129I Concentrations Research Articles

Water mass composition in Fram Strait determined from the combination of 129I and 236U: Changes between 2016, 2018, and 2019

Changes in the provenance and composition of waters exported from the Arctic Ocean have the potential to impact large-scale ocean circulation processes in the sub-polar North Atlantic. The main conveyor of waters from the Arctic Ocean to lower latitudes is the East Greenland Current (EGC), flowing southward through Fram Strait. It is therefore crucial to determine and monitor the composition of the EGC, a mixture of polar waters of different origins. Here we present a pilot study on the potential of the long-lived anthropogenic radionuclides 129I and 236U as tracers of the EGC water mass composition, based on a time series of 236U and 129I concentrations measured across Fram Strait in the years 2016, 2018, and 2019. The overall spatial distribution of 236U and 129I was similar among the three sampling years, but a decrease in concentration was observed in the upper water column of the EGC. The observed changes could only partly be attributed to the transient nature of the radionuclide signals, but instead pointed to changes in the EGC water mass composition. To investigate these changes, 236U and 129I were first combined in a mixing model featuring the endmembers expected in the upper EGC. We distinguished between Pacific Water (PAC), Atlantic Water advected from the Arctic Ocean (ATL), and Atlantic Water recirculating in Fram Strait (RAC). In 236U-129I tracer space, PAC and RAC showed similar tracer signatures, but were well distinguished from ATL. From 2016 to 2018/19, a decrease in the ATL fraction was evident for the upper EGC. Secondly, the respective combination of 236U and 129I with salinity showed differences in absolute water mass fractions, but similar temporal trends. Both suggested an increase in PAC of about 20% for the uppermost layer of the EGC (samples with potential densities below 26.5) and an increase in RAC of about 10−20 % for denser samples. 129I and 236U, in combination with salinity, were shown to be suitable tracers to investigate water mass composition in Fram Strait, with the advantage that they can distinguish Atlantic Water advected from the Arctic Ocean from that recirculating in Fram Strait.

Distribution of Anthropogenic 129I in the Western South China Sea and Its Application for Tracing the Sources and Movement of Pollution.

Anthropogenic 129I has been dispersed all over the world and could be utilized as an oceanographic tracer based on its conservative nature in the ocean. The first datasets of 129I and 127I were obtained by analysis of seawater of 36 water columns collected in the western South China Sea during August-September 2018. The measured 129I concentrations decreased with depth from (0.93-1.61) × 107 atoms/L in the upper 200 m to (0.04-0.14) × 107 atoms/L at 1500 m, indicating a clear anthropogenic source in the upper layer, mainly originated from the global fallout. The riverine input of the deposited 129I on the catchment area of the Mekong River is an important source besides the direct deposition in the seas. The water mass with high 129I from the Mekong River water moves to the east at 11°N by the North Nansha Current in the surface layer (2-25 m). The exponentially decreasing 129I level with depth indicates that the vertical dispersion of 129I from the upper to the lower layer was mainly through slow diffusion, and the deep water at more than 1500 m was not significantly contaminated by the upper layer water at least in the past 70 years.

Ultra-Sensitive Determination of Particulate, Gaseous Inorganic and Organic Iodine-129 and Iodine-127 in Ambient Air.

