129I Concentrations Research Articles

Anthropogenic 236U and 129I in the Mediterranean Sea: First comprehensive distribution and constrain of their sources

The first basin-wide distribution of 236U/238U atom ratios and 129I concentrations is presented for the Mediterranean Sea. During the GEOTRACES GA04S-MedSeA expedition in 2013 seawater was collected from 10 vertical profiles covering the principal sub–basins of the Mediterranean Sea. The main objective was to understand the distributions of 236U and 129I in relation to the water masses, and to constrain their sources in this region. The 236U/238U atom ratios and the 129I concentrations ranged from (710±40)×10−12 to (2220±60)×10−12 and from (4.0±0.1)×107 to (13.8±0.3)×107at·kg−1, respectively. The results show that radionuclide–poor Atlantic Water is entering at the surface through the Strait of Gibraltar whereas comparably radionuclide-enriched Levantine Intermediate Water is sinking in the Eastern Basin and flowing westward at intermediate depths. Low radionuclide levels were found in the oldest water masses at about 1000–2000m depth in the Eastern Basin. At greater depths, waters were relatively enriched in 236U and 129I due to dense water formation occurring in both, the Eastern and Western Basins. The inventories of 236U and 129I cannot be explained only by global fallout from atmospheric nuclear bomb testings carried out in the 1950s and 1960s. We estimate that the liquid input of 236U from the nuclear reprocessing facility of Marcoule (France), via the Rhône river, was of the same order of magnitude than the contribution from global fallout, whereas liquid and gaseous releases of 129I from Marcoule were up to two orders of magnitude higher than global fallout. For both radionuclides, the contribution from the Chernobyl accident is found to be minor.

127-I levels in Ontario Bulk Tank Milk and its Association with Groundwater, Milking Management, and Other Risk Factors

The objectives of the present study were to determine the iodine concentration in milk sampled from 80 commercial dairy farms located in eastern (n=58) and southwestern (n=22) Ontario, and to identify if the iodide content of groundwater consumed by the lactating herd, along with other factors, are associated with higher bulk milk iodine (BMI). A bilingual questionnaire addressing water consumption, nutrition, milking management practices, and well characteristics was completed by each producer. The 127I concentration in milk and groundwater samples was established using inductively coupled plasma mass spectrometry. Potential predictor variables were screened for univariable significance (p<0.05), and a general linear regression model was fitted to assess associations between BMI and explanatory variables such as 127I in water, well depth and age, water treatment, the use of iodine-based pre or post-dips, application strategies and post-dip coverage goal. Results of the data analysis suggest that there is a strong positive correlation between the iodide content of groundwater and BMI levels (p<0.001). Post-milking practices including the use of an iodine-based teat disinfectant, the application strategies of a post-milking teat disinfectant and overall coverage goal of the solution on teats were also significantly (p<0.05) associated with increased BMI levels. These results suggest a significant association exists between BMI levels in relation to post-milking management practices and the iodine content in groundwater consumed by the lactating herd. Post-milking practices and drinking water containing excessive levels of iodine should be monitored frequently and where needed mitigation strategies implemented to prevent high BMI levels on farm.

127- I levels in Ontario Bulk Tank Milk and its Association with Groundwater, Milking Management, and Other Risk Factors

The objectives of the present study were to determine the iodine concentration in milk sampled from 80 commercial dairy farms located in eastern (n=58) and southwestern (n=22) Ontario, and to identify if the iodide content of groundwater consumed by the lactating herd, along with other factors, are associated with higher bulk milk iodine (BMI). A bilingual questionnaire addressing water consumption, nutrition, milking management practices, and well characteristics was completed by each producer. The 127I concentration in milk and groundwater samples was established using inductively coupled plasma mass spectrometry. Potential predictor variables were screened for univariable significance (p0.05), and a general linear regression model was fitted to assess associations between BMI and explanatory variables such as 127I in water, well depth and age, water treatment, the use of iodine-based pre or post-dips, application strategies and post-dip coverage goal. Results of the data analysis suggest that there is a strong positive correlation between the iodide content of groundwater and BMI levels (p0.001). Post-milking practices including the use of an iodine-based teat disinfectant, the application strategies of a post-milking teat disinfectant and overall coverage goal of the solution on teats were also significantly (p0.05) associated with increased BMI levels. These results suggest a significant association exists between BMI levels in relation to post-milking management practices and the iodine content in groundwater consumed by the lactating herd. Post-milking practices and drinking water containing excessive levels of iodine should be monitored frequently and where needed mitigation strategies implemented to prevent high BMI levels on farm.

