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1.
Surface and subsurface water samples for 137Cs and 239,240Pu analysis were collected in the East Sea (Sea of Japan) during August 1993. The 137Cs levels of the surface waters are quite homogeneous in the East Sea (average = 3.1±0.2 mBq kg−1). The 239,240Pu levels vary from 6 to 10 μBq kg−1 in the surface. 239,240Pu to 137Cs ratios in the surface water are within 0.002 to 0.003. The East Sea may be regarded as a part of the North Pacific Ocean in terms of 137Cs dispersal in the surface, where the 137Cs contents of the surface seawater seem to be controlled primarily by the atmospheric input. However, since our sampling was made just two months prior to the widely publicized Russian dumping incident on the 17th October 1993, our measurements may provide background data to assess the immediate impact of the Russian dumping on the levels of 137Cs and 239,240Pu in the East Sea.  相似文献   

2.
Water sampling during the 1993 IV Russian–US Joint Expedition to the Bering and Chukchi Seas (BERPAC) indicates that Pacific Ocean burdens of the long-lived radionuclide 129I are relatively low in the Pacific-influenced Arctic, particularly compared to high latitude waters influenced by the North Atlantic. These low concentrations occur despite the presence of potential submerged anthropogenic sources in the East Sea (Sea of Japan), and in the northwest Pacific Ocean, east of the Kamchatka Peninsula. The concentration of 129I entering the Arctic Ocean through Bering Strait, 0.7×108 atoms kg−1, is only slightly higher than observed in deep Pacific waters. Similar concentrations (0.44–0.76×108 atoms kg−1) measured in Long Strait indicate no significant transfer of 129I eastward into the Chukchi Sea in the Siberian Coastal Current from the Siberian marginal seas to the west. However, the concentrations reported here are more than an order of magnitude higher than the Bering Strait input concentration estimated (1.0×106 atoms kg−1) from bomb fallout mass balances, which supports other existing evidence for a significant atmospheric deposition term for this radionuclide in surface ocean waters. Near-bottom water samples collected in productive waters of the Bering and Chukchi Seas also suggest that sediment regeneration may locally elevate 129I concentrations, and impact its utility as a water mass tracer. As part of this study, two deep 129I profiles were also measured in the East Sea in 1993–1994. The near-surface concentration of 129I ranged from 0.12 to 0.31×108 atoms kg−1. The 129I concentration showed a steady decrease with depth, although because of active deep water ventilation, the entire 3000 m water column exceeded natural concentrations of the radionuclide. Atom ratios of 129I/137Cs in the East Sea also suggest an excess of 129I above bomb fallout estimates, also possibly resulting from atmospheric deposition ultimately originating from nuclear facilities.  相似文献   

3.
Concentration factor (CF=Bq kg−1 fillet/Bq kg−1 filtered sea water) values for 137Cs in fillets of cod (Gadus morhua), haddock (Merlanogrammus aeglefinus), plaice (Pleuronectes platessa) and whiting (Merlangius merlangius), were derived from fish and filtered seawater concentrations. Samples were collected in twelve sampling boxes in the North Sea over an eight-year period—1978–1985. The range of results with species, between species, and between surveys are discussed. Mean CF values of 92, 58, 39, and 150 were found in cod, haddock, plaice, and whiting respectively. These support the IAEA recommended CF value of 100 for fish in generalised dose assessments.  相似文献   

4.
238U, 232Th, 230Th and 226Ra abundances have been measured in six samples of recent Hawaiian basalt by high precision mass spectrometry, in an attempt to compare the melting process in plumes and at spreading ridges. The data reveal a very small range in (230Th/238U) activity ratio up to a maximum value of 1.02 ± 0.01, and (226Ra/230Th) activity ratios which lie between 1.10 ± 0.015 and 1.19 ± 0.02. UTh and RaTh abundances are linearly correlated demonstrating that the disequilibria predate crystallisation and differentiation. Using recently published estimates for the bulk partition coefficients of U and Th, the results are consistent with melting rates > 10−3 kg m−3 a−1 at porosities < 10−3 for dynamic fractional melting in the garnet stability field.  相似文献   

