Radioactive impact of Fukushima accident on the Iberian Peninsula: evolution and plume previous pathway

Radioactivity of the atmospheric aerosols detected by CTBTO stations in Africa following the accident at the Fukushima Daiichi nuclear power plant

Radionuclides from the reactor accident Fukushima Daiichi nuclear power plant were observed in the airborne aerosols at CTBT International Monitoring System (IMS) stations (MRP43, CMP13) in Africa. The maximum activity concentrations in the air measured in Mauritania were 186.44 10-6 Bq.m-3, 264.16 10-6 Bq.m-3 and 1269.94 10-6 Bq.m-3 for 134Cs, 137Cs and 131I respectively, and in Cameroon 16.42 10-6 Bq.m-3, 25.53 10-6 and 37.58 10-6 Bq.m-3 respectively for 134Cs, 137Cs and 131I. The activity ratio of 134Cs/137Cs is almost constant throughout the period of time relevant to this study due to their long half-lives of 30.2 years for 137Cs and 2.06 years for 134Cs. Whereas the 131I/137Cs activity ratio varies in time according to the radioactive decay with a half-live of 8.06 days for 131I and different removal rates of both radionuclides from the atmosphere during transport. The EMAC atmospheric chemistry-general circulation was used to simulate the emission and transport of the isotope 137Cs and map the deposition of the 137Cs deposition over Africa.

Deposition of Fukushima nuclear power plant accident-derived radiocesium in the soils of Jeju Island, Korea, and evidence for long- and short-lived radionuclides in rainwater

In this study, we investigated the concentrations of Fukushima nuclear power plant accident (FNPPA)-derived radiocesium (¹³⁴Cs, ¹³⁷Cs) deposited in the topsoil of Jeju Island, Korea. We also evaluated the soil inventories of radionuclides and compared the concentrations deposited by rainwater and fallout. We present the first evidence of FNPPA-derived radionuclides directly entering the environment of Jeju Island. In the case of FNPPA-derived ¹³⁴Cs in soil, only a trace amount was identified in the surface layer (1 cm depth), whereas ¹³⁷Cs derived from past atmospheric deposition of nuclear testing were detected along with those derived from the nuclear power plant accident. The total measured radiocesium (¹³⁴Cs + ¹³⁷Cs) indicates that although the value obtained from soils was slightly lower, both values were within the same order of magnitude. Of the FNPPA-derived radiocesium deposited in the soil, the impact from April 2011 was the largest at most sampling sites indicating that the radioactive plume directly covered Jeju Island. Furthermore, a variety of long- and short-lived gamma-emitting radionuclides were detected in the rainwater samples collected on April 7, 2011. Among them, short-lived radionuclides such as ¹⁴⁰La, ^110mAg, ⁹⁵Nb, ¹²⁵Sb, ¹¹³Sn, ¹²⁹Te, ^129mTe, ¹³²Te, ¹³²I, and ¹³⁶Cs, were observed. The findings of this study provide evidence for the direct effects of FNPPA-derived radionuclides in Jeju Island. This is the first location in Korea and the first in the entire East Asian region, excluding Japan that is confirmed to have been directly affected FNPP accident.

Dispersion and ground deposition of radioactive material according to airflow patterns for enhancing the preparedness to N/R emergencies

The intent of minimizing the impact of the large amount of radioactive material potentially released into the atmosphere in a nuclear event implies preparedness activities. In the early phase and in absence of field observations, countermeasures would largely rely on a previous characterization of the transport and dispersion of radioactive particles and the potential levels of radioactive contamination. This study presents a methodology to estimate the atmospheric transport, dispersion and ground deposition patterns of radioactive particles. The methodology starts identifying the main airflow directions by means of the air mass trajectories calculated by the HYSPLIT model, and, secondly, the dispersion and the ground deposition characteristics associated with each airflow pattern by running the RIMPUFF atmospheric dispersion model. From the basis of these results, different products can be obtained, such as the most probable transport direction, spatial probability distribution of deposition and the geographical probability distribution of deposition above certain predefined threshold. The method is trained on the HYSPLIT trajectories and RIMPUFF simulations during five consecutive years (2012-2016) at the Almaraz Nuclear Power Plant, in Spain. 3644 forward air mass trajectories were calculated (at 00 and 12 UTC, and with duration of 36 h). Eight airflow patterns were identified, and within each pattern, the persistent days, i.e. those days in which trajectories at 00 and 12 UTC grouped into the same airflow pattern, were extracted to simulate the atmospheric dispersion and ground deposition following a hypothetical ISLOCA accident sequence of 35 h. In total, 833 simulations were carried out, in which ground contamination was estimated at cell level on a non-homogeneous geographical grid spacing up to 800 km from Almaraz. The corresponding outcomes show a large variability in the area covered and in deposition values between airflow patterns, which provide comprehensive and oriented information and resources to decision makers to emergency management.