Comparative Analysis of Calculation Possibilities of MACCS and RODOS Computer Codes for Emergency Response and Analysis of Radiation Consequences of Severe Accidents at NPPs

The paper presents a brief description of the Real-time On-line Decision Support System (RODOS) and MELCOR Accident Consequence Code System (MACCS) and evaluates the application of these codes for assessment of radiation impact on the public and environment in case of a severe accident at NPP in real time mode. The experts performed comparative analysis of results obtained from calculations using RODOS, WinMACCS and HotSpot codes. In the framework of the research, the chosen comparative criteria were assessed: total effective dose, thyroid equivalent dose, skin equivalent dose, I-131 and Cs-137 ground concentration at different distances up to 50 kilometers from the source of release.

Measurement, simulation, and meteorological interpretation of medium-range transport of radionuclides to Korea during the Fukushima Dai-ichi nuclear accident

Two radionuclides (131I and 137Cs) were measured and simulated over the Korean Peninsula during the Fukushima Dai-ichi nuclear accident, and the resulting meso-scale meteorological characteristics were explored in order to interpret the medium-range transport of radionuclides from the site of the Fukushima Dai-ichi nuclear accident to the Korean Peninsula. Peak concentrations of radionuclides were detected across all sites in Korea for a period of April 2–8, 2011, with maximum concentrations of 131I and 137Cs at 3.12mBq/m3 (on April 6), and 1.25mBq/m3 (on April 7), respectively; the highest levels on record in Korea since measurements began. The multi-particle Lagrangian model, the FLEXPART simulation based on the National Centers for Environmental Prediction/Global Forecast System (NCEP/GFS), successfully explored these high radionuclide peaks resulting from long- and medium-range transport processes from the accident site.The meteorological feature of the medium-range transport exploited in this study is the veering meso-scale circulation, in association with the presence of a blocking anticyclone, and its subsequent evolution with propagation eastwards over northeast Asia, which was one of the important factors in explaining the advection and redirection of radionuclides from the accident site to the Korean Peninsula. The blocking situation of the anticyclone, centered on the Korean Peninsula, lasted for two days (on April 4–5, 2011), and the northwesterlies and subsequent northerlies advected the radionuclides from the accident site to the southern Sea of Japan. They were then redirected towards Korea due to the veering circulations produced by the blocking anticyclone. The position-evolution of the anticyclone was concurrent with the timing of the transport of the highest level of 137Cs concentrations recorded in Korea. The vertical meteorological structure of the blocking anticyclone was also well featured to maintain its position due to the persistent compensation provided by being aloft a convergence zone, which is in good accordance with the location of the ridge on the 500hPa level.

Gaussian plume atmospheric modelling and radiation exposure calculations following the cremation of a deceased thyroid cancer patient treated with iodine-131