5.
Analyses are presented of137Cs,238Pu, and239,240Pu, in relation to depth in sediment, in 21 gravity cores. These cores span the ranges of times 1964–1975, and of water depths 12–2000 m; they come from three distinct sedimentation areas off the northeast coast of the United States. Although the ranges of total sediment inventories of239,240Pu and of137Cs from the various areas hardly overlap, the range of ratios of the inventories of these two nuclides is probably the same in all the areas. In the shallow-water cores the239,240Pu/137Cs ratio regularly diminishes with depth in the core, and a tendency is seen for curves of this function to have similar slopes in each area; ratios of238Pu/239,240Pu show no change with depth in these shallow-water cores. In the deeper-water cores, the239,240Pu/137Cs ratio shows no systematic change with depth, but sometimes the238Pu/239,240Pu ratio shows a minimum at the sediment surface, and is much higher deeper in the cores. We believe that these phenomena can be explained in terms of a complicated bioturbational process moving the nuclides, together, down into the sediments, of chemical resolubilization, at depth, of plutonium only, and of its subsequent upward translocation in the interstitial solution. Some re-immobilization of plutonium near the sediment surface is implied, and a mechanism is suggested for this, based on displacement of plutonium from organic complexes by the increasing concentrations, in upper layers of the sediment, of re-oxidized dissolved iron.  相似文献   

6.
We have developed techniques to determine238U,234U and232Th concentrations in seawater by isotope dilution mass spectrometry. U measurements are made using a233U236U double spike to correct for instrumental fractionation. Measurements on uranium standards demonstrate that234U/238U ratios can be measured accurately and reproducibly.234U/238U can be measured routinely to ± 5‰ (2σ) for a sample of 5 × 109 atoms of234U (3 × 10−8 g of total U, 10 ml of seawater). Data acquisition time is 1 hour. The small sample size, high precision and short data acquisition time are superior to-counting techniques.238U is measured to ± 2‰ (2σ) for a sample of 8 × 1012 atoms of238U ( 3 × 10−9 g of U, 1 ml of seawater).232Th is measured to ± 20‰ with 3 × 1011232Th atoms (10−10 g232Th, 1 1 of seawater). This small sample size will greatly facilitate investigation of the232Th concentration in the oceans. Using these techniques, we have measured238U,234U and232Th in vertical profiles of unfiltered, acidified seawater from the Atlantic and238U and234U in vertical profiles from the Pacific. Determinations of234U/238U at depths ranging from 0 to 4900 m in the Atlantic (7°44′N, 40°43′W) and the Pacific (14°41′N, 160°01′W) Oceans are the same within experimental error (± 5‰,2σ). The average of these234U/238U measurements is 144 ± 2‰ (2σ) higher than the equilibrium ratio of 5.472 × 10−5. U concentrations, normalized to 35‰ salinity, range from 3.162 to 3.281 ng/g, a range of 3.8%. The average concentration of the Pacific samples (31°4′N, 159°1′W) is 1% higher than that of the Atlantic (7°44′N, 40°43′W and 31°49′N, 64°6′W).232Th concentrations from an Atlantic profile range from 0.092 to 0.145 pg/g. The observed constancy of the234U/238U ratio is consistent with the predicted range of234U/238U using a simple two-☐ model and the residence time of deep water in the ocean determined from14C. The variation in salinity-normalized U concentrations suggests that U may be much more reactive in the marine environment than previously thought.  相似文献   