Atmospheric iodine cycling is of significance in climate change and environmental and health impacts. To better explore speciation transformation of atmospheric stable and radioactive iodine, an ultra-sensitive analytical method was established for determination of 129I and 127I in particulate, gaseous inorganic, and gaseous organic species, which was conducted with a self-designed cascade sampling apparatus, followed by their separation with a pyrolysis system and accelerator mass spectrometry and ICP-MS measurements. Combustion protocols for three sampling matrices and NaOH concentration for iodine trapping were optimized to achieve a safe analytical procedure with a high chemical yield of iodine. Based on the lowest concentrations of 129I and 127I, a suitable activated carbon product for adsorption of gaseous organic iodine was carefully selected. The detection limits of the three species were 0.30-2.21 ng m-3 for 127I and 0.05-0.22 × 105 atoms m-3 for 129I. This newly established method was successfully applied to analyze the levels and species of 129I and 127I in ambinet air from Xi'an, China, from May to August, 2020. Gaseous organic iodine was found to be the dominant species of 127I and 129I, accounting for about half of total iodine, and gaseous inorganic iodine and particulate iodine accounted for one-quarter each during the whole sampling period. Speciation variation of 129I and 127I indicates that speciation transformation apparently occurred at the turn of spring and summer, mainly between particulate and gaseous organic iodine. This study has implications on delicate tracing of the atmospheric behavior of iodine with long-lived anthropogenic 129I.

Time-series variations in 129I concentrations and 129I/137Cs ratios in suspended particulate matter collected in eastern Japan immediately after the 2011 nuclear accident in Fukushima, Japan

We have determined the hourly atmospheric concentrations of 129I in aerosols dispersed into the atmosphere by the nuclear accident at the Fukushima Daiichi Nuclear Power Plant (FD1NPP) on March 11, 2011. Data were obtained by measuring the quantity of 129I in suspended particulate matter (SPM) collected on filter tapes at 41 SPM monitoring stations in Fukushima and other prefectures in eastern Japan, including the metropolitan area of Tokyo and the surrounding area. After scrutiny, 500 out of 920 hourly SPM samples were determined to be reliable (i.e., devoid of cross-contamination), and these were subjected to further analysis and discussion. Based on the data from these samples, especially data from the four SPM sampling sites located close to the FD1NPP (Futaba, Naraha, Haramachi and Nihonmatsu), the time-series variations in the atmospheric concentration of 129I and the activity ratio of 129I/137Cs were reconstructed by using 137Cs concentration data in the literature. 129I and 137Cs were observed to be continuously and sometimes explosively dispersed into the atmosphere in aerosols transported by radioactive plumes from the FD1NPP. The highest activity concentrations of 129I and 137Cs were observed in the SPM sample at the Futaba SPM station (3.2 km west-northwest of the FD1NPP) at 14:00–15:00 on March 12 after the venting of Unit 1. Systematically high 129I/137Cs activity ratios were observed at the Futaba and Haramachi stations from March 12 to 14, suggesting that radioactive masses released from the FD1NPP during the first few days after the nuclear accident were relatively enriched in radioiodine. High activity ratios of 129I/137Cs were also measured starting on March 21 at Naraha (17.5 km south of FD1NPP) and from March 22–23 in the metropolitan area which must have been caused by a different type of emission event(s) on those days at the FD1NPP, as previously reported. The 129I data from this study are highly effective in the validation and elaboration of the modelling of the atmospheric dispersion of radioiodine. They further contribute to assessing the internal exposure due to inhalation of 131I estimated by means of such elaborate atmospheric diffusion models.

Evaluation of 131I transfer in the environment based on the available measurements made in Belarus after the Chernobyl accident

This study evaluates the 131I transfer from ground deposition to the human thyroid gland after the Chernobyl accident using measurements of 131I concentrations in 1,252 soil, 124 grass, and 136 cow's milk samples as well as 131I thyroid activity measured in 3,100 individuals included in the Belarusian-American cohort. The following parameters of an 131I environmental transfer model used to calculate thyroid doses were evaluated in this study: (i) the interception factor of 131I by pasture grass, which was described by a purely empirical equation, (ii) the removal rate of 131I from pasture grass due to weathering and growth dilution, estimated to be 0.0676 d−1 (half-life of 10.3 d), (iii) the removal rate of 131I from cow's milk, estimated to be 0.0686 d−1 (half-life of 10.1 d), and (iv) the transfer coefficient of 131I from feed to cow's milk, arithmetic mean ± standard deviation of (6.7 ± 8.7) × 10−3 d L−1 (median = 4.0 × 10−3 d L−1). The individual model-based and measurement-based 131I thyroid activities for the Belarusian-American cohort members were calculated using different starting points of 131I transfer in the chain ‘ground deposition’ → ‘vegetation’ → ‘cow's milk’ → ‘human thyroid’, i.e., the measured 131I concentrations in soil, grass, and cow's milk. De novo thyroid doses from 131I for the 3,100 cohort members were calculated in this study using measured 131I activity concentrations in soil, grass, and cow's milk and were compared with those estimated previously for the same individuals using model-based 131I activity concentrations. It was shown that the use of measured instead of model-based 131I concentrations, in general, did not improve the measurement-based thyroid dose estimates. This is likely to be because there was already a good generic data base for the parameters used in this assessment. This finding indicates that, although the measurements of environmental samples are essential to estimate the parameter values of the 131I transfer model, the individual measurements of 131I thyroid activity are the most valuable information for estimating individual thyroid doses.

Rapidly Increasing Artificial Iodine Highlights Pathways of Iceland-Scotland Overflow Water and Labrador Sea Water

Iceland-Scotland Overflow Water (ISOW) and Labrador Seawater (LSW) are major water masses of the lower Atlantic Meridional Overturning Circulation (AMOC). Therefore, the investigation of their transport pathways is important to understand the structure of the AMOC and how climate properties are exported from the North Atlantic to lower latitudes. There is growing evidence from Lagrangian model simulations and observations that ISOW and LSW detach from boundary currents and spread off-boundary, into the basin interior in the Atlantic Ocean. Nuclear fuel reprocessing facilities of Sellafield and La Hague have been releasing artificial iodine (129I) into the northeastern Atlantic since the 1960ies. As a result, 129I is supplied from north of the Greenland-Scotland passages into the subpolar region labelling waters of the southward flowing lower AMOC. To explore the potential of 129I as tracer of boundary and interior ISOW and LSW transport pathways, we analyzed the tracer concentrations in seawater collected during four oceanographic cruises in the subpolar and subtropical North Atlantic regions between 2017 and 2019. The new tracer observations showed that deep tracer maxima highlighted the spreading of ISOW along the flanks of Reykjanes Ridge, across fracture zones and into the eastern subpolar North Atlantic supporting recent Lagrangian studies. Further, we found that 129I is intruding the Atlantic Ocean at unprecedented rate and labelling much larger extensions and water masses than in the recent past. This has enabled the use of 129I for other purposes aside from tracing ISOW. For example, increasing tracer levels allowed us to differentiate between newly formed 129I-rich LSW and older vintages poorer in 129I content. Further, 129I concentration maxima at intermediate depths could be used to track the spreading of LSW beyond the subpolar region and far into subtropical seas near Bermuda. Considering that 129I releases from Sellafield and La Hague have increased or levelled off during the last decades, it is very likely that the tracer invasion will continue providing new tracing opportunities for 129I in the near future.

Bone Marrow Mesenchymal Stem Cell-Mediated Radiosensitive Promoter-Combined Sodium Iodide Symporter for the Treatment of Breast Cancer.