Shortly after treatment with 7200 MBq of 131I, a thyroid cancer patient died and was subsequently cremated. Calculations of the atmospheric emissions of 131I from the crematorium flue were performed using a standard atmospheric pollution Gaussian Plume Dispersal model. Estimates of whole-body and thyroid dose of those potentially exposed were made using OLINDA/EXM dosimetry software. Under the meteorological conditions prevalent at the time of the cremation, and depending on the actual release rate of the 131I, the Western Australian legal limit of 3.7 Bqm−3 for atmospheric emissions of 131I may have been exceeded for distances of up to 440 and 1610 m downwind of the crematorium chimney, with the maximum concentration being between 33 and 392 Bqm−3. Assuming 16% of the inhaled 131I was taken up in the thyroid with the balance in the remainder of the body, the radiation dose to maximally exposed individuals was calculated to be approximately 17.7 μSv to the thyroid and 0.04 μSv to the whole-body. Despite the maximum allowable atmospheric 131I concentration of 3.7 Bqm−3 being exceeded, as the number of people immediately downwind of the crematorium flue in the high concentration zones was very low, and considering the relatively high tolerable dose to the thyroid, the radiation dose to people was probably not a problem in this case. The local limit of 1000 MBq of 131I for the cremation of a deceased patient is reasonable, but with adequate precautions could be significantly increased without any harmful effects to people or the environment.

希ガス計数を利用したプルーム通過時間帯決定によるモニタリングポスト測定値を用いた空気中<sup>131</sup>I濃度推定手法の改良

The purpose of this study is to improve a quick method for estimation of 131I concentrations in the air using data measured by monitoring posts in case that a nuclear disaster occurs. In this method, 131I concentrations were estimated by multiplying 131I count rates of cloud-shine measured with Na(Tl) detector by concentration conversion factor. A previous study suggested that it was difficult to determine passing-through time of plume from temporal change of 131I count rates or dose rate. Our study applies the method for estimating passing-through time of plume from temporal change of noble gas counts. The 131I concentrations in the air at Oarai center, Japan Atomic Energy Agency resulting from the accident at the Fukushima Daiichi Nuclear Power Station were estimated by proposal technique. The result of comparison of this method with sampling method for 131I concentrations in the air were within factor 3.

Unusual breast radioiodine uptake in a nonbreastfeeding woman with papillary thyroid carcinoma

Background: A 48-yearold woman underwent total thyroidectomy for a multinodular goiter. Histopathological examination revealed papillary thyroid carcinoma. The patient was referred to the nuclear medicine department for ablative dose of iodine-131 iodine (3.7 GBq) and post therapy radioiodine scan. Thyroglobulin level was at 11 ng/ml. Procedure: Planar whole-body radioiodine scintigraphy was performed in the anterior and posterior projections 5 days after the ablative dose of 131I. Single-photon emission computed tomography (SPECT-CT) was additionally performed for anatomical localization of the thoracic radioiodine-avid foci. Findings: The whole-body radioiodine scan revealed cervical radioiodine uptake, in relation to a post-surgical residue. The scan also showed two quasisymmetrical thoracic radioiodine-avid foci located probably outside the pulmonary fields (Figure 1). On the SPECT-CT scan these thoracic foci of radioiodine uptake were seen to correspond to uptake in both breasts (Figure 2). Conclusion: Whole-body scintigraphy after 131I ablation showed unusual bilateral focal uptake in the breasts in a patient with papillary thyroid carcinoma. This appears to be a rare case of falsepositive uptake in a non lactating woman. Comments: The knowledge of the usual sites of radioiodine concentration in the body is essential for the correct interpretation of the whole-body scintigraphy. However, the real pitfall in the correct diagnosis is concentration of 131I in a lesser known site.

福島県モニタリングポストのNaI（Tl）検出器波高分布データを用いたプルーム中Xe-135, I-131, I-132, I-133およびTe-132放射能濃度の推定

The Xe-135, I-131, I-132, I-133 and Te-132 concentrations in plumes at the monitoring posts in Fukushima prefecture in March 2011 were estimated using the pulse height distribution obtained from a NaI(Tl) detector, which were available to the public. Several corrections to the pulse height distribution were necessary owing to high count rates. The contribution to the count rates from each radionuclide except Xe-135 accumulated around each monitoring post was estimated using a method based on the time history of the peak count rate proposed by the authors. The concentration of each radionuclide in the plume was converted from the peak count rate using the response of the NaI(Tl) detector calculated with the egs5 code for a model of a plume containing a uniform distribution of radionuclides. The obtained time histories of Xe-135, I-131, I-132, I-133 and Te-132 concentrations in air at a fixed point in March 2011 were the first ones for Fukushima prefecture. The results at five monitoring posts near Fukushima Daiichi Nuclear Power Station were used to characterize radionuclides in the plume before March 15, soon after the accident. The results at three monitoring posts, Naraha-town Shoukan, Hirono-town Futatsunuma and Fukushima-city Momijiyama, which were analyzed during almost all of March, were used to characterize radionuclides in the plume in the period after March 14. It was fourd that Xe-135 was dominant on March 12 and Te-132 increased from March 13. For the radionuclides of iodine, I-131, I-132 and I-133 were detected with almost the same concentration for the first few days after the reactor shutdown.