7.
Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.  相似文献   

8.
In order to establish a reliable chronology for lacustrine sediments of the Frickenhauser See (central Germany) different dating methods have been applied. A total of 17 AMS 14C dates, all within the last 2000 years, were supplemented with 137Cs/210Pb dating and varve counting of the uppermost sediments (131 years). The age–depth model for the Frickenhauser See has to cope with highly variable sedimentation rates and overlapping probability distributions of calibrated 14C dates. The uncertainty of calibrated 14C dates could be considerably reduced by including the stratigraphic relationship of the dated samples, the age information derived from short-lived isotopes and varve counting as well as an upper and lower limit of realistic sedimentation rates as ‘a priori’ information in the calibration procedure. Sets of possible age combinations obtained by repeated sampling from the modified probability distributions were used to calculate continuous age–depth relationships based on monotonic smoothing splines. The obtained age–depth model for the sediment record of the Frickenhauser See represents the average of over 16,000 such model runs and suggests a drastic increase in sedimentation rates from around 1–2 mm a−1 (200–1000 AD) to over 25 mm a−1 for the period between 1100 and 1300 AD. From then on, sedimentation rates exhibit relatively stable values around 3–9 mm a−1. ‘Conventional’ age–depth models such as general polynomial regression or cubic splines either do not include the obtained age-information in a satisfying manner (the model being too “stiff”) or exhibit “swings” causing age-reversals in the model. Although the age–depth relationships obtained for monotonic smoothing splines and mixed-effect regression are generally very similar, they differ in their respective sedimentation rates as well as in their uncertainties. Mixed-effect regression resulted in much higher sedimentation rates of more than 37 mm a−1. These results suggest that monotonic smoothing splines give better control of the age–depth model characteristics and are well suited in situations, where the integrity of 14C dates is high, i.e. the dated material represents the age of the respective layer.  相似文献   

9.
To investigate the effect of sediment contamination on the tellinid bivalve Macomona liliana, juvenile shellfish (about 1.3 mm long) were exposed to copper- and zinc-dosed sand, and sediments collected from several contaminated sites. The behavioural responses measured included burial rate, crawling and drifting. In copper-dosed sediment, a significant reduction in the number of shellfish burying after 10 min occurred at 25 mg Cu kg−1 (dry wt). After a 96-h exposure, shellfish crawled away from sediment with 10 mg Cu kg−1 (dry wt), and when a weak current was provided they left this 10 mg Cu kg−1 (dry wt) sediment by drifting. Zinc-dosed sediment slowed burial at 80 mg Zn kg−1 (dry wt), and stimulated crawling and drifting at 40 mg Zn kg−1 (dry wt). Some of the field-collected contaminated sediments slowed burial and stimulated drifting, but none affected crawling. It appears that juvenile drifting induced by sediment contamination could play a role in determining M. liliana distributions.  相似文献   

10.
Anthropogenic radionuclides have reached the Hudson estuary as global fallout from nuclear weapons testing and through local releases from commercial nuclear reactors. Significant activities of238Pu and239,240Pu (fallout-derived),134Cs and60Co (reactor-released), and137Cs (derived from both sources), have accumulated in the sediments throughout the estuary, with the primary zone of accumulation near the downstream end of the system in New York harbor. The estuary appears to have trapped nearly all of the239,240Pu delivered as fallout, and consequently, ocean dumping of dredged harbor sediment is currently the primary means for the net transport of these nuclides to coastal waters. In contrast, only 10–30% of the137Cs,134Cs and60Co delivered to the estuary have been retained on the fine particles which accumulate at a rapid rate in the harbor.The primary factors which have governed the distribution of anthropogenic radionuclides in Hudson sediments are: (1) spread of fine particles labeled with both fallout and reactor nuclides throughout the axis of the estuary, (2) differences in timing of the peak fallout years (1962–1964) and years of maximum reactor releases (1971–1972), (3) large variations in sediment accumulation rates, ranging from a few millimeters per year or less to many tens of centimeters per year, (4) appreciable desorption of137Cs and134Cs from particles at higher salinities, and (5) possible enhanced desorption of60Co at higher salinities (relative to134Cs and137Cs) which may be associated with the release of reduced manganese from the harbor sediments.  相似文献   

11.
Noble gases were extracted in steps from grain size fractions of microdiamonds ( < 100 μm) from the Kokchetav Massif, Northern Kazakhstan, by pyrolysis and combustion. The concentration of 4He in the diamonds proper (liberated by combustion) shows a 1/r dependence on grain size. For grain diameters > 15 μm the concentration also decreases with the combustion step. Both results are clear evidence that 4He has been implanted into the diamonds from -decaying elements in the surrounding matrix. The saturation concentration of 4He(5.6 × 10−4 cm3 STP/g) is among the very highest observed in any terrestrial diamonds. Fission xenon from the spontaneous fission of 238U accompanies the radiogenic 4He; the 136Xef/4He ratio of (2.5 ± 0.3) × 10−9 agrees well with the production ratio of 2.3 × 10−9 expected in a reservoir where Th/U 3.3. Radiogenic 40Ar is predominantly ( > 90%) set free upon combustion; it also resides in the diamonds and appears to have been incorporated into the diamonds upon their formation.