From floodplain to aquatic sediments: Radiogeochronological fingerprints in a sediment core from the mining impacted Sancho Reservoir (SW Spain)

The Sancho Reservoir (SW Spain) was built in 1962, about the time of maximum ¹³⁷Cs fallout, and it has been affected by acid mine drainage (AMD) particularly since the mining cease in 2001. This is a unique scenario for studying the radiogeochronological fingerprints in AMD-affected sediments deposited over the former flood plain. A sediment core sampled in 2011 was analysed for bulk density, ¹³⁷Cs, ²³⁹Pu, ²⁴⁰Pu, ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²³⁴Th (²³⁸U) and ⁴⁰K, and studied with various radiometric dating models. Bulk density revealed unsteady compaction and likely depositional events. The activity concentrations of ²²⁶Ra, ²²⁸Ra, ²³⁴Th (²³⁸U) and ⁴⁰K were uniform down-core, but declining overall in the upper 0-25cm, revealing changes in provenance except for ²³⁸U, which increased in the top 10cm likely due to its supply by AMD. The AMD fingerprint was also found in the ^239+240Pu/¹³⁷Cs activity ratio, which increased in the top sediment layers. The ¹³⁷Cs and ^239+240Pu profiles show well defined peaks at the same depth, with inventories being about four times higher than the expected integrated atmospheric deposition in the area. The unsupported ²¹⁰Pb (²¹⁰Pb_exc) showed a complex non-monotonic profile interrupted at several sections, particularly around the ¹³⁷Cs peak. The whole dataset cannot be interpreted in terms of continuous sedimentation processes. Based upon correlated features in the bulk density and ²¹⁰Pb_exc profiles, a series of depositional events (likely linked to peaks in the rainfall records) have been identified in the core. These events date back to the period comprised since the construction of the dam until its increase in height in 1972, which likely displaced upstream the main depositional area of riverine loads, as inferred from sediment trap data. The CRS (with a reference date) and (a piecewise) CIC models have been used for complementing and discussing the chronology.

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.

Fukushima Daiichi Nuclear Plant accident: Atmospheric and oceanic impacts over the five years

The Fukushima Daiichi Nuclear Plant (FDNPP) accident resulted in huge environmental and socioeconomic impacts to Japan. To document the actual environmental and socioeconomic effects of the FDNPP accident, we describe here atmospheric and marine contamination due to radionuclides released from the FDNPP accident using papers published during past five years, in which temporal and spatial variations of FDNPP-derived radionuclides in air, deposition and seawater and their mapping are recorded by local, regional and global monitoring activities. High radioactivity-contaminated area in land were formed by the dispersion of the radioactive cloud and precipitation, depending on land topography and local meteorological conditions, whereas extremely high concentrations of (131)I and radiocesium in seawater occurred due to direct release of radioactivity-contaminated stagnant water in addition to atmospheric deposition. For both of atmosphere and ocean, numerical model simulations, including local, regional and global-scale modeling, were extensively employed to evaluate source terms of the FDNPP-derived radionuclides from the monitoring data. These models also provided predictions of the dispersion and high deposition areas of the FDNPP-derived radionuclides. However, there are significant differences between the observed and simulated values. Then, the monitoring data would give a good opportunity to improve numerical modeling.

The determination of Fukushima-derived cesium-134 and cesium-137 in Japanese green tea samples and their distribution subsequent to simulated beverage preparation

Health Canada's Radiation Protection Bureau has identified trace quantities of (134)Cs and (137)Cs in commercially available green tea products of Japanese origin. Referenced to March 11, 2011, the activity ratio ((134)Cs/(137)Cs) has been determined to be 1:1, which supports an origin from the Fukushima Dai-ichi Nuclear Power Plant accident. The upper limits of typical tea beverage preparation conditions were applied to the most contaminated of these green tea samples to determine the proportion of radiocesium contamination that would be available for human consumption. The distribution of radiocesium among the components of the extraction experiments (water, residual tea solid, and filter media) was determined by both conventional and Compton-suppressed gamma spectroscopy. The latter aided tremendously in providing a more complete radiocesium distribution profile, particularly for the shorter-lived (134)Cs. Cesium extraction efficiencies of 64 ± 7% and 64 ± 5% were determined based on (134)Cs and (137)Cs, respectively. Annual, effective dose estimates from ingestion of (137)Cs and (134)Cs (1.8-3.7 μSv), arising from the consumption of tea beverages prepared from the most contaminated of these samples, are insignificant relative to both total (∼ 2.4 mSv) and ingested (∼ 0.28 mSv) annual effective doses received from naturally occurring radioactive sources. As such, there is no health concern arising from the consumption of green tea beverages contaminated with radiocesium at the levels encountered in this study.

Predictability of the dispersion of Fukushima-derived radionuclides and their homogenization in the atmosphere

Long-range simulation of the dispersion of air pollutants in the atmosphere is one of the most challenging tasks in geosciences. Application of precise and fast numerical models in risk management and decision support can save human lives and can diminish consequences of an accidental release. Disaster at Fukushima Daiichi nuclear power plant has been the most serious event in the nuclear technology and industry in the recent years. We present and discuss the results of the numerical simulations on dispersion of Fukushima-derived particulate (131)I and (137)Cs using a global scale Lagrangian particle model. We compare concentrations and arrival times, using two emission scenarios, with the measured data obtained from 182 monitoring stations located all over the Northern Hemisphere. We also investigate the homogenization of isotopes in the atmosphere. Peak concentrations were predicted with typical accuracy of one order of magnitude showing a general underestimation in the case of (131)I but not for (137)Cs. Tropical and Arctic plumes, as well as the early detections in American and European midlatitudes were generally well predicted, however, the later regional-scale mixing could not be captured by the model. Our investigation highlights the importance of the parameterization of free atmospheric turbulence.