Radioecological investigation of 3H, 14C, and 129I in natural waters from Fuhrberger Feld catchment, Northern Germany

Ongoing radionuclide releases from nuclear facilities, e.g. from reprocessing plants, but also from nuclear reactors require monitoring of the environment. Particularly drinking water reservoirs are prone to possible radionuclide accumulation fostering the need for routine surveillance. In this work, we investigated tritium (3H), radiocarbon (14C), and iodine-129 (129I) activity levels in natural aquatic samples at the water protection area of Fuhrberger Feld near Hannover city, Northern Germany. For that aim, a low-level liquid scintillation counting (LSC) technique was used to measure 3H in the water samples based on a distillation process after alkaline permanganate treatment. Isotopic ratios for both 14C and 129I were measured by accelerator mass spectrometry (AMS) after chemical separation and purification of the samples. Mean 3H levels in precipitation (8.8 ± 3.4 TU) were found to be comparable to its levels in precipitation data in Germany. Rivers and small streams revealed similar mean 3H value (11.0 ± 3.3 TU) as in lake water (10.6 ± 3.4 TU). Variations in 3H concentrations in groundwater samples were observed and discussed. 14C levels in all groundwater samples were below the atmospheric natural level of 100 pMC indicating no anthropogenic input of radiocarbon. The 129I/127I isotopic ratios in all investigated water samples were in the order of 10−8 to 10−7, which is significantly higher than the pre-nuclear natural equilibrium isotopic ratio (∼1.5 × 10−12). In strong contrast to all other regional groundwaters, the Fuhrberger Feld groundwater has much higher values of 129I concentration and 129I/127I isotopic ratio close to the ones of surface water. The overall annual effective dose via ingestion for all nuclides in the investigated groundwater remains substantially below the reference dose level of 0.1 mSv a−1.

Historical record of nuclear activities from 129I in corals from the northern hemisphere (Philippines)

Iodine-129 is a long-lived fission product that is majorly released in human nuclear activities (HNA) such as nuclear bomb testing, nuclear fuel reprocessing, and nuclear accidents. It is a good environmental tracer and former measurements of 129I in corals from the southern hemisphere show the increasing trend of 129I concentrations in the marine environment caused by HNA. Here we show time series of 129I/127(stable)I isotopic ratios in two coral cores from the northern hemisphere (Philippines) and how these record 129I released from HNA in even greater, unprecedented detail. Corals were taken from the Pacific Ocean (Baler) and South China Sea (Parola) sides of the Philippines. We observed nearly identical peaks (129I/127I ∼ 31.5 × 10−12) in both the Baler and Parola records, each attributed to the year 1962 – the year with the highest recorded amount of 129I release from nuclear bomb testing. This 1962 129I bomb signal offers a new time marker that can be used to establish or confirm age models of corals, comparable to or possibly better than the well-known coral 14C bomb peak. We also observed nuclear fuel reprocessing and Chernobyl accident 129I signals in years 1977, 1980, and 1986, concurrently in Parola and with 9 to 11-year lags in Baler. This discrepancy in timing suggests that 129I was transported to the South China Sea and Pacific Ocean sides of the Philippines directly from the atmosphere and through prevailing ocean currents, respectively. Lastly, we observed surprisingly high 129I/127I isotopic ratios (i.e., 22.8 to 38.9 × 10−12) in the Parola record after the year 1996, which is in contrast to the decreasing trend observed in the Baler record and in published 129I releases of different HNA. These results possibly indicate the presence of unknown sources of 129I in the South China Sea region.

