Variation of Cs activity concentration in flood and pore water in paddy fields and its transfer to rice.

Caesium-137 (Cs) is a major anthropogenic radionuclide released into the environment as a result of the TEPCO Fukushima Daiichi Nuclear Reactor Station accident (occurring on March 11, 2011). Rice, being a staple food in Asian countries, including Japan, and is predominantly cultivated in paddy fields. Consequently, Cs present in rice is absorbed from both soil and irrigation water, making it the most important crop for estimating internal radiation doses.

Chemical implication of the partition coefficient of Cs between the suspended and dissolved phases in natural water.

After the Fukushima Daiichi nuclear power plant accident, the terrestrial environment became severely contaminated with radiocesium. Consequently, the river and lake water in the Fukushima area exhibited high radiocesium levels, which declined subsequently. The partition coefficient of Cs between the suspended sediment (SS) and dissolved phases, K, was introduced to better understand the dynamic behavior of Cs in different systems.

Transfer of Cs and Sr from soil-to-potato: Interpretation of the association from global fallout in Aomori to accidental release in Fukushima and Chornobyl.

Ceasium-137 and Sr are major artificial radionuclides that have been released into the environment. Soil-to-plant transfer of radionuclides is an important route to food contamination. The radionuclide activity concentrations in crops must be quantitatively predicted for estimating the internal radiation doses from food ingestion.

Rapid survey of de novo mutations in naturally growing tree species following the March 2011 disaster in Fukushima: The effect of low-dose-rate radiation.

The impact of low-dose-rate radiation on genetics is largely unknown, particularly in natural environments. The Fukushima Dai-ich Nuclear Power Plant disaster resulted in the creation of contaminated natural lands. In this study, de novo mutations (DNMs) in germ line cells were surveyed from double-digest RADseq fragments in Japanese cedar and flowering cherry trees exposed to ambient dose rates ranging from 0.

SOIL-SOIL SOLUTION DISTRIBUTION COEFFICIENT OF RADIOIODINE IN SURFACE SOILS AROUND SPENT NUCLEAR FUEL REPROCESSING PLANT IN ROKKASHO, JAPAN.

The soil-soil solution distribution coefficient (Kd) of radioiodine in soil samples with various total carbon (TC) contents was measured in a batch sorption experiment using 125I tracer spiked as I-. The log values of Kd-125I and TC concentration in low-TC soils (< 10g kg-1) were positively correlated, whereas those of Kd-125I in TC rich soils (> 10 g kg-1) and dissolved organic carbon (DOC) in liquid phase were negatively correlated. The proportion of 125I in the < 3 kDa fraction in the liquid phase is negatively correlated with the log of DOC, implying that 125I is primarily combined with high-molecular-weight organic matter in soil solutions rich in DOC.

Estimation of rooting depth of Cs uptake by plants.

Understanding the soil-to-plant transfer process of Cs is essential for predicting the contamination levels of plants in contaminated areas. The rooting depth is considered one of the key factors explaining the difference in the activity concentration of Cs in different plant species. In this study, the distributions of Cs and Cs in soils and plants were investigated, and the plants' rooting depth of Cs uptake was estimated using the Cs/Cs ratios in exchangeable fractions of soils and biological samples.

Accumulation of Cs in aggregated organomineral assemblage in pasture soils 8 years after the accident at the Fukushima Daiichi nuclear power plant.

Despite the presence of minerals that allow Cs fixation in soils, Cs remains available to crops for several years after its deposition, particularly in pasture soils. Larger amounts of organic matter derived from herbage residues are accumulated in pasture soils than in tilled farmland soils. As the above-ground part of herbage crops initially received airborne Cs during the accident at Fukushima Daiich nuclear power plant (FDNPP), the organic matter originated from the contaminated herbage should play an important role in the fate of Cs in soils.

Radiation dose rate to Japanese cedar and plants collected from Okuma, Fukushima Prefecture.

After the 2011 Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident, wild populations of animals and plants living in the evacuation zone received additional ionizing radiation of both internal and external radiation doses. Morphological abnormalities of pine and fir trees near the FDNPS were reported. In order to evaluate dose-effect relationships, it is necessary to quantify the radiation doses to trees and plants.

Differentiating Fukushima and Nagasaki plutonium from global fallout using Pu/Pu atom ratios: Pu vs. Cs uptake and dose to biota.

