Atmospheric resuspension of insoluble radioactive cesium-bearing particles found in the difficult-to-return area in Fukushima

The deposition of insoluble radiocesium-bearing microparticles (CsMPs), which were released from the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident in March 2011, has resulted in the widespread contamination of eastern Japan. Obviously, these deposited insoluble CsMPs may become the secondary contamination sources by atmospheric migration or other environmental transferring process; however, the understanding of the transport mechanism remains non-elucidation, and the relevant evidence has not been directly provided. This study, for the first time, provides the direct evidence for the resuspension of these insoluble CsMPs to the atmosphere from (1) proximity of ¹³⁷Cs radioactivity and resemblance of the morphology and the elemental compositions of CsMPs in the samples of soil and aerosol derived from the same sampling site, (2) the special characteristics of the resuspended CsMPs of which the ratios of Na/Si, K/Si and/or Cs/Si were smaller than those from the initially released CsMPs collected at either long distance or near F1NPP, which can be ascribed to the slowly natural corrosion of CsMPs by the loss of the small amount of soluble contents in CsMPs, and (3) high CsMPs concentration of 10 granules/g in the surface soil of our sampling site and high resuspension frequency of CsMPs in spring when predominant suspended particles were soil dust. Specifically, 15 single CsMPs were successfully isolated from the aerosol filters collected by unmanned high-volume air samplers at a severely polluted area in Fukushima Prefecture, about 25 km away from F1NPP, from January 2015 to September 2019. The mean diameter of these CsMPs was 1.8 ± 0.5 μm, and the average ¹³⁷Cs radioactivity was 0.35 ± 0.23 Bq/granule. The contribution rate of the resuspended CsMPs to the atmospheric radiocesium was estimated from the ratio of ¹³⁷Cs radioactivity of a single CsMP to that of the aerosol filter to be of 23.9 ± 15.3%. There has been no considerable decreasing trend in the annual CsMP resuspension frequency

Rain-induced bioecological resuspension of radiocaesium in a polluted forest in Japan

放射性セシウムを含む真菌類の大型胞子の放出が森林環境での雨により増加することを発見 --降水によるバイオエアロゾル大気放出の新証拠--. 京都大学プレスリリース. 2020-10-01.It is the conventional understanding that rain removes aerosols from the atmosphere. However, the question of whether rain plays a role in releasing aerosols to the atmosphere has recently been posed by several researchers. In the present study, we show additional evidence for rain-induced aerosol emissions in a forest environment: the occurrence of radiocaesium-bearing aerosols in a Japanese forest due to rain. We carried out general radioactive aerosol observations in a typical mountainous village area within the exclusion zone in Fukushima Prefecture to determine the impacts and major drivers of the resuspension of radiocaesium originating from the nuclear accident in March 2011. We also conducted sampling according to the weather (with and without rain conditions) in a forest to clarify the sources of atmospheric radiocaesium in the polluted forest. We found that rain induces an increase in radiocaesium in the air in forests. With further investigations, we confirmed that the fungal spore sources of resuspended radiocaesium seemed to differ between rainy weather and nonrainy weather. Larger fungal particles (possibly macroconidia) are emitted during rainy conditions than during nonrainy weather, suggesting that splash generation by rain droplets is the major mechanism of the suspension of radiocaesium-bearing mould-like fungi. The present findings indicate that radiocaesium could be used as a tracer in such research fields as forest ecology, meteorology, climatology, public health and agriculture, in which fungal spores have significance

Impacts on air dose rates after the Fukushima accident over the North Pacific from 19 March 2011 to 2 September 2015

A fleet of thirteen in-service global container ships continuously measured the air dose rates over the North Pacific after the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The results showed that the elevated air dose rates over the Port of Tokyo and the FDNPS emissions are significantly correlated (log(emission fluxes) = 54.98 x (air dose rates) (R = 0.95, P-value<0.01), and they are also significantly correlated with the Tsukuba deposition fluxes (log(deposition fluxes) = 0.47 + 30.98 (air dose rates) (R = 0.91, P-value<0.01). These results demonstrate the direct impact of the FDNPS emissions on the depositions of radionuclides and the air dose rates over the Port of Tokyo. Over the North Pacific, the correlation equations are log(emission fluxes) = -2.72 + 202.36 x (air dose rates over the northwestern Pacific) (R = 0.40, P-value<0.01), and log(emission fluxes) = -0.55 + 80.19 x (air dose rates over the northeastern Pacific) (R = 0.29, P-value = 0.0424). These results indicate that the resuspension of the deposited radionuclides have become a dominant source in the transport of radionuclides across the North Pacific. Model simulations show underestimated air dose rates during the periods of 22-25 March 2011 and 27-30 March 2011 indicating the lack of mechanisms, such as the resuspension of radionuclides, in the model

The seasonal variations of atmospheric 134,137Cs activity and possible host particles for their resuspension in the contaminated areas of Tsushima and Yamakiya, Fukushima, Japan

A large quantity of radionuclides was released by the Fukushima Daiichi Nuclear Power Plant accident in March 2011, and those deposited on ground and vegetation could return to the atmosphere through resuspension processes. Although the resuspension has been proposed to occur with wind blow, biomass burning, ecosystem activities, etc., the dominant process in contaminated areas of Fukushima is not fully understood. We have examined the resuspension process of radiocesium (134,137Cs) based on long-term measurements of the atmospheric concentration of radiocesium activity (the radiocesium concentration) at four sites in the contaminated areas of Fukushima as well as the aerosol characteristic observations by scanning electron microscopy (SEM) and the measurement of the biomass burning tracer, levoglucosan.The radiocesium concentrations at all sites showed a similar seasonal variation: low from winter to early spring and high from late spring to early autumn. In late spring, they showed positive peaks that coincided with the wind speed peaks. However, in summer and autumn, they were correlated positively with atmospheric temperature but negatively with wind speed. These results differed from previous studies based on data at urban sites. The difference of radiocesium concentrations at two sites, which are located within a 1 km range but have different degrees of surface contamination, was large from winter to late spring and small in summer and autumn, indicating that resuspension occurs locally and/or that atmospheric radiocesium was not well mixed in winter/spring, and it was opposite in summer/autumn. These results suggest that the resuspension processes and the host particles of the radiocesium resuspension changed seasonally. The SEM analyses showed that the dominant coarse particles in summer and autumn were organic ones, such as pollen, spores, and microorganisms. Biological activities in forest ecosystems can contribute considerably to the radiocesium resuspension in these seasons. During winter and spring, soil, mineral, and vegetation debris were predominant coarse particles in the atmosphere, and the radiocesium resuspension in these seasons can be attributed to the wind blow of these particles. Any proofs that biomass burning had a significant impact on atmospheric radiocesium were not found in the present study

Investigation of the Chemical Characteristics of Individual Radioactive Microparticles Emitted from Reactor 1 by the Fukushima Daiichi Nuclear Power Plant Accident by Using Multiple Synchrotron Radiation X-ray Analyses

Seven radioactive particles were separated from a soil sample collected at the Northwest region of the Fukushima Daiichi Nuclear Power Plant (FDNPP). It has been pointed out that the soil is contaminated by radioactive materials emitted from reactor 1 of the FDNPP by the accident that occurred in March, 2011. The physical characteristics of these radioactive particles with –100 μm in diameter and non-uniform shape are clearly different from those of spherical microparticles, known as Cesium-balls, thought to be emitted from the FDNPP reactor 2. Three kinds of synchrotron radiation-based X-ray analyses (X-ray fluorescence analysis, X-ray absorption near edge structure analysis and X-ray diffraction analysis) were nondestructively applied to radioactive particles using a micro-focused X-ray beam at the SPring-8 to investigate their detailed chemical properties. Various elements related to fission products of nuclear fuel and components of the reactor were detected from the particles emitted from the FDNPP reactor 1 with an obvious heterogeneous elemental distribution. In particular, the chemical compositional feature of these particles was characterized by several elements (Sr, Ba etc.), which were easily volatilized in a reducing atmosphere. Although a main component of the particles was identified as silicate glass similar to the Cesium-balls, some crystalline materials were also found in microscopic regions containing Fe and other metallic elements. We concluded that these radioactive particles were emitted from reactor 1 to the atmosphere during 12th to 13th March, 2011. Our results suggest the fact that the nuclear fuel and the reactor vessels around the fuel were melted together at a very early stage of the accident. In addition, it was demonstrated that chemical compositional information of individual radioactive materials can be a new indicator as an alternative to the radioactive ratio to estimate the source of emissions

Anti-NXP2 autoantibodies in adult patients with idiopathic inflammatory myopathies: Possible association with malignancy

Objectives: Myositis-specific autoantibodies (MSAs) are useful tools for identifying clinically homogeneous subsets and predicting prognosis of patients with idiopathic inflammatory myopathies (IIM) including polymyositis (PM) and dermatomyositis (DM). Recent studies have shown that anti-NXP2 antibody (Ab) is a major MSA in juvenile dermatomyositis (JDM). In this study the frequencies and clinical associations of anti-NXP2 Ab were evaluated in adult patients with IIM. Methods: Clinical data and serum samples were collected from 507 adult Japanese patients with IIM (445 with DM and 62 with PM). Eleven patients with JDM, 108 with systemic lupus erythematosus, 433 with systemic sclerosis and 124 with idiopathic pulmonary fibrosis were assessed as disease controls. Serum was examined for anti-NXP2 Ab by immunoprecipitation and western blotting using polyclonal anti-NXP2 Ab. Results: Seven patients (1.6%) with adult DM and one (1.6%) with adult PM were positive for anti-NXP2 Ab. Except for two patients with JDM, none of the disease controls were positive for this autoantibody. Among eight adult patients with IIM, three had internal malignancies within 3 years of diagnosis of IIM. Another patient with DM also had a metastatic cancer at the diagnosis. All of the carcinomas were at an advanced stage (stage IIIb-IV). Conclusions: While less common than in juvenile IIM, anti-NXP2 Ab was found in adult IIM. Anti-NXP2 Ab may be associated with adult IIM with malignancy

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target