Influence of iodine supply on the radiation-induced DNA-fragmentation

The protective effect of stable iodide against radiation on thyroid cells was investigated. One physiological effect of stable iodine is well-rooted: stable iodine leads to a reduced thyroid uptake of radioactive iodine. This work wants to focus on an intrinsic effect of stable iodine by which DNA-damage in cells is prevented.To investigate this intrinsic effect thyroid cells (FRTL-5) were externally irradiated by use of a linear accelerator (LINAC) applying energy doses of 0.01 Gy–400 Gy and by incubation with various activity concentrations of 131I (0.1–50 MBq/ml for 24 h). We added stable iodine (NaI) to the cells prior to external irradiation and investigated the effect of the concentration of stable iodine (1, 5, 15 μg/ml). In order to clarify whether thyroid cells have a distinctive and iodine-dependent reaction to ionizing radiation, keratinocytes (HaCaT) without NIS were exposed in the same way. As indicators for the cellular reaction, the extent of DNA fragmentation was determined (Roche, Mannheim, Germany).Both cell types showed distinct ability for apoptosis as proven with camptothecin. The addition of “cold” iodine from 1 to 15 μg/ml without irradiation (“negative control”) did not change the response in both cell types. Plausibly, the radio-sensitivity of both cell types did increase markedly with increasing radiation dose but the radiation effect is diminished if iodine is added to the thyroid cells beforehand. The DNA-damage in thyroid cells after addition of cold iodine is reduced by a factor of 2–3. The skin cells did not show an significant change of radio-sensitivity depending on the presence of cold iodine. Elementary iodine possibly acts as a radical scavenger and thus markedly reduces the secondary radiation damage caused by the formation of cytotoxic radicals. This intrinsic radioprotective effect of iodine is seen only in cells with NIS.

Using smartphone as a motion detector to collect time-microenvironment data for estimating the inhalation dose

During the production of iodine-131 from neutron irradiated tellurium dioxide by the dry distillation, a considerable amount of 131I vapor is dispersed to the indoor air. People who routinely work at the production area may result in a significant risk of exposure to chronic intake by inhaled 131I. This study aims to estimate the inhalation dose for individuals manipulating the 131I at a radioisotope production. By using an application installed on smartphones, we collected the time-microenvironment data spent by a radiation group during work days in 2015. Simultaneously, we used a portable air sampler combined with radioiodine cartridges for grabbing the indoor air samples and then the daily averaged 131I concentration was calculated. Finally, the time-microenvironment data jointed with the concentration to estimate the inhalation dose for the workers. The result showed that most of the workers had the annual internal dose in 1÷6mSv. We concluded that using smartphone as a motion detector is a possible and reliable way instead of the questionnaires, diary or GPS-based method. It is, however, only suitable for monitoring on fixed indoor environments and limited the targeted people.

The seasonal fluctuations and accumulation of iodine-129 in relation to the hydrogeochemistry of the Wolf Creek Research Basin, a discontinuous permafrost watershed

The long lived radioisotope 129I is a uranium fission product, and an environmental contaminant of the nuclear age. Consequently, it can trace anthropogenic releases of 129I in watersheds, and has been identified as a potential means to distinguish water sources in discharge (Nimz, 1998). The purpose of this work was to identify the sources and mass input of 129I and trace the transport, partitioning and mass balance of 129I over time in a remote watershed. We monitored 129I and other geochemical and isotope tracers (e.g. δ14CDIC, δ13CDIC, δ2H, δ18O, etc.) in precipitation and discharge from the Wolf Creek Research Basin (WCRB), a discontinuous permafrost watershed in the Yukon Territory, Canada, and evaluated the use of 129I as a water end-member tracer. Radiocarbon and geochemical tracers of weathering show that discharge is comprised of (i) groundwater baseflow that has recharged under open system conditions, (ii) spring freshet meltwater that has derived solutes through closed-system interaction with saturated soils, and (iii) active layer drainage. The abundance of 129I and the 129I/127I ratio correlated with geochemical tracers suggests varying contributions of these three water end-members to discharge. The 129I concentration was highest at the onset of freshet, reaching 17.4×106 atoms/L, and likely reflects the lack of interaction between meltwater and organic matter at that time. This peak in 129I was followed by a decline over the summer to its lowest value. Mass balance calculations of the 129I budget show that the input to the watershed via precipitation is nearly one order of magnitude higher than the output suggesting that such arctic watersheds accumulate nearly 90% of the annual input, primarily in soil organic matter. Temporal variations in discharge 129I concentrations correlated with changes in discharge water sources suggesting that 129I is a promising hydrologic tracer, particularly when used in concert with other stable and radioisotopes.