To develop genetically engineered bone marrow mesenchymal stem cells (BMSCs) that carries a radiotherapy gene to target triple-negative breast cancer (TNBC) and to evaluate the efficacy of radiation damage within the tumor microenvironment. The early growth response protein1 (Egr1)-human sodium iodide symporter (hNIS) gene was transfected into BMSCs by lentiviral transfection and the expression levels were evaluated by quantitative reverse transcription polymerase chain reaction. Transwell and adipogenesis and osteogenesis assays were performed to determine the targeting properties and adipogenic and osteogenic characteristics of the transgenic stem cells. The uptake of radioiodine and the efflux characteristics of the transgenic stem cells were determined by iodine uptake experiments. 131I-SPECT imaging was used to determine the characteristics of targeting to TNBC and to quantify the iodine uptake of transgenic stem cells in vivo. The effects of 131I treatment on BMSCs were characterized using tumor growth, immune cell infiltration, and tumor invasion endpoints based on immunohistochemistry and flow cytometry analysis of tumor samples. BMSCs-Egr1-hNIS cells abundantly express hNIS after radiation induction and are chemotactically attracted to TNBC tumors. Iodine uptake of BMSCs-Egr1-hNIS gradually increased with increasing induction concentrations and times. When the inductive concentration of 131I was >100 μCi/mL and lasted for 36 h, the rate of iodine uptake in cells increased. In vitro, the radioiodine quickly flowed out from cells within 20 min but in vivo, the rate of radioiodine loss was significantly slower and occurred over 24 h. After 131I therapy, tumor growth was inhibited, white blood cells infiltrated into tumor site and the levels of invasion-related cytokines significantly decreased. BMSCs-Egr1-hNIS-mediated 131I therapy can achieve precisely targeted radiotherapy to inhibit tumor growth, promote immune cell infiltration to the tumor sites, and reduce the invasiveness and metastasis characteristics of tumor cells.

129I in rainwater across Argentina

Concentrations of 127I and 129I in rainwater samples from several stations across Argentina (latitudes between 25° S and 55° S) were measured and analyzed for the assessment of distribution patterns and potential sources of 129I in the Southern Hemisphere. Measured 129I levels, clearly above those explainable by natural background and atmospheric nuclear weapons tests, can be understood by the injection into the Southern Hemisphere of 129I that had been discharged from nuclear fuel reprocessing plants in the Northern Hemisphere.

Migration of iodine-129 and iodine-127 in soils

Abstract To draw the balance of anthropogenic 129I input into European soils, the concentrations of 129I and 127I in seven soils from Lower Saxony were analyzed down to a depth of 250 cm. In comparison with pre-nuclear soils and Ukrainian soils, we detected a significant anthropogenic input of 129I. Considering the different time periods for the input of 129I and 127I it was possible to assess the dynamics of sorption processes which dominate migration and accumulation. Anthropogenic 129I was successfully used as a tracer for a clarification of the migration processes of trace elements in soils.

Occurrence, evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries, especially in big cities, like Beijing. However, the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear, and the processes driving evolution and degradation of heavy haze events are not well understood. Iodine isotopes (127I and 129I) as tracers were analyzed in time series aerosol samples collected from Beijing. It was observed that the 127I concentrations in aerosols peaked during the heavy haze events. The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles, which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events. Anthropogenic 129I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer. 129I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon. Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of 127I and 129I, i.e., iodine oxides intermediated secondary air particles, dust storm and mixed mode by both secondary air particles and dust storm induced processes.

Large seasonal fluctuations of groundwater radioiodine speciation and concentrations in a riparian wetland in South Carolina

Recent studies evaluating multiple years of groundwater radioiodine (129I) concentration in a riparian wetland located in South Carolina, USA identified strong seasonal concentration fluctuations, such that summer concentrations were much greater than winter concentrations. These fluctuations were observed only in the wetlands but not in the upland portion of the plume and only with 129I, and not with other contaminants of anthropogenic origin: nitrate/nitrite, strontium-90, technecium-99, tritium, or uranium. This unexplained observation was hypothesized to be the result of strongly coupled processes involving hydrology, water temperature, microbiology, and chemistry. To test this hypothesis, an extensive historical groundwater database was evaluated, and additional measurements of total iodine and iodine speciation were made from recently collected samples. During the summer, the water table decreased by as much as 0.7 m, surface water temperature increased by as much as 15 °C, and total iodine concentrations were consistently greater (up to 680%) than the following winter months. Most of the additional iodine observed in the summer could be attributed to proportional gains in organo-iodine, and not iodide or iodate. Furthermore, 129I concentrations were observed to be two-orders-of-magnitude greater at the bottom of the upland aquifer than at the top. A coupled hydrological and biogeochemical conceptual model is proposed to tie these observations together. First, as the surface water temperature increased during the summer, microbial activity was enhanced, which in turn stimulated the formation of mobile organo-I. Hydrological processes were also likely involved in the observed iodine seasonal changes: (1) as the water table decreased in summer, the remaining upland water entering the wetland was comprised of a greater proportion of water containing elevated iodine concentrations from the low depths, and (2) water flow paths in summer changed such that the wells intercepted more of the contaminant plume and less of the diluting rainwater (due to evapotranspiration) and streamwater (as the lower levels promote a predominantly recharging system). These results underscore the importance of coupled processes influencing contaminant concentrations, and the need to assess seasonal contaminant variations to optimize long-term monitoring programs of wetlands.

Development of a Simple Method for Determining the Absorbed Activity Concentration by the Thyroid Gland of Nuclear Medicine Staff

Introduction: The occupational safety of nuclear medicine staff working with radioactive iodine (131I) has always been a major concern in nuclear medicine. Since 131I is a volatile substance, it may enter the body during respiration and be absorbed by the thyroid gland of the hospital staff, causing major health problems. This study aimed to develop a simple method for determining the activity concentration of absorbed 131I in the thyroid gland of nuclear medicine staff, using a home-made anthropomorphic neck-thyroid phantom. Materials and Methods: For this purpose, 131I, with an activity of 370 kBq, was injected inside the thyroid glands of the phantom. The dose rate was measured by placing a portable detector on the thyroid gland at the surface of the neck phantom. The measurements were repeated for two months. Next, a calibration curve was drawn for iodine activity inside the thyroid versus dose rate at the neck surface. The calibration curve was then used to estimate the absorbed activity in the thyroid of the staff in one of the main hospitals of Shiraz, Iran. Finally, a new software program was developed for assessing and recording the activity concentration of 131I accumulated in the thyroid gland. Every day, the dose rate was measured by placing the detector on the neck of the staff. The dose rates were converted to activity concentrations inside the thyroid, using the mentioned calibration curve. Results: The results indicate that using the calibration factors for every detector, one can have the estimate of the radio-Iodine activity inside the thyroid. Conclusion: The method proposed in this study can be applied for internal contamination determination in normal working conditions and in accidents.

Records of iodine isotopes (129I, 127I) in the Barkol peat bog from northwest China and their sources, transport and preservation

The research on geochemical behaviors of iodine is significant for deep understanding of the source and distribution of iodine on the earth. However, as one of the most important sources, the ocean emissions and relative transport pathways of iodine, as well as the preservation after deposition are still not well known, especially in the arid areas of central Asia. A peat sediment core collected nearby Barkol Lake from northwest China was analyzed for iodine isotopes (127I and 129I). The observed high 127I concentration in the top 2 cm indicated a significant accumulation of iodine in the surface oxic conditions due to the continuous sources of incompletely decomposed organic matter. Dissociation of iodine into pore waters occurred once the anoxic conditions established beneath the surface by a serial reduction reaction during the degradation of organic matter. The temporal variation of anthropogenic 129I in the peat sediment recorded its sources and transport pathways. Besides the global fallout 129I during late 1950s and early 1960s, the significantly increased air releases from the European nuclear fuel reprocessing plants during 1975–1997 and the increased marine discharges since 1990s contributed the major portion of 129I in the peat core. The major transport pathway of 129I from the Europe was through Westerlies following the re-emission of the marine discharged 129I to the atmosphere, indicating a clearly ocean emitted iodine in the concerned central Asia.