3He, on the other hand is mainly released during pyrolysis and hence is apparently carried by ‘contaminants’. The concentration in the diamonds proper is of the order of 4 × 10−12 cm3 STP/g, with a 3He/4He ratio of 1 × 10−8. Excess 21Ne, similarly, appears to be present in contaminants as well as in diamonds proper. These two nuclides in the contaminants must have a nucleogenic origin, but it is difficult to explain their high concentrations.  相似文献   


12.
Environmental parameters (salinity, sediment concentration, equilibration time) affecting radionuclide partitioning between sediment and seawater were experimentally investigated for Kara Sea sediments collected from nuclear waste dumping sites in Abrosimov and Stepovogo Bays off Novaya Zemlya. Adsorption kinetics were examined and the influence of salinity and sediment concentration were evaluated over the range of concentrations expected in the bays for the following radionuclides: 110 mAg; 241Am; 109Cd; 60Co; 57Co-cobalamine; 134Cs; 152Eu; 54Mn; 133Ba; 106Ru; and 85Sr. The major findings of this investigation are that 1. radionuclide distribution coefficients (Kds) were most sensitive to variations in sediment character (241Am, 60Co, 109Cd) and concentration (57Co-cobalamine, 85Sr, and 133Ba), 2. distribution coefficients generally decreased with increasing sediment concentration and 3. fast adsorption kinetics (near equilibrium ≈1 day) were observed only for 137Cs and 110 mAg. The observed differences in Kds for sediments from the two dumpsites exemplifies the importance of undertaking site-specific determinations of Kds. For purposes of confining radioactive wastes to the dumpsites in Stepovogo and Abrosimov Bays, the findings of this study indicate that based on sediment character alone, Stepovogo Bay will be more effective at retaining radionuclides than Abrosimov Bay. This is unfortunate since less radioactive waste resides in Stepovogo Bay (0.6 PBq) than in Abrosimov Bay (1.4 PBq).  相似文献   

13.
The muscle tissue of snapper (Chrysophrys auratus: Sparidae) from two areas of the New South Wales coast was analysed for methyl mercury, total mercury and selenium concentrations (134 samples from the Sydney area and 186 samples from the Nowra area, about 120 km to the south of Sydney).

The Sydney snapper ranged from 0.08 to 1.66 mg kg−1 total mercury (mean 0.32 mg kg−1), while the Nowra snapper ranged from 0.01 to 0.78 mg kg−1 total Hg (mean 0.11 mg kg−1). These latter results appear anomalously low relative to other studies in Australia and New Zealand.

Methyl mercury averaged 94.7% of the total mercury content of the Sydney snapper, and 91.3% for the Nowra snapper.

The concentrations of selenium in the muscle tissues of snapper from both areas were similar and did not increase with increasing mercury concentrations. The highest selenium concentration was 0.85 mg kg−1.  相似文献   


14.
An eddy covariance (EC) station was deployed at Solfatara crater, Italy, June 8–25, 2001 to assess if EC could reliably monitor CO2 fluxes continuously at this site. Deployment at six different locations within the crater allowed areas of focused gas venting to be variably included in the measured flux. Turbulent (EC) fluxes calculated in 30-min averages varied between 950 and 4460 g CO2 m−2 d−1; the highest measurements were made downwind of degassing pools. Comparing turbulent fluxes with chamber measurements of surface fluxes using footprint models in diffuse degassing regions yielded an average difference of 0% (±4%), indicating that EC measurements are representative of surface fluxes at this volcanic site. Similar comparisons made downwind of degassing pools yielded emission rates from 12 to 27 t CO2 d−1 for these features. Reliable EC measurements (i.e. measurements with sufficient and stationary turbulence) were obtained primarily during daytime hours (08:00 and 20:00 local time) when the wind speed exceeded 2 m s−1. Daily average EC fluxes varied by ±50% and variations were likely correlated to changes in atmospheric pressure. Variations in CO2 emissions due to volcanic processes at depth would have to be on the same order of magnitude as the measured diurnal variability in order to be useful in predicting volcanic hazard. First-order models of magma emplacement suggest that emissions could exceed this rate for reasonable assumptions of magma movement. EC therefore provides a useful method of monitoring volcanic hazard at Solfatara. Further, EC can monitor significantly larger areas than can be monitored by previous methods.  相似文献   