Air concentration estimation of radionuclides discharged from Fukushima Daiichi Nuclear Power Station using NaI(Tl) detector pulse height distribution measured in Ibaraki Prefecture

ABSTRACTAir concentrations of 133Xe, 131I, 132I, 133I, 132Te, 134Cs, 136Cs, and 137Cs in the early stage of the Fukushima Daiichi Nuclear Power Station (FNPS1) accident were estimated for six locations in Ibaraki Prefecture from pulse height distributions measured with NaI(Tl) scintillation detectors continuously operated as a part of monitoring station systems. Air concentration of 133Xe in Ibaraki was estimated for the first time, which showed the maximum value of 150 kBq m−3 in the plume arrived at the southern part of Ibaraki around noon of 15 March 2011. The plume was found to consist mainly of noble gases without other nuclides at significant level and to correspond to the hydrogen explosion at Unit 3. Spatiotemporal distributions of 131I and other nuclides were discussed for the plumes detected during the periods of 15–16 and 20–21 March. Variations in radionuclide composition among the plumes and within each plume were also discussed.

Iodine-129, Iodine-127 and Cesium-137 in seawater from the North Sea and the Baltic Sea

In this study, new data are presented for the iodine isotopes (127I, 129I and their isotopic ratios) and Cesium (137Cs) in water samples of the North Sea and the Baltic Sea in 2005 and 2009. This study supplements and extends the study of Michel et al. (2012). Iodine isotopes were separated from their matrix by using an anion exchange method and were determined by applying ICP-MS and AMS. 137Cs in seawater was determined after cesium ion exchange procedure enrichment by gamma-spectrometry. The concentrations of 127I in seawater of the North and Baltic Sea are fairly constant in each Sea with averages of (44 ± 2) and (21 ± 1) ng g−1, respectively, depending on the salinity. However, large variations of 129I concentrations in these areas were detected, which decreased along the French, Belgian, Dutch, German, and Danish shores. 129I/127I isotope ratios in the Baltic Sea are about 10 times lower than in the North Sea in 2009. The highest isotopic ratios (2.7 × 10−6) was detected in the English Channel east of the nuclear reprocessing plant at Cap de la Hague. The results confirm the result of our early study that the sources of 129I in the North Sea are primarily the nuclear reprocessing facilities at Sellafield (UK) and La Hague (F), and that in the Baltic Sea the inflow of water from North Sea through the Danish Straits dominates the occurrence of 129I.In 2009, the activity concentration of 137Cs was at least 6 times higher in the Baltic Sea (37 Bq m−3) than in the North Sea (5.9 Bq m−3), due to release of 137Cs from sediments in the Baltic Sea, which were contaminated by the Chernobyl accident and – to a minor degree – the atmospheric explosions of atomic bombs. The results are discussed by comparing the results of our previous work and the current study demonstrating the continuing disequilibrium of 129I/127I atomic ratio in the environmental compartments.