An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident

Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology.

Study of ⁷Be and ²¹⁰Pb as radiotracers of African intrusions in Malaga (Spain)

The relationship between the particulate matter in the atmosphere of Malaga and the origin of air masses with special attention to African intrusions was analyzed. The concentrations of PM10 and the activities of some radionuclides ((7)Be and (210)Pb) as tracers of these intrusions are discussed. The origin of these radiotracers is completely different. (210)Pb is a good tracer of air masses traveling close to the ground and come from inland areas. On the other hand, the production of (7)Be is very low in the vicinity of the Earth's surface, and increases with altitude, making it a great tracer of stratospheric air masses in the troposphere. Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of (7)Be and (210)Pb in aerosols at Malaga (36° 43' 40″ N; 4° 28' 8″ W) for the period 2009-2011 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory. The average concentration values of (7)Be and (210)Pb over the 3-year period have been found to be 5.05 and 0.55 mBq m(-3), respectively, with mean aerosol mass concentration of 53.6 μg m(-3). Taking into account the outbreaks of the daily values limits of PM10 in the study period (2009-2011), the origin of air masses is studied to explain three different situations of both radionuclides (7)Be and (210)Pb: 1) high concentrations of (7)Be and low concentrations of (210)Pb; 2) high concentrations of (210)Pb and low concentrations of (7)Be and 3) high concentrations of (7)Be and (210)Pb.

Trans-oceanic transport of 137Cs from the Fukushima nuclear accident and impact of hypothetical Fukushima-like events of future nuclear plants in Southern China

A Lagrangian model was adopted to assess the potential impact of (137)Cs released from hypothetical Fukushima-like accidents occurring on three potential nuclear power plant sites in Southern China in the near future (planned within 10 years) in four different seasons. The maximum surface (0-500 m) (137)Cs air concentrations would be reached 10 Bq m(-3) near the source, comparable to the Fukushima case. In January, Southeast Asian countries would be mostly affected by the radioactive plume due to the effects of winter monsoon. In April, the impact would be mainly on Southern and Northern China. Debris of radioactive plume (~1 mBq m(-3)) would carry out long-range transport to North America. The area of influence would be the smallest in July due to the frequent and intense wet removal events by trough of low pressure and tropical cyclone. The maximum worst-case areas of influence were 2382000, 2327000, 517000 and 1395000 km(2) in January, April, July and October, respectively. Prior to the above calculations, the model was employed to simulate the trans-oceanic transport of (137)Cs from the Fukushima nuclear accident. Observed and modeled (137)Cs concentrations were comparable. Sensitivity runs were performed to optimize the wet scavenging parameterization. The adoption of higher-resolution (1° × 1°) meteorological fields improved the prediction. The computed large-scale plume transport pattern over the Pacific Ocean was compared with that reported in the literature.

Release, deposition and elimination of radiocesium ((137)Cs) in the terrestrial environment

Radionuclide contamination in terrestrial ecosystems has reached a dangerous level. The major artificial radionuclide present in the environment is (137)Cs, which is released as a result of weapon production related to atomic projects, accidental explosions of nuclear power plants and other sources, such as reactors, evaporation ponds, liquid storage tanks, and burial grounds. The release of potentially hazardous radionuclides (radiocesium) in recent years has provided the opportunity to conduct multidisciplinary studies on their fate and transport. Radiocesium's high fission yield and ease of detection made it a prime candidate for early radio-ecological investigations. The facility setting provides a diverse background for the improved understanding of various factors that contribute toward the fate and transfer of radionuclides in the terrestrial ecosystem. In this review, we summarize the significant environmental radiocesium transfer factors to determine the damaging effects of radiocesium on terrestrial ecosystem. It has been found that (137)Cs can trace the transport of other radionuclides that have a high affinity for binding to soil particles (silts and clays). Possible remedial methods are also discussed for contaminated terrestrial systems. This review will serve as a guideline for future studies of the fate and transport of (137)Cs in terrestrial environments in the wake of the Fukushima Nuclear Power Plant disaster in 2011.

Radioactive contamination of pine (Pinus sylvestris) in Krasnoyarsk (Russia) following fallout from the Fukushima accident

Following the Fukushima accident in March 2011, samples of pine trees (Pinus sylvestris) were collected from three sites near the city of Krasnoyarsk (Siberia, Russia) during 2011-2012 and analyzed for artificial radionuclides. Concentrations of Fukushima-derived radionuclides in the samples of pine needles in April 2011 reached 5.51 ± 0.52 Bq kg(-1)(131)I, 0.92 ± 0.04 Bq kg(-1)(134)Cs, and 1.51 ± 0.07 Bq kg(-1)(137)Cs. An important finding was the detection of (134)Cs from the Fukushima accident not only in the pine needles and branches but also in the new shoots in 2012, which suggested a transfer of Fukushima cesium isotopes from branches to shoots. In 2011 and 2012, the (137)Cs/(134)Cs ratio for pine needles and branches collected in sampling areas Krasnoyarsk-1 and Krasnoyarsk-2 was greater than 1 (varying within a range of 1.2-2.6), suggesting the presence of "older", pre-Fukushima accident (137)Cs. Calculations showed that for pine samples growing in areas of the Krasnoyarskii Krai unaffected by contamination from the nuclear facility, the activity of the Fukushima-derived cesium isotopes was two-three times higher than the activity of the pre-accident (137)Cs.

