Investigating subsurface pathways of Fukushima cesium in the Northwest Pacific

A© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cedarholm, E. R., Rypina, I. I., Macdonald, A. M., & Yoshida, S. Investigating subsurface pathways of Fukushima cesium in the Northwest Pacific. Geophysical Research Letters, 46(12), (2019): 6821-6829, doi:10.1029/2019GL082500.Advective pathways for Fukushima Daiichi Nuclear Power Plant (FDNPP)‐derived cesium observed in 2013 at 166°E south of the Kuroshio Extension (KE) at >500 m on the 26.5σθ isopycnal are investigated. Attention is paid to the KE's role in shaping these pathways. Using a high‐resolution model, particle trajectories were simulated backward and forward in time on 26.5σθ between the 2013 observations and the 2011 source. A large fraction of backtracked trajectories interacted with the mixed layer just offshore of the FDNPP. The likeliest pathway reaching the deepest 2013 observed cesium location runs along the KE out to ~165°E, where it turns sharply southward. Forward trajectory statistics suggest that for 26.5σθ waters originating north of the KE, this current acted as a permeable barrier west of 155–160°E. The deepest 2011 model mixed layers suggest that FDNPP‐derived radionuclides may have been present at 30°N in 2013 at greater depths and densities (700 m; 26.8σθ).We would like to thank our two anonymous reviewers for their insightful suggestions that improved this paper. Work by Cedarholm on this project was supported by the WHOI Summer Student Fellowship program and was her UNH senior Capstone project. Rypina, Macdonald, and Yoshida acknowledge salary and project support from the National Science Foundation (NSF) grant OCE‐1356630. Additionally, Rypina would like to acknowledge support from NSF grant OCE‐1558806. CLIVAR PO2 and P10 observations, data sets 318M20130321 and 49NZ2012011, were obtained from the CCHDO (https://cchdo.ucsd.edu/) and the HYCOM output, data set GLBa0.08 expt_90.0v, from https://www.hycom.org/. Argo profiles were obtained from http://www.argodatamgt.org, the ISAS‐15 0.5°gridded Argo‐data‐alone product from https://www.seanoe.org, and delayed‐time allsat AVISO gridded surface velocity estimates from http://marine.copernicus.eu. Extended acknowledgements in Text S4

Multi-iteration approach to studying tracer spreading using drifter data

Author Posting. © American Meteorological Society, 2017. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 47 (2017): 339-351, doi:10.1175/JPO-D-16-0165.1.A novel multi-iteration statistical method for studying tracer spreading using drifter data is introduced. The approach allows for the best use of the available drifter data by making use of a simple iterative procedure, which results in the statistically probable map showing the likelihood that a tracer released at some source location would visit different geographical regions, along with the associated arrival travel times. The technique is tested using real drifter data in the North Atlantic. Two examples are considered corresponding to sources in the western and eastern North Atlantic Ocean, that is, Massachusetts Bay–like and Irish Sea–like sources, respectively. In both examples, the method worked well in estimating the statistics of the tracer transport pathways and travel times throughout the entire North Atlantic. The role of eddies versus mean flow is quantified using the same technique, and eddies are shown to significantly broaden the spread of a tracer. The sensitivity of the results to the size of the source domain is investigated and causes for this sensitivity are discussed.This work was supported by the Grant OCE-1356630 from the National Science Foundation (NSF). Rypina also acknowledges NSF Grant OCE-1154641 and NASA Grant NNX14AH29G.2017-07-3

Observed eastward progression of the Fukushima 134Cs signal across the North Pacific

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 42 (2015): 7139–7147, doi:10.1002/2015GL065259.Radionuclide samples taken as part of hydrographic surveys at 30°N in the North Pacific reveal that the easternmost edge of Fukushima-derived 134Cs observed at 174.3°W in 2012 had progressed eastward across the basin to 160.6°W by 2013. The 2013 30°N observations indicate surface 134Cs concentrations of 3–5 Bq/m3 between 160°E and 160°W, slightly lower concentrations west of 160°E and no detectable signal east of 160.6°W. Profile samples show 134Cs penetration to 500 m west of 180° with shoaling penetration depth