Plutonium (Pu) has been released in Japan by two very different types of nuclear events - the 2011 Fukushima accident and the 1945 detonation of a Pu-core weapon at Nagasaki. Here we report on the use of Accelerator Mass Spectrometry (AMS) methods to distinguish the FDNPP-accident and Nagasaki-detonation Pu from worldwide fallout in soils and biota. The FDNPP-Pu was distinct in local environmental samples through the use of highly sensitive Pu/Pu atom ratios.

Relationship between radiocaesium in muscle and physicochemical fractions of radiocaesium in the stomach of wild boar.

After the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 2011, it became important to study radiation dynamics, assess internal radiation exposure and specify factors affecting radionuclide variation in wildlife. Therefore, it is necessary to investigate which physicochemical fractions of radiocaesium (Cs) are absorbed from ingested material in species with high activity concentrations of Cs, such as wild boar. This study analysed the physicochemical fractions of Cs in the stomach contents of wild boar to evaluate the transfer from ingested food to muscle.

Effects of organic amendments on the natural attenuation of radiocesium transferability in grassland soils with high potassium fertility.

Organic amendments affect the behavior of radiocesium in soil-plant systems in a complex way; they can inhibit radiocesium fixation by clay minerals by blocking selective sorption sites, whereas K supplied to the soil solution by amendments can reduce Cs uptake by plant roots. Here, we investigated the influence of inorganic and organic amendments on the transferability of radiocesium from soil to grass seedling in a humus-rich Andosol with high exchangeable K content. Soil samples were spiked with aCs tracer, treated with N, N-P-K, compost (cattle manure using rice straw), or no amendment (control soil), and subjected to repeated two-week wetting and air-drying treatments for one year in an artificial climate chamber.

Dynamics of Strontium and geochemically correlated elements in soil during washing remediation with eco-complaint chelators.

In the study, the dynamics of Sr and geochemically correlated elements (Ca, Ba, and Y) in soil with chelators in the mix (soil to chelator ratio, 1:10; matrix, HO) were assessed to understand chemical-induced washing remediation of radiogenic waste solids. Specifically, EDTA (2,2',2″,2‴-(ethane-1,2-diyldinitrilo)tetraacetic acid), EDDS (2-[2-(1,2-dicarboxyethylamino)ethylamino]butanedioic acid), GLDA (2-[bis(carboxymethyl)amino]pentanedioic acid), and HIDS (2-(1,2-dicarboxyethylamino)-3-hydroxy-butanedioic acid) are chelators that are used as extractants. The effect of solution pH on chelator-induced extractions of the target elements (t-Es: Sr, Ca, Ba, or Y) from soil and stability constants of the t-Es complexes with chelators were used to explain the trends and magnitudes in interactions.

Vertical distribution of I and radiocesium in forest soil collected near the Fukushima Daiichi Nuclear Power Plant boundary.

Three soil core samples were collected from a forest located about 1.1 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) boundary in 2017, and the vertical profiles of I from the FDNPP accident were determined by the combination of TMAH (tetramethyl ammonium hydroxide) extraction and ICP-MS/MS analysis. The humus layer above the soil layer was heavily contaminated with Cs (1983-5985 Bq g) and Cs (1947-5902 Bq g) (decay-corrected to March 11, 2011).

Phytoavailability of Cs and stable Cs in soils from different parent materials in Fukushima, Japan.

Weathered micaceous minerals (micas) are able to release potassium ion (K) and fix caesium-137 (Cs), both of which reduce soil-to-plant transfer of Cs. Among micas, trioctahedral micas such as biotite is expected to have a stronger ability to supply nonexchangeable K and a higher amount of Cs fixation sites than dioctahedral micas such as illite. Although biotite is predominant in granitic soils (G soils), illite is mainly dominant in sedimentary rock soils (S soils).

The transfer of fallout plutonium from paddy soil to rice: A field study in Japan.

Reported transfer factor (TF) values of Pu from paddy soil to rice are rather scarce, despite the radiotoxicity of Pu and the irreplaceable role of rice in Asian peoples' diets. Here, we conducted a field study to investigate the transfer of global fallout Pu from paddy soil to rice grain (hulled rice) in Japan. The Pu/Pu atomic ratios in two rice grain samples out of 16 samples were determined and the ratios corresponded well with the global fallout value.