Effect of the duration time of a nuclear accident on radiological health consequences

This study aimed to quantify the effect of duration time of a nuclear accident on the radiation dose of a densely populated area and the resulting acute health effects. In the case of nuclear accidents, the total emissions of radioactive materials can be classified into several categories. Therefore, the release information is very important for the assessment of risk to the public. We confirmed that when the duration time of the emissions are prolonged to 7 hours, the concentrations of radioactive substances in the ambient air are reduced by 50% compared to that when the duration time of emission is one hour. This means that the risk evaluation using only the first wind direction of an accident is very conservative, so it has to be used as a screening level for the risk assessment. Furthermore, it is judged that the proper control of the emission time of a nuclear accident can minimize the health effects on residents.

Estimation of internal exposure of the thyroid to (131)I on the basis of (134)Cs accumulated in the body among evacuees of the Fukushima Daiichi Nuclear Power Station accident

Namie Town was heavily contaminated by the Fukushima Daiichi Nuclear Power Station accident. The thyroid equivalent dose for residents who lived in Namie was estimated using results of whole body counting examinations which were carried out by the Japan Atomic Energy Agency a few months after the nuclear accident. Photon peaks of (131)I and (134)Cs were previously measured by the authors using a NaI(Tl) scintillation spectrometer and that information was used to estimate the (131)I/(134)Cs activity ratio of total intake in the present study. The maximum values of (131)I/(134)Cs activity ratio corresponding to thyroid uptake factors of 0.3, 0.1 and 0.03 were evaluated to be 0.9, 2.6 and 8.7, respectively. The maximum value of the (131)I/(134)Cs activity ratio was used to obtain the most conservative thyroid equivalent dose estimation. The maximum internal exposure of the thyroid to (131)I on the basis of (134)Cs accumulated in the body measured by the whole body counter was estimated to be 18mSv. This value was much smaller than 50mSv that the International Atomic Energy Agency recommends as the dose at which exposed persons should take stable iodine tablets.

An overview of Fukushima radionuclides measured in the northern hemisphere

The Great East Japan Earthquake and tsunami on March 11, 2011 resulted in the tragic accident at the Fukushima Nuclear Power Plant (NPP) and subsequently uncontrolled release of radioactive contaminants into the atmosphere. This review article attempts to compile and interpret data collected by various national and international monitoring networks in response to the Fukushima releases across the northern hemisphere. The majority of the releases occurred during the period March 12-22 with a maximum release phase from March 14-17, 2011. The radioactivity released was dominated by volatile fission products including isotopes of the noble gases (xenon and krypton), iodine, cesium, and tellurium. The radioactive gases and particles released in the accident were dispersed over the middle latitudes of the entire northern hemisphere and for the first time also measured in the southern Hemisphere. Isotopes of iodine and cesium were detected in air, water, milk and food samples collected across the entire northern hemisphere. Elevated levels of fission products were detected from March to May 2011 at many locations over the northern hemisphere. This article focuses on the most prevalent cesium and iodine isotopes, but other secondary isotopes are also discussed. Spatial and temporal patterns and differences are contrasted. The activity ratios of (131)I/(137)Cs and (134)Cs/(137)Cs measured at several locations are evaluated to gain an insight into the fuel burn-up, the inventory of radionuclides in the reactor and the isotopic signature of the accident. It is important to note that all of the radiation levels detected outside of Japan have been very low and are well below any level of public and environmental hazard.

Anthropogenic radionuclides in the atmosphere observed at Tsukuba: characteristics of the radionuclides derived from Fukushima

During a serious accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), a huge quantity of radionuclides was released into the atmosphere and ocean. We measured anthropogenic radionuclides in surface air at Tsukuba, about 170 km from the FDNPP. On March 15, 2011, we detected the radioactivity released from the Fukushima accident in air samples at Tsukuba. The major radionuclides that we observed were radioiodine ((131)I, (132)I, (133)I) and radiocesium ((134)Cs, (136)Cs, (137)Cs). This radioiodine consisted of gaseous and particulate forms; the percentage of particulate (131)I in the total (131)I ranged from 0 to 86%. The percentage of the particulate (131)I to the total (131)I increased on the arrival of the plumes from major emissions of the FDNPP. After activities of the radionuclides attained the maximum on March 15, 2011, the FDNPP-derived radionuclides decreased rapidly in surface air. The activity median aerodynamic diameter of (131)I-bearing particles was 0.7 μm, while those of (134)Cs- and (137)Cs-bearing particles were larger than 1 μm. Large variations of ratios of (131)I/(137)Cs, (132)Te/(137)Cs, and (99)Mo ((99m)Tc)/(137)Cs (all involving different elements) suggest that the behaviors of these radionuclides in the atmosphere, including the processes of their emission, differed each other.

Spatial distribution and vertical migration of (137)Cs in soils of Belgrade (Serbia) 25 years after the Chernobyl accident

In this study, the specific activity of (137)Cs was determined by gamma-ray spectrometry in 72 surface soil samples and 11 soil profiles collected from the territory of Belgrade 25 years after the Chernobyl accident. Based on the data obtained the external effective gamma dose rates due to (137)Cs were assessed and geographically mapped. The influence of pedogenic factors (pH, specific electrical conductivity, cation exchange capacity, organic matter content, soil particle size and carbonate content) on the spatial and vertical distribution of (137)Cs in soil was estimated through Pearson correlations. The specific activity of (137)Cs in surface soil samples ranged from 1.00 to 180 Bq kg(-1), with a mean value of 29.9 Bq kg(-1), while in soil profiles they ranged from 0.90 to 58.0 Bq kg(-1), with a mean value of 15.3 Bq kg(-1). The mean external effective gamma dose at 1 m above the ground due to (137)Cs in the soil was calculated to be 1.96 nSv h(-1). Geographic mapping of the external effective gamma dose rates originating from (137)Cs revealed much higher dose rates in southern parts of Belgrade city and around the confluence of the Sava and Danube. Negative Pearson correlation coefficients were found between pH, cation exchange capacity and (137)Cs specific activity in surface soil. There were positive correlations between organic matter and (137)Cs specific activity in surface soil; and between specific electrical conductivity, organic matter, silt content and (137)Cs specific activity in soil profiles.

Activity measurement of gamma-ray emitters in aerosol filters exposed in Lithuania, in March-April 2011

Two aerosol sampling stations in Lithuania were simultaneously used for assessing consequences of the accident at the Fukushima Dai-ichi nuclear power plant. The maximum activity concentrations of (129 m)Te, (131)I, (134)Cs and (137)Cs were 0.59 ± 0.06, 3.5 ± 0.3, 0.90 ± 0.08, 0.90 ± 0.07 mBq m(-3) at station #1 in Vilnius, and 0.29 ± 0.03, 1.0 ± 0.1, 0.41 ± 0.04, 0.41 ± 0.0 4 mBq m(-3) at station #2 in northeastern part of Lithuania, respectively.

Artificial radioactivity in environmental media (air, rainwater, soil, vegetation) in Austria after the Fukushima nuclear accident

Several environmental media in Austria were monitored for artificial radionuclides released during the Fukushima nuclear accident. Air (up to 1.2 mBq/m(3) particulate (131)I) and rainwater (up to 5.2 Bq/L (131)I) proved to be the media best suited for the environmental monitoring, allowing also a temporal resolution of the activity levels. Significant regional differences in the wet deposition of (131)I with rain could be observed within the city of Vienna during the arrival of the contaminated air masses. Forward-trajectory analysis supported the hypothesis that the contaminated air masses coming from the northwest changed direction to northeast over Northern Austria, leading to a strong activity concentration gradient over Vienna. In the course of the environmental monitoring of the Fukushima releases, this phenomenon-significant differences of (131)I activity concentrations in rainwater on a narrow local scale (8.1 km)-appears to be unique. Vegetation (grass) was contaminated with (131)I and/or (137)Cs at a low level. Soil (up to 22 Bq/kg (137)Cs) was only affected by previous releases (nuclear weapon tests, Chernobyl). Here, also significant local differences can be observed due to different deposition rates during the Chernobyl accident. The effective ecological half-lives of (137)Cs in soil were calculated for four locations in Austria. They range from 7 to 30 years. No Austrian sample investigated herein exceeded the detection limit for (134)Cs; hence, the Fukushima nuclear accident did not contribute significantly to the total radiocesium inventory in Austrian environmental media. The levels of detected radioactivity were of no concern for public health.

Arrival of radionuclides released by the Fukushima accident to Tenerife (Canary Islands)

Two weeks after the accident at the Fukushima-Daichi nuclear power plant, 131I, 137Cs and 134Cs activities were measured in two different stations located in Tenerife (Canary Islands), situated at 300 (FIMERALL) and 2400 (IZAÑA) m.a.s.l, respectively. Peak measured activity concentrations were: 1.851 mBq/m3 (131I); 0.408 mBq/m3 (137Cs) and 0.382 mBq/m3 (134Cs). The activities measured at the FIMERALL station were always higher than at IZAÑA station, suggesting that the radioactive plume arrived to the island associated with low altitude air masses. Simulations of potential dispersion of the radioactive cloud (137Cs) after the nuclear accident in reactor Fukushima I show that radioactive pollution reached remote regions such as the Canary Islands in the Eastern subtropical North Atlantic. The corresponding effective dose to the local population was 1.17 nSv, a value less than one millionth of the annual limit for the general public. Therefore, there was no risk to public health.

Comparison of radioactivity data measured in PM10 aerosol samples at two elevated stations in northern Italy during the Fukushima event

The follow-up of Fukushima radioactive plume resulting from the 11th March 2011 devastating tsunami is discussed for two Italian stations in the northern Apennines: Mt. Cimone (Modena) and Montecuccolino (Bologna). Radioactivity data collected at both stations are described, including comparison between local natural background of airborne particulate and artificial radioactivity referable to the arrival of the radioactive plume and its persistence and evolution. Analysis of back-trajectories was used to confirm the arrival of artificial radionuclides following atmospheric transport and processing. The Fukushima plume was first detected on 3rd April 2011 when high volume sampling revealed the presence of the artificial radionuclides (131)I, (137)Cs and (134)Cs. The highest activity concentrations of these nuclides were detected on 5th April 2011 at the Montecuccolino site. Fukushima radioactivity data at the two stations were usually comparable, suggesting a good vertical mixing of the plume; discrepancies were occasional and attributed to different occurrence of wet removal, typically characterized by a scattered spatial pattern. To understand the relevance to the local population of the extra dose due to the Fukushima plume, atmospheric activities of the related artificial nuclides were compared to those of the main natural radionuclides in ambient particulate, and found to be lower by over one order of magnitude. Radiation doses referable to Fukushima, maximized for a whole year occurrence at the highest activity level observed at our stations in the weeks affected by the Japanese plume, were estimated at 1.1 μSv/year.

