environment is mainly due to residual fallout from nuclear weapons atmosphere tests, carried out from 1952 till 1980. Tritium reaches the Earth’s surface mainly in the form of precipitation, becoming part of the hydrological cycle, then the interest of tritium content analysis in drinking water is both for dosimetry and health-risk and for using tritium as a natural tracer in the groundwater circulation system. This paper presents results from a survey carried out in the Mt. Etna area (east and west flanks) and in the southern side of Nebrodi in Sicily (Italy), in order to determine tritium activity concentrations in water samples by using liquid scintillation counter. The investigated areas show quite low tritium concentrations, much below the Italian limit of 100 Bq L^?1 for drinking water and even comparable with the minimum detectable activity value. The effective dose due to tritium for public drinking water consumption was also evaluated.     

Determination of tritium in natural waters

A study of the tritium content of precipitation and of river water samples, collected during a seasonal maximum of tritium concentration in 1976 is given. The measurements were made for precipitation in Belgrade from April to December 1976, and for river water from the Sava (in Belgrade), the Tisa at 137 km, and the Danube at 1425 km, 1174 km, 861 km from the confluence. The maximum monthly value of the tritium content of precipitation is 135 TU, and the Danube at 1425 km has a maximum of 196 TU (627 pCi/l). In general, there is no correlation between the amount of precipitation and river water with tritium content.     

Monitoring of environmental radiation and radionuclides around nuclear fuel cycle facilities from 1989 to 1995

Aomori Prefectural Govemment and Japan Nuclear Fuel Limited started environmental radiation monitoring around Nuclear Fuel Cycle Facilities in April 1989. External radiation is measured by NaI(TI) scintillator and Themoluminescence dosimeter. The level of external radiation is relatively low in the winter due to snow. We have collected terrestrial samples of drinking water, soil, agricultural products and marine samples of seawater, sea sediment, seafood, etc. periodically. We have measured many radionuclides and fluoride in these samples. In soil sample,^239+240Pu ratio to¹³⁷Cs was almost constant at all sampling points. A correlation was observed between salinity and concentration of tritium, uranium and fluoride in lake water of Lake Obuchinuma. The correlation between¹³⁷Cs and^239+240Pu in lake sediment was observed in each lake.     

Tritium concentration in fresh,brackish and sea-water samples in Rokkasho-Village,Japan, bordered by nuclear fuel cycle facilities

Summary In order to identify the concentration of tritium (³H) in areas of fresh, brackish and sea water, bordered by nuclear fuel facilities at Rokkasho-Village, Aomori, Japan, water samples were collected from 2001 to 2004 at six points in those areas. Concentration ranges of tritium in fresh river water, brackish lake and seawater samples were 0.60 to 1.1 Bq^. l^-1(mean value 0.79 Bq^. l^-1), 0.20 to 0.87 Bq^. l^-1(mean value 0.41 Bq^. l^-1), and 0.08 to 0.25 Bq^. l^-1(mean value 0.15 Bq^. l^-1), respectively. Relationships between tritium concentrations and salinity in the samples showed a clear negative correlation. Moreover, the seasonal variation of tritium in water from Rokkasho-Village was high in spring and low in fall.     

Tritium content as indicator of environmental character on Taiwan Island

Environmental characters have been established by tritium contents in well water, coastal seawater and reservoir water collected from various places around Taiwan island. Tritium concentrations of samples were detected by a liquid scintillation analyzer TRI-CARB-LSC 2550 TR mode, with a low level standard quench curve. After samples were concentrated by electrolysis, tritium concentration was detected in optimum conditions of LLLSA. An electrolytic enrichment technique was also developed with a eurrent density of 100 mA/cm² and 0.4–0.6% (Na₂O₂) electrolyte in concentrated samples. Data observed show a lower tritium concentration for coastal seawater than for wells in the same area. The tritium concentration ratio of well and coastal seawater on the western side of Taiwan is 4.000 and on the eastern side 5.801. Tritium content of reservoir water is related to the logarithm of effective volume capacity.     

Variation of tritium concentration in the course of the degradation of fresh pine needles on a forest floor

Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization. The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor. The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which is observed in the general environment.     

Levels of tritium concentration in the environmental samples around JAERI TOKAI

By the operation of research reactors, tritium-handling facilities, nuclear power plants, and a reprocessing facility around JAERI TOKAI, tritium is released into the environment in compliance with the regulatory standards.To investigate the levels of tritium concentration in environmental samples around JAERI, rain, air (vapor and hydrogen gas), and tissue-free water of pine needles were measured and analyzed from 1984 to 1993. Sampling locations were determined by taking into consideration wind direction, distance from nuclear facilities, and population distribution. The NAKA site (about 6 km west-northwest from the TOKAI site) was also selected as a reference point.Rain and tissue-free water of pine needles were sampled monthly. For air samples, sampling was carried out for two weeks by using the continuous tritium sampler. After the pretreatment of samples, tritium concentrations were measured by a low background liquid scintillation counter (detection limit is 0.8 Bq/l).Annual mean tritium concentrations in rain observed at six points for 10 years was 0.8 to 8.9 Bq/l, which decreased with distance from the nuclear facilities. Tritium concentrations in rain obtained at Chiba City were around 0.8 Bq/l (1987–1988) and those at the NAKA site were 0.8 to 3.8 Bq/l.Annual mean HTO concentrations in air at three points for 10 years were 9.2×10^–2 to 1.1 Bq/m³, although HT concentrations in air, ranging from 1.7×10^–2 to 5.8×10^–2 Bq/m³, were not influenced by the operation of the nuclear facilities.Annual mean tritium concentrations in tissue-free water of pine needles at four points for 10 years were 1.4 to 31 Bq/l. Those at the NAKA site ranging from 1.4 to 6.2 Bq/l were in good agreement with the reported value by Takashima of 0.78 to 3.0 Bq/l at twenty-one locations in Japan.Monthly mean HTO concentrations in air for 10 years showed a good correlation with absolute humidity, while other samples showed no seasonal variation.Higher level tritium concentrations in rain, in air (vapor), and in tissue-free water of pine needles at the TOKAI site were caused by the tritium released from the nuclear facilities.The committed effective dose equivalent to the member of general public, estimated using the maximum tritium concentration in air (1.1 Bq/m³), was 0.23 Sv, which was about 1/4000 of dose limit for general public.     

Seasonal variation in the isotopic contents of precipitation in Korea

Tritium and other stable isotopes in precipitation were analyzed on a monthly based on Jeju Island and in Daejeon Korea and variations between the island and continent were compared. The tritium concentration in Daejeon ranged from 2.27 to 15.71 TU and on Jeju from <0.5 to 5.4 TU. The maximum value of the tritium content was in March and the minimum in July and August due to the dilution effect of heavy rain. The tritium content in precipitation on Jeju Island was lower than in Daejeon and the results reflected the general tritium content value in the Northern Hemisphere. The stable isotope analysis results showed that the mean value of δ ¹⁸O (‰) was ?6.28 and ranged from ?11.70 to ?1.67. Further the mean δD (‰) value was ?36.33 and ranged from ?85.56 to 4.27. The mean deuterium excess value (d-value) was 13.89  ‰ and ranged from 3.33 to 33.61 ‰.     

Tritium Concentrations of Natural Waters in Rokkasho-Mura

There are two types of lakes in the vicinity of the nuclear fuel cycle facilities in Rokkasho-mura. One is a brackish lake, Obuchinuma Lake, and the other is a freshwater lake, Takahokonuma Lake. Tritium concentrations in Obuchinuma Lake had a good negative correlation with salinity at any sampling point and period. We consider that the water of Obuchinuma Lake has been only slightly influenced by precipitation depending on the ratio of seawater and river water of the Futamata River. Tritium concentrations in Takahokonuma Lake ranged from 0.6 to 1.5 Bq·1^-1, and were higher than that in precipitation in Rokkasho-mura. Tritium concentration in rivers flowing into the lakes ranged from 0.7 to 2 Bq·l^-1, and were higher than that in the precipitation. It is assumed that ground waters with higher levels of tritium inflow into the rivers.     

Tritium concentrations of the deep sea-water in the Japan Sea and the Pacific Ocean

Tritium concentrations were determined for sea-water samples collected from the Japan Sea and the Pacific Ocean. In the Japan Sea, it was recognized that tritium was distributed around 2000 m in depth. This means that the vertical mixing of water mass is taking place. On the other hand, in the Pacific Ocean, the tritium concentration appears to reach zero at about 1000 m although more than 1 TU concentration are detected for samples collected from deeper water. Hypothetical origins of tritium in the deep water in the Pacific Ocean are discussed.     

Tritium measurement in the Western Caucasus

Measurement of tritium in water of rains, springs, wells, mud volcanoes and rivers, lakes of the Western Caucasus (Krasnodar region) has been carried out since 1997 for hydrogeology, engineering geology, ecology and seismology. Electrolytic cells with spiral electrodes and the big multiwire proportional chamber were used for low tritium concentration measurements on expeditions. With the new design of the cell the enrichment factor of 64.0 ± 1.5 % was obtained during the electrolytic process. Correlation of tritium concentration is observed in mud volcanoes and spring water with regional seismicity. The long-term tritium data are shown in natural waters in South Russia.     

Mechanism of 7Be scavenging from the atmosphere through precipitation in relation to seasonal variations in Rokkasho Village, Aomori Prefecture, Japan

⁷Be deposition fluxes and atmospheric concentrations were measured at Rokkasho Village, Aomori Prefecture, Japan, from 2000 to 2005. It was confirmed that the ⁷Be deposition fluxes were minimum in summer, and the fallout maximizes in winter. The atmospheric concentration of ⁷Be was especially low in summer, and high in the other three seasons. A positive correlation was observed between the amount of precipitation and ⁷Be deposition. Clear seasonal differences were evident among the ratios of ⁷Be deposition flux to precipitation amounts in the four seasons. The ratios were especially high in winter, higher than those in the other three seasons. ⁷Be deposition flux was estimated by a simple simulation model using atmospheric ⁷Be concentrations and local meteorological data. As a result, the estimated deposition value was relatively lower than the measured value in winter.     

Temporal variation of tritium concentration in tree-ring cellulose

Tritium concentration of organically bound hydrogen has been measured during the 1941 to 1987 period using a cellulose fraction extracted from pine tree grown in Tatsunokuchi-machi, Ishikawa Prefecture, Japan. It was concluded that most of the tritium bound in cellulose was supplied from the mixture of underground water in the root zone of the pine tree. Underground water was strongly influenced by the precipitation and waters with different residence times. This revised version was published online in July 2006 with corrections to the Cover Date.     

Volume reduction and tritium retention factor in electrolytic enrichment of water

Volume reduction(N), tritium retention factor (R), tritium concentration factor(Z) and apparent separation factor(beta) were measured on the large and small electrolytic cell systems. The relative variation of R was smaller than that of Z. So, it is recommended to use R in calculation of tritium concentrations in water samples. Furthermore, it was empirically revealed that R can be obtained only from N if a reliable beta-value is previously known. Therefore, it is possible to obtain R without electrolysis of the tritium standard solution. Taking into account the above facts, the so-called non-spike analysis of tritium, in which electrolytic enrichment and liquid scintillation counting are combined, becomes practicable.     

Separation of HT and HTO in the atmosphere with porous Vycor glass tube

The continuous selective monitoring of tritium gas (HT) in the air containing HT and tritiated water vapor (HTO) was investigated by using the separation cell made of porous Vycor glass tube. On admitting the air containing HT or HTO into the separation cell, HT permeated immediately through the Vycor tube depending on the partial pressure, however, HTO permeated very slowly through the Vycor tube after initial induction period. The initial induction period was elongated with a rise of the temperature of separation cell and then the permeability of HTO decreased remarkably. In the air containing HT and water vapor, the permeation of HT through the Vycor tube was considerably restricted by the water vapor adsorbed on the Vycor tube at lower temperature (at 25 degrees C) but it was hardly affected by water vapor at higher temperature (greater than 50 degrees C) since water vapor was difficult to adsorb on the Vycor tube. These results indicated that HT in the air containing HT and water vapor can be continuously monitored by using the separation cell made of the porous Vycor glass tube.     

Fundamental study on decontamination of tritium from gaseous phases by copper oxide

Some fundamental studies on removal of tritium from gaseous streams by a small column of copper oxide were carried out. An about 10 cm length of column packed with 100 g of copper oxide was examined on the conversion ratios of hydrogen and tritium into water. The experiment with hydrogen of 0.1% in argon showed that the logarithmic plot of remaining ratio of hydrogen by passing through the column is proportional to the reciprocal of gas flow rate and to the length of oxide column. The oxide column was also used for treating tritium-bearing waste gas from an evacuating system of alpha D-T neutron generator. It was observed that at column temperatures lower than 450 degrees C the conversion ratio of tritium in the waste gas into water is considerably smaller than that of hydrogen of 0.1% in argon.     

Vertical distribution of rhenium in seawater samples collected at three locations off the coast of Aomori, Japan

Summary The behavior rhenium in surface seawater (0-30 m) was studied using the samples collected at three locations off the coast of Aomori Prefecture, Japan. The physico-chemical forms of Re in seawater from other locations were also studied to verify the Aomori findings. It was found that almost 100% of Re was in dissolved forms, mainly ReO₄^-, therefore, the Re concentration was constant from the surface to 30 m depth and ranged from 6.1-7.4 ng^. kg^-1. The Re concentration in the Sea of Japan side was slightly lower than those in the Pacific Ocean side. Possibly, low Re concentration was added by river waters from Japan and/or the Asian continent to the Sea of Japan side.