Evaluation of radioiodine (129I) dissolution from sediment of a brackish lake beside a spent nuclear fuel reprocessing plant in Japan

Dissolution fluxes of stable (127I) and radioactive (129I) isotopes of iodine from a brackish lake sediment beside a spent nuclear fuel reprocessing plant in Japan were evaluated through two kinds of experiments: incubation using a sediment core sample for 24 h, and observation of 127I and 129I concentrations in sedimentary pore water. For 127I, the dissolution flux evaluated in the incubation experiment was comparable with that obtained from the vertical gradient of 127I concentration in pore water in the observation experiment. This suggests that degradation of organic matter in the surface sediment is an important source of dissolved 127I found in the water. For 129I, the dissolution flux estimated in the incubation experiment showed negative values, indicating the transfer of 129I to the sediment from the overlying water (i.e., absorption). Moreover, the flux evaluated from the observation experiment was positive. This result suggests that degradation of organic matter in the surface sediment is scarcely important to the supply of 129I from the sediment to the water in the studied lake. The dissolution flux of 129I estimated in the observation experiment was smaller than the absorption flux of 129I in the incubation experiment. This potentially indicates that the dissolution of sedimentary 129I does not significantly change 129I concentrations in the water and sediment of the lake. This hypothesis was consistent with previous research conducted for the studied lake.

Rapid and efficient autoclave digestion for the extraction of iodine-129 from urine samples

A new method was developed to extract 129I from urine samples and measure it using accelerator mass spectrometry (AMS). The samples were pre-treated in an autoclave with hydrogen peroxide and were then acidified with nitric acid, followed by the precipitation of iodine as silver iodide (AgI) for measurement by AMS. This new procedure is substantially faster than previous methods for the extraction of iodine from urine and results in less chemical waste. The efficiency and reproducibility of this method were evaluated by using 125I as a yield tracer, eventually giving a recovery above 99%. To achieve this, several iterations of the method were required. The method was then successfully applied to measure 129I/127I isotopic ratios and 129I concentrations in 25 human urine samples. The AMS results for 129I in urine ranged 3.3 × 106 atoms/L to 884 × 106 atoms/L and the isotope ratio (129I/127I) in human urine ranged from 7.38 × 10−12 to 3.97 × 10−10 with a median of 1.29 × 10−10. This new method will be useful for investigations into the sources of iodine in the human diet and their relative importance for iodine sufficiency.

Determination of iodine-129 in twenty soil and sediment reference materials

129I concentrations in twenty soil and sediment certified reference materials were presented for meeting the ever-growing demands in environmental, geological and nulcear sciences, including method development, calibration and quality control, etc.

Оценка распространения I-131 в окружающей среде и доз облучения населения Обнинска и его окрестностей от выбросов АО «НИФХИ им. Л.Я. Карпова»

Radiodine, I-131, is released into atmosphere during normal operation of the radiopharmaceutical production facility at the Karpov Institute of Physical Chemistry (NIFKhl) in Obninsk city. The paper presents analysis of monitoring of I-131 concentration in the air and radiation dose to the population of the Obninsk and its surroundings. To estimate annual radiation doses to the public I-131 concentration in the environment was first calculated. Data of radiation monitoring carried out in Obninsk were used to confirm the correctness of computed mean annual volume activity of I-131 in the air. Annual radioiodine doses to the public of Obninsk and its surroundings calculated exposed to radiation between 2015 and 2019 were within the range of 0.5 to 2.0 µSv/year, this level was considerably lower the limit set for the population living near the NIFKhI (300 µSv/year). The risk from radioiodine released into the atmosphere in the period from 2015-2019 was negligible (<10Е-6 year-1).

Bone marrow mesenchymal stem cell-mediated ultrasmall gold nanoclusters and hNIS gene synergize radiotherapy for breast cancer.

The human sodium iodide symporter (hNIS) can be linked to the downstream of radiation-sensitive early growth response protein1 (Egr1) promoter, and activated by the Egr1 following 131I treatment. However, the rapid outflow of 131I restricted the radiotherapy effect. To overcome this barrier, ultrasmall gold nanoclusters (usAuNCs) were used to enhance the radiotherapy efficacy of Egr1-hNIS for its radiation sensitization. In this work, we prepared "cell bomb" BMSCs carrying both GSH@AuNCs and Egr1-hNIS. We found that the "cell bomb" can target TNBC tumor and reach a maximum 131I concentration 9 h following 131I injection. Colony formation assay revealed that 131I, 131I combined with GSH@AuNCs could independently inhibit 39.5% and 66.4% of cell growth, respectively. Moreover, in vivo131I therapy further demonstrated that the growth of triple negative breast cancer (TNBC) was controlled by BMSC-Egr1-hNIS + AuNCs group, with relative volume inhibition percentages of 56.16% (compared with the control group) and 36.20% (compared with the BMSC-Egr1-hNIS group), respectively. To summarize, we successfully prepared BMSC-Egr1-hNIS carrying GSH@AuNCs to target TNBC which could synergistically improve the efficacy of hNIS gene therapy.

Reconstruction of radio-ecological model parameters based on the results of monitoring the radiation situation in Mazovia after the Chernobyl accident (based on the «Warsaw» scenario of the IAEA EMRAS project)

The paper analyzes the consistency of the input data of the radioecological model: the results of measurements of 137Cs and 131I concentrations in the atmosphere after the Chernobyl accident in Warsaw, the meteo-data on precipitation during the main radioactive fallout, the values of minimum 137Cs deposition densities on the territories of two dairy areas of Warsaw Area and Ostroleka Area in the central part of Mazovia. According to meteorological data in Warsaw Area during the period of radioactive fallout there were local rains. In Ostroleka Area, according to all weather stations, there was no rainfall during this period. In Warsaw Area, a minimum 137Cs deposition density of 1.3 kBq/m 2 with an error of less than 10% was found to be consistent with the “dry” deposition density of 137Cs (1.2 kBq/m 2 ) reconstructed by a simulated agroclimatic model based on atmospheric 137Cs measurements. This agreement, taking into account the amount of precipitation recorded at weather stations during the period of radioactive fallout and the significant, more than 10 times, dispersion of 137Cs fallout densities across the Warsaw Area, suggests that a homogeneous cloud-uniform fallout model is preferable for this region in radio-ecological modeling. For the Ostroleka Area, the variation in deposition densities of 137Cs was relatively small, at 3.2, and the estimated dry deposition density of 137Cs was 2.0-2.7 times lower than the measured minimum deposition densities in districts and settlements. This discrepancy, given the absence of precipitation recorded by all weather stations during the deposition period, led to the assumption that the 137Cs and 131I atmospheric concentrations in Ostroleka Area were 2-2.7 times higher than those in Warsaw Area. The adjustment of the 137Cs and 131I atmospheric concentrations in the Ostroleka Area for this region will be verified by measuring the 131I specific activity in milk under the Warsaw scenario.

Tracing the upwelling process in the northern Benguela upwelling system (nBUS) by 129I

New data on the presence of 129I in seawater in the Southern Hemisphere measured by Accelerator Mass Spectrometry (AMS) is presented. The samples were collected in 2014 along the Namibian coast during a cruise organised by the National Marine Information and Research Centre (NatMIRC), the national laboratories of the Ministry of Fisheries and Marine Resources (MFMR) in Namibia, and the IAEA Environment Laboratories (IAEA NAEL) in Monaco. The Benguela upwelling system is known as one of the most important marine upwelling regions in the world. Strong winds induce an offshore transport of surface seawater which is substituted by cool subsurface water inshore. As this water is nutrient-rich, which leads to high primary productivity, the Benguela upwelling system has a very important role as a fishing production area. The 129I concentrations in samples were between (0.66 ± 0.14) × 107 and (1.45 ± 0.30) × 107 atoms/kg. The highest 129I concentrations were found in the offshore surface samples. Deep-sea and inshore samples contained lower 129I concentrations, possibly as an effect of the upwelling process. A comparison with previously published studies suggests that the presence of 129I in the northern Benguela upwelling system (nBUS), is mainly due to the impact of nuclear weapons global fallout, without any evident impact of nuclear fuel reprocessing.