Environmental radioactivity analyses in Italy following the Fukushima Dai-ichi nuclear accident

Following the Fukushima power plants accident on the 11th March 2011, the radioactivity monitoring programme at the Italian ENEA research centres was activated in order to detect the possible new input of radionuclides through atmospheric transport and precipitation. Measurements of (131)I and (134,137)Cs were carried out on atmospheric particulate, atmospheric deposition, seawater and mussels and sheep milk. In the daily samples of air particulate, (131)I was detectable between March 28 and April 12, with extremely low concentrations (<1 mBq m(-3); the detection limit for (131)I was ~0.2 mBq m(-3)) while Cs isotopes were always below the detection limit (<0.2 mBq m(-3)). The two main episodes of (131)I atmospheric deposition were registered in La Spezia research centre, around March 28 and April 15, reaching values of 17.8 ± 1.1 and 8.0 ± 2.5 Bq m(-2) respectively; maximum values of (134)Cs and (137)Cs were 0.11 ± 0.03 and 0.17 ± 0.02 Bq m(-2), respectively, detected in Brasimone research centre in April (reference date April 15). Mussels and seawater were collected in the Gulf of La Spezia: only mussels after the main (131)I deposition, on March 28, contained a measurable, although very small, amount of (131)I (0.18 ± 0.05 Bq kg(-1), detection limit (131)I = 0.03 Bq kg(-1) wet weight - soft parts). The (131)I was also detected in sheep milk in Rome (Casaccia research centre) until May 5, showing a maximum concentration of 4.9 ± 0.4 Bq L(-1). As for other European Countries for which data are available, activity levels remain of no concern for public health.

Indicators of the Fukushima radioactive release in NW Romania

As a result of the Fukushima nuclear release, (131)I was found in different environmental media (rainwater, sheep and cow milk, herbage, sheep meat and thyroid tissue) in north-west Romania. On April 4, 2011 a maximum value of 1.40 ± 0.21 Bq/L in (131)I activity was found in rainwater obtained from the Arad region. The obtained value corresponded with the maximum of (131)I concentration in air, as measured by Toma et al. (2011) for the Piteşti area. One day later, sheep milk from the Cluj area was found to contain a maximum activity of 9.22 ± 0.95 Bq/L. A value of 0.85 ± 0.07 μSv was calculated as the total monthly effective dose received by the population as a result of the ingestion of sheep milk and sheep meat contaminated with (131)I. Only rainwater samples contained (134)Cs and (137)Cs at levels close to minimum detectable activity. Since the determined values could be influenced by Chernobyl (137)Cs, the (137)Cs concentrations are subject to uncertainty. The radioiodine transfer coefficients (Fm) and the concentration ratio (CR) from herbage to sheep milk, as well as sheep meat, from the Cluj-Apahida area are also presented.

Fukushima fallout at Milano, Italy

The radionuclides (131)I, (137)Cs and (134)Cs were observed in the Milano region (45°) of Italy early after the nuclear accident in Fukushima, Japan. Increased atmospheric radioactivity was observed on an air filter taken on 30 March 2011, while the maximum activity of 467 μBq m(-3) for (131)I was recorded at April 3-4, 2011. The first evidence of Fukushima fallout was confirmed with (131)I and (137)Cs measured in precipitation at two sampling sites at Milano on 28 March, 2011, with the concentrations of (131)I and (137)Cs in the rainwater equal to 0.89 Bq L(-1) and 0.12 Bq L(-1), respectively. A sample of dry deposition that was collected 9 days after the first rainfall event of 27-28 March, 2011 showed that the dry deposition was more effective in the case of (137)Cs than it was for (131)I, probably because iodine was mainly in gaseous form whereas caesium was rapidly bound to aerosols and thus highly subject to dry deposition. The relatively high observed values of (137)Cs in grass, soil and fresh goat and cow milk samples were probably from Chernobyl fallout and global fallout from past nuclear tests rather than from the Fukushima accident. Finally, a dose assessment for the region of investigation showed clearly that the detected activities in all environmental samples were very far below levels of concern.

Radioactive impact in South Korea from the damaged nuclear reactors in Fukushima: evidence of long and short range transport

Traces of long-lived fallout-derived radioisotopes ((134)Cs and (137)Cs) were found in wet and dry deposition samples collected from the west and east coasts of South Korea from March to May 2011 following the release of radionuclides from the damaged nuclear power plants in Fukushima, Japan. The analysis of air mass back trajectory and atmospheric pressure systems indicated that the Fukushima-derived radiocaesium had predominantly reached South Korea from the west by surface westerlies from 11 March to 5 April; however, after 6 April, air masses arrived from Japan directly due to a high pressure system that developed to the east of Japan. Spatial variation of deposition fluxes of radiocaesium in South Korea was partly attributed to the presence of local longitudinal orography.

Influence of the Fukushima Dai-ichi nuclear accident on Spanish environmental radioactivity levels

This paper presents measurements of the effect of the atmospheric radioactive release from the Fukushima Dai-ichi nuclear power station at three sites belonging to the Spanish environmental monitoring system. Measured values varied depending on the locations of the sites in Spain and their respective climatic characteristics. (134)Cs, (136)Cs, (137)Cs, (131)I, and (132)Te activity concentrations in filter samples were studied and associated levels of (131)I fallout were estimated from wet and dry deposition. Particulate aerosol activity concentrations ranges, in μBq/m(3), were 1.63-3080 ((131)I), 2.8-690 ((137)Cs), 1.3-620 ((134)Cs) and 3.6-330 ((132)Te), while the associated (131)I fallout was roughly estimated to be less than 20 Bq/m(2), Gaseous (131)I was also detected and the (131)I-gaseous/(131)I-total ratio increased at the three stations from approximately 0.75 at the end of March to 0.85-0.9 during the first few days of April. Finally, the presence of (131)I in some crucial parts of the food chain was also studied. (131)I was detected in samples from goat's and cow's milk (maximum levels of 1.11 Bq/L) and in broadleaf plants (maximum level 1.42 Bq/kg).

Radionuclides from the Fukushima accident in the air over Lithuania: measurement and modelling approaches

Analyses of (131)I, (137)Cs and (134)Cs in airborne aerosols were carried out in daily samples in Vilnius, Lithuania after the Fukushima accident during the period of March-April, 2011. The activity concentrations of (131)I and (137)Cs ranged from 12 μBq/m(3) and 1.4 μBq/m(3) to 3700 μBq/m(3) and 1040 μBq/m(3), respectively. The activity concentration of (239,240)Pu in one aerosol sample collected from 23 March to 15 April, 2011 was found to be 44.5 nBq/m(3). The two maxima found in radionuclide concentrations were related to complicated long-range air mass transport from Japan across the Pacific, the North America and the Atlantic Ocean to Central Europe as indicated by modelling. HYSPLIT backward trajectories and meteorological data were applied for interpretation of activity variations of measured radionuclides observed at the site of investigation. (7)Be and (212)Pb activity concentrations and their ratios were used as tracers of vertical transport of air masses. Fukushima data were compared with the data obtained during the Chernobyl accident and in the post Chernobyl period. The activity concentrations of (131)I and (137)Cs were found to be by 4 orders of magnitude lower as compared to the Chernobyl accident. The activity ratio of (134)Cs/(137)Cs was around 1 with small variations only. The activity ratio of (238)Pu/(239,240)Pu in the aerosol sample was 1.2, indicating a presence of the spent fuel of different origin than that of the Chernobyl accident.

Traces of fission products in southeast Spain after the Fukushima nuclear accident

Traces of (131)I, (134)Cs and (137)Cs were measured after the Fukushima nuclear accident between 23 March and 13 April 2011 in southeast Spain. The movement of the radioactive cloud toward southeast Spain was reconstructed based on the backward and forward trajectory cluster analyses. Polar maritime air masses which had originated over North America transported the radioactive plume toward the southeast Spain. Aerosols, rainwater, vegetables and cheese were analyzed to determine the radioactive risk. The highest concentrations of (131)I, (134)Cs and (137)Cs in air samples were 2.63 ± 0.12 mBq/m(3); 0.10 ± 0.03 mBq/m(3); 0.09 ± 0.02 mBq/m(3), respectively. After precipitation on April 3rd, the maximum concentrations of (131)I, (134)Cs and (137)Cs were detected in rainwater samples, 1.10 ± 0.16 mBq/L; 0.022 ± 0.003 mBq/L; 0.05 ± 0.03 mBq/L, respectively. As a consequence, (131)I was transferred to the human food chain, and found in chard and goat cheese, 0.97 ± 0.20 Bq/kg and 0.52 ± 0.08 Bq/kg, respectively. The traces of (131)I, (134)Cs and (137)Cs detected in the different samples were so low, that there is no impact on human health or the environment in Spain after the Fukushima nuclear accident.

Tracking the complete revolution of Surface Westerlies over Northern Hemisphere using radionuclides emitted from Fukushima

Massive amounts of anthropogenic radionuclides were released from the nuclear reactors located in Fukushima (northeastern Japan) between 12 and 16 March 2011 following the earthquake and tsunami. Ground level air radioactivity was monitored around the globe immediately after the Fukushima accident. This global effort provided a unique opportunity to trace the surface air mass movement at different sites in the Northern Hemisphere. Based on surface air radioactivity measurements around the globe and the air mass backward trajectory analysis of the Fukushima radioactive plume at various places in the Northern Hemisphere by employing the Hybrid Single-Particle Lagrangian Integrated Trajectory model, we show for the first time, that the uninterrupted complete revolution of the mid-latitude Surface Westerlies took place in less than 21 days, with an average zonal velocity of>60 km/h. The position and circulation time scale of Surface Westerlies are of wide interest to a large number of global researchers including meteorologists, atmospheric researchers and global climate modellers.

Soil radiocesium distribution in rice fields disturbed by farming process after the Fukushima Dai-ichi Nuclear Power Plant accident

A magnitude 9.0 earthquake and subsequent large tsunami hit the northeastern coast of Japan on March 11, 2011. This resulted in serious damage to the reactors of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), operated by the Tokyo Electric Power Company. Large amounts of radionuclides were released from the FDNPP, a proportion of which were deposited onto the ground. In this study, we investigated soil radiocesium contamination of rice fields in Aga and Minamiuonuma, Niigata, ~130 and 200 km away from the FDNPP, respectively, as Niigata is one of the largest rice growing regions in Japan. Soil samples were collected from the plow layer of five rice fields in August and September, 5-6 months after the FDNPP accident. Results showed that radiocesium concentrations (the sum of Cs-134 and Cs-137) in the rice soil samples were ~300 Bq (kg dry soil)(-1). All samples contained a Cs-134/Cs-137 activity ratio of 0.68-0.96 after correction to March 11, 2011, showing that the radiocesium released from the FDNPP were deposited on these areas. Although the rice fields had been disturbed by farming processes after the FDNPP accident, the depth distribution of radiocesium concentrations in the plow layers showed higher concentrations in the upper soil layers. This suggests that spring tillage, flooding and puddling performed before rice transplantation may not disperse radiocesium deposited on the surface through the whole plow layer. In addition, the planar distribution of radiocesium concentrations was examined near the water inlet in one of the rice fields. Highest activities were found aligned with the direction of irrigation water discharge, indicating that radioactivity levels in rice fields may be elevated by an influx of additional radionuclides, probably in irrigation water, during farming.

Depositional fluxes and residence time of atmospheric radioiodine (131I) from the Fukushima accident

Activities of radioiodine ((131)I) along with (210)Pb and (210)Po in time series precipitation samples were measured to determine the depositional fluxes of (131)I in the Southern United States and its removal rate and residence time in the atmosphere during the Fukushima nuclear accident. Radioiodine released from the Fukushima accident reached the Southern United States within 11 days, giving rise to a concurrent (131)I peak and anomalous (210)Po/(210)Pb ratios in the precipitation samples. The cumulative (131)I depositional flux was 4.6 ± 0.2 Bq m(-2) during the maximum fallout. The removal rate of (131)I out of the atmosphere, derived from a definite (131)I integral model, ranged from 0.03 to 0.14 d(-1) with an average of 0.08 ± 0.02 d(-1), which corresponds to a residence time of (131)I in the atmosphere of 12 ± 3 days, consistent with the resident timescale constrained by the (210)Po/(210)Pb disequilibrium technique. These results support our hypothesis that radioiodine was removed from the atmosphere by precipitation within two weeks. It seemed that regions reachable by (131)I transport within two weeks from Fukushima Japan would receive much more fallout, whereas places outside that distance would be relatively less polluted with radionuclides.

Radiological impact in Korea following the Fukushima nuclear accident

The pathway and radiological impact of the radioactive plume released at the Fukushima nuclear accident site on the Korean Peninsula has been studied. On March 28, 2011, only (131)I was first observed at all 12 regional monitoring stations in Korea, and the highest activity concentrations in aerosol were 3.12 mBq/m(3) for (131)I at Gunsan, 1.19 mBq/m(3) for (134)Cs and 1.25 mBq/m(3) for (137)Cs at Busan on April 7, 2011. These radionuclides were also detected in dry and wet deposition samples, while the significant increase of (131)I, (134)Cs and (137)Cs activity concentrations were not observed in seawater and marine biota samples.

Radionuclides in the ground-level atmosphere in Vilnius, Lithuania, in March 2011, detected by gamma-ray spectrometry

This study presents the ground-level air monitoring results obtained in Vilnius, the capital of Lithuania, on 14 March-14 April 2011 after the recent earthquake and subsequent Tsunami having a crucial impact on Japanese nuclear reactors at the Fukushima Daiichi Nuclear Power Plant (NPP) on 11 March 2011. To collect representative diurnal aerosol samples a powerful sampling system ensuring the air filtration rate of 5500 m(3) h(-1) was used. The following artificial gamma-ray emitting radionuclides have been determined: (129m)Te, (132)Te (in equilibrium with its daughter (132)I), (131)I, (134)Cs, (136)Cs and (137)Cs. Activity concentration of the globally distributed fission product (137)Cs has increased from a background value of 1.6 μBq m(-3) to the value of 0.9 mBq m(-3) at the beginning of April. The activity ratio (134)Cs/(137)Cs was found to be close to 1, with a slightly higher activity of (134)Cs. The maximum aerosol-associated (131)I activity concentration of 3.45 mBq m(-3) was by four orders of magnitude lower than that measured at the same location in April-May 1986 as a consequence of the Chernobyl NPP accident. The estimated gaseous fraction of iodine-131 constituted about 70% of the total (131)I activity.

Radionuclide analysis on bamboos following the Fukushima nuclear accident

In response to contamination from the recent Fukushima nuclear accident, we conducted radionuclide analysis on bamboos sampled from six sites within a 25 to 980 km radius of the Fukushima Daiichi nuclear power plant. Maximum activity concentrations of radiocesium (134)Cs and (137)Cs in samples from Fukushima city, 65 km away from the Fukushima Daiichi plant, were in excess of 71 and 79 kBq/kg, dry weight (DW), respectively. In Kashiwa city, 195 km away from the Fukushima Daiichi, the sample concentrations were in excess of 3.4 and 4.3 kBq/kg DW, respectively. In Toyohashi city, 440 km away from the Fukushima Daiichi, the concentrations were below the measurable limits of up to 4.5 Bq/kg DW. In the radiocesium contaminated samples, the radiocesium activity was higher in mature and fallen leaves than in young leaves, branches and culms.