Observation of radioactive iodine (131I, 129I) in cropland soil after the Fukushima nuclear accident

During the early stages of the Fukushima nuclear accident, the temporal variations of 131I deposited on the ground and of 131I accumulated in cropland soil were monitored at a fixed location in Japan. Moreover, concentrations of long-lived radioactive iodine (129I) in atmospheric deposits and soil were measured to examine the feasibility of retrospectively reconstructing 131I levels from the levels of accident-derived 129I. The exceptionally high levels of 131I in deposits and soil were attributed to rainfall-related deposition of radionuclides. In the crop field studied, the losses of deposited 131I and 129I due to volatilization were small. The atomic ratio 129I/131I in the topsoil corresponded to the same ratio in deposits. The 131I concentrations measured in the topsoil were very consistent with the 131I concentrations reconstructed from the 129I concentrations in the soil.

Iodine binding to humic acid

The rate of reactions between humic acid (HA) and iodide (I−) and iodate (IO3−) have been investigated in suspensions spiked with 129I at concentrations of 22, 44 and 88 μg L−1 and stored at 10 °C. Changes in the speciation of 129I−, 129IO3− and mixed (129I− + 129IO3−) spikes were monitored over 77 days using liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS). In suspensions spiked with 129I− 25% of the added I− was transformed into organic iodine (Org-129I) within 77 days and there was no evidence of 129IO3− formation. By contrast, rapid loss of 129IO3− and increase in both 129I− and Org-129I was observed in 129IO3−-spiked suspensions. However, the rate of Org-129I production was greater in mixed systems compared to 129IO3−-spiked suspensions with the same total 129I concentration, possibly indicating IO3−I− redox coupling. Size exclusion chromatography (SEC) demonstrated that Org-129I was present in both high and low molecular weight fractions of the HA although a slight preference to bond with the lower molecular weight fractions was observed indicating that, after 77 days, the spiked isotope had not fully mixed with the native 127I pool. Iodine transformations were modelled using first order rate equations and fitted rate coefficients determined. However, extrapolation of the model to 250 days indicated that a pseudo-steady state would be attained after ∼200 days but that the proportion of 129I incorporated into HA was less than that of 127I indicating the presence of a recalcitrant pool of 127I that was unavailable for isotopic mixing.

<sup>129</sup>I and <sup>137</sup>Cs in groundwater in the vicinity of Fukushima Dai-ichi nuclear power plant

This paper reports iodine (127I and 129I) and cesium (137Cs) isotope concentrations in groundwater of confined and unconfined aquifers in the vicinity of the Fukushima Dai-ichi nuclear power plant (FDNPP). 127I and 129I concentrations range from 2–13 μg/L and 5 × 107–8 × 1010 atom/L respectively, resulting in 129I/127I atomic ratios from 5 × 10–9 to 2 × 10–6. In all samples, 137Cs concentrations were below detection limit. The deep-sealed groundwater from the confined aquifer did not contain significant quantities of Fukushima-derived 129I compared to the groundwater in the unconfined aquifer. The minimal 129I/137Cs activity ratios in the groundwater are more than 2–500 times higher than the FDNPP source ratio. These data can be explained by rainwater infiltrating through the surface soils, with the more water-soluble 129I preferentially extracted into the aqueous phase and the 137Cs preferentially retained in the soil.

Estimating the impact from Fukushima in Southern Spain by 131I and Accelerator Mass Spectrometry detection of 129I

After the Fukushima accident, large amounts of radionuclides were discharged to the atmosphere. Some of them travelled long distances and were detected in places as far from Japan as Spain a few days after the accident. One of these radionuclides was 131I. Its isotope 129I (T1/2 = 15.7 × 106 years) was also expected to follow the same pathway. In this work, we present the results for the 129I concentration in the same atmospheric samples from Seville (Spain) where 131I activity was measured in 2011 by Baeza et al. (2012). 129I concentrations in aerosol and gaseous samples showed concentrations in the order of 104 and 105 atoms/m3, typically higher in the gaseous form with respect to the aerosol form. Also 129I in rainwater was measured, showing concentrations in the order of 108 atoms/L. The results show a very good agreement with the 131I profile, showing that, if background from other sources is not relevant, it is possible to estimate the impact of similar events years after them thanks to the sensitivity of techniques like Accelerator Mass Spectrometry.