15.
Surface sediment samples in the Laptev Sea have average 137Cs content of 7.1 Bq kg(-1), a value intermediate between that of the western Kara Sea (23 Bq kg(-1) and the East Siberian Sea (4.2 Bq kg-'). Both surface sediment content and sediment inventory of 137Cs in the Laptev Sea sediments show significant variability, and the influence of a variety of environmental factors.137Cs concentrations in the Laptev Sea surface sediments range from 0.8 to 16 Bq kg(-1). There is a marked increase in 137Cs content of surface sediment samples collected near the Lena River delta, and a local enrichment in the 137Cs inventories at these sites is also evident. Fine-grained mixed-layer illite/ smectite rich sediments in the estuary provide effective adsorption sites to fix 137Cs, in spite of desorption processes associated with low salinities in estuarine mixing. The Lena River-Laptev Sea mixing zone is a major site of sea-ice production. River and shelf sediments are incorporated into sea-ice formed in this region (Holmes and Creager, 1974). The irregular 137Cs activity profiles of the Lena River estuary cores indicate disturbance or removal of 137Cs-laden sediments via sea-ice related processes. Lena River and Estuary sediments may have served as a secondary source (i.e. other than direct fallout) of 137Cs in sea-ice. North-east of the Lena River estuary, sediment contains a thin layer of 137Cs-bearing material over an erosion surface. The 137Cs-laden surface layer may be the result of transient deposition of estuarine sediments being delivered by sea-ice or spring floods.  相似文献   

16.
Accumulation of the radionuclides 241Am, 110mAg, 133Ba, 109Cd, 57Co-cobalamine, 60Co, 134Cs, 152Eu, 54Mn, 106Ru and 65Zn in the brown macroalga Fucus vesiculosus (L.) Phaeophyceae, was compared at 2°C and 12°C in a series of laboratory radiotracer experiments. Concentration factors in the thallus were temperature-dependent and significantly decreased at 2°C for 110mAg, 109Cd, 60Co, 54Mn and 65Zn (CF = 439, 51, 101, 92 and 162, respectively) but not for 241Am, 133Ba, 134Cs, 152Eu and organic 57Co (CF = 329, 210, 3.3, 470 and 214, respectively); hence, for these last isotopes concentration factors in this species derived from temperate latitude (12°C) studies can probably be applied to radiological assessments made under Arctic conditions. Between 2 and 14 days of depuration, the radionuclides, except 133Ba and 134Cs, remained tightly bound to the alga. Our results suggest that: 1. temperature must be considered when modelling the radiological impact of radioactive waste dumping in the Arctic Seas; and 2. Fucus spp. would be excellent bioindicators of radionuclide contamination and dispersion in the Barents and Kara Seas.  相似文献   

17.
The toxicity of marine sediments in Victoria Harbour, Hong Kong   总被引：4，自引：0，他引：4  
When the toxicity of marine sediment in Hong Kong was evaluated, it was found that the seven sediments collected within Victoria Harbour were severely contaminated with heavy metals, at concentrations many times higher than those in sediments collected from outside the harbour. The highest metal content was recorded in site VS14 (located near the airport runway and the industrialized area), with copper, zinc, lead and chromium values of 3789, 610, 138 and 601 mg kg−1 dry wt, respectively. This site also had the greatest alkaline phosphatase activities (15 fluorescent intensity unit g−1 wet wt), the largest number of total coliforms (910 CFU g−1 wet wt) and sulphate-reducing bacteria (8.5 × 104 cells g−1 wet wt), implying that site VS14 was also contaminated with organic matter and nutrients. Sediment bioassays, Microtox and algal tests, demonstrated that sediment elutriates obtained from site VS14 were of greatest toxicity. The EC10 value in Microtox tests was 17% elutriate, and the 96-h IC50 values using Skeletonema costatum and Dunaliella tertiolecta were 40 and 79% elutriate, respectively. No toxic effects were found in sediment samples collected from the control site outside Victoria Harbour. Significant correlations were found between the results of the algal toxicity test (using S. costatum) and the coliform count and metal content of the sediments. The Microtox test was less sensitive than the algal bioassay, and no sediment elutriate, even from the site mostly contaminated by heavy metals, caused more than 50% inhibition of the light-emitting activity of the bacteria. In this study, S. costatum (the diatom) provided a more sensitive and reliable test species than D. tertiolecta (the flagellate) in differentiating the toxicity of marine sediments.  相似文献   

18.
238Pu,239Pu and137Cs in rain and dry fallout and90Sr in rain samples were measured at Woods Hole, Massachusetts, from June 1976 through December 1977. The dry fallout was estimated to be about 7.8% of the total deposition of239Pu and137Cs.239Pu/137Cs ratios, almost constant at about 0.011 in rain or dry fallout, February through December 1977, suggested that fractionation between the refractory and volatile radionuclides is insignificant in stratospheric fallout. This supports the idea of regional homogeneity of radionuclide ratios in fallout.  相似文献   

19.
Pesticides and herbicides including organochlorine compounds have had extensive current and past application by Queensland's intensive coastal agriculture industry as well as for a wide range of domestic, public health and agricultural purposes in urban areas. The persistent nature of these types of compounds together with possible continued illegal use of banned organochlorine compounds raises the potential for continued long-term chronic exposure to plants and animals of the Great Barrier Reef. Sediment and seagrass samples were collected from 16 intertidal and 25 subtidal sampling sites between Torres Strait and Townsville, near Mackay and Gladstone, and in Hervey and Moreton Bays in 1997 and 1998 and analysed for pesticide and herbicide residues. Low levels of atrazine (0.1–0.3 μg kg−1), diuron (0.2–10.1 μg kg−1), lindane (0.08–0.19 μg kg−1), dieldrin (0.05–0.37 μg kg−1), DDT (0.05–0.26 μg kg−1), and DDE (0.05–0.26 μg kg−1) were detected in sediments and/or seagrasses. Contaminants were mainly detected in samples collected along the high rainfall, tropical coast between Townsville and Port Douglas and in Moreton Bay. Of the contaminants detected, the herbicide diuron is of most concern as the concentrations detected have some potential to impact local seagrass communities.  相似文献   

20.
Analytical procedures in the determination of iodine-129 (half-life: 1.6×107 y) have been studied using accelerator mass spectrometry (AMS), with special references to the separation procedures of iodine from soil samples for the AMS measurement. Iodine was successfully volatilized from soil samples by pyrohydrolysis at 1000 °C and collected in a trap solution. Iodine was purified from the matrix by solvent extraction. Finally, it was precipitated as silver iodide to make a target for AMS. In order to obtain information on the 129I/127I ratio in a chemical blank (or iodine carrier), we have determined the ratios in several iodine reagents and found that the ratios fell in a narrow range around 1.7×10−13. The detection limit for soil sample (1 g material) by the present method was about 0.01 mBq/kg or 4×10−11 as the ratio of stable iodine (129I/127I ratio), i.e. these values were much better than that by neutron activation analysis (NAA) used in our previous studies. We have applied this method in the analysis of soil samples collected from different places in Japan. We could successfully determine 129I in soil samples with low 129I concentrations, which could not be detected by NAA. Sample size necessary for the soil analysis by AMS was only about 0.5 g or less, whereas about 100 g of the sample were required for NAA [Muramatsu, Y., Ohmomo, Y., 1986. Iodine-129 and iodine-127 in environmental samples collected from Tokaimura/ Ibaraki, Japan. Sci. Total Environ. 48, 33-43]. Using this method, new data were obtained for the 129I levels in 20 soil samples collected from background areas far from nuclear facilities, and the ranges were 1.4×10−5−4.5×10−3 Bq/kg as 129I concentrations and 3.9×10−11−2.2×10−8 as 129I/127I ratios. These values are useful in understanding the 129I levels in Japanese environments. Higher 129I concentrations were observed in forest soils than those in field and rice paddy soils should be related to the interception effect of atmospheric 129I due to tree canopies. Relatively high 129I/127I ratios found in rice paddy soils could be explained by their low stable iodine concentrations which were caused by the desorption of stable iodine from the rice paddies during the cultivation.  相似文献   

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