Changes in the Soil to Brown Rice Concentration Ratio of Radiocaesium before and after the Fukushima Daiichi Nuclear Power Plant Accident in 2011.

Radiocaesium (Cs) mobility in soil is initially relatively high when the nuclide first comes into contact with soil, after which the mobile fraction decreases with time due to Cs fixation to soil particles (aging effect). Consequently, the Cs activity concentration in plants grown in soil was expected to decrease with time after the Fukushima Daiichi nuclear power plant accident in 2011. In this study, we collated data on concentration ratios (CR) of Cs between brown rice grain and paddy soil and compared CR values reported for periods before and after the accident.

Source analysis of radiocesium in river waters using road dust tracers.

Following the Fukushima Dai-ichi Nuclear Power Station accident, regional road dust, heavily contaminated with radiocesium, now represents a potential source of radiocesium pollution in river water. To promote effective countermeasures for reducing the risk from radiocesium pollution, it is important to understand its sources. This study evaluated the utility of metals, including Al, Fe, and Zn as road dust tracers, and applied them to analyze sources of Cs in rivers around Fukushima during wet weather.

The Cs activity concentration of suspended and dissolved fractions in irrigation waters collected from the 80 km zone around TEPCO's Fukushima Daiichi Nuclear Power Station.

Fifty-four samples of irrigation water were collected in 2014 from agricultural ponds, rivers, and dams within the 80 km zone around TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS). The samples were filtered with a 0.45 μm pore-size membrane filter to produce suspended and dissolved fractions.

Soil-soil solution distribution coefficient of soil organic matter is a key factor for that of radioiodide in surface and subsurface soils.

We investigated the vertical distribution of the soil-soil-solution distribution coefficients (K) of I, Cs, and Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. K of Cs was highly correlated with water-extractable K. K of Sr was highly correlated with water-extractable Ca and SOC.

Concentration of radiocaesium in rice and irrigation water, and soil management practices in Oguni, Date, Fukushima.

The concentration of radiocaesium ((134) Cs and (137) Cs) in brown rice collected from Oguni, Date, Fukushima in 2011 was over 500 Bq kg(-1) , which was the provisional regulation value in 2011, and rice cultivation was prohibited in 2012. Rice culture was resumed following the application of K fertilizer as a countermeasure in 2013. The concentration of (137) Cs in soils and irrigation water in 2013 was in the range of 1200 to 4000 Bq kg(-1) (n = 31) and 0.

Determination of Iodide, Iodate and Total Iodine in Natural Water Samples by HPLC with Amperometric and Spectrophotometric Detection, and Off-line UV Irradiation.

We developed a rapid, simple method for the iodine speciation analysis of water and applied it to natural water samples. Simultaneous determinations of I(-) and IO3(-) were achieved with an HPLC system with amperometric detection for I(-) and spectrophotometric detection after a postcolumn reaction for IO3(-). We determined the I(-) and IO3(-) concentrations in 20-μL water samples within 10 min.

Regression model analysis of the decreasing trend of cesium-137 concentration in the atmosphere since the Fukushima accident.

The decreasing trend of the atmospheric Cs concentration in two cities in Fukushima prefecture was analyzed by a regression model to clarify the relation between the parameter of the decrease in the model and the trend and to compare the trend with that after the Chernobyl accident. The Cs particle concentration measurements were conducted in urban Fukushima and rural Date sites from September 2012 to June 2015. The Cs particle concentrations were separated in two groups: particles of more than 1.

Simultaneous determination of radiocesium ((135)Cs, (137)Cs) and plutonium ((239)Pu, (240)Pu) isotopes in river suspended particles by ICP-MS/MS and SF-ICP-MS.

Due to radioisotope releases in the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, long-term monitoring of radiocesium ((135)Cs and (137)Cs) and Pu isotopes ((239)Pu and (240)Pu) in river suspended particles is necessary to study the transport and fate of these long-lived radioisotopes in the land-ocean system. However, it is expensive and technically difficult to collect samples of suspended particles from river and ocean. Thus, simultaneous determination of multi-radionuclides remains as a challenging topic.

Addressing ecological effects of radiation on populations and ecosystems to improve protection of the environment against radiation: Agreed statements from a Consensus Symposium.

This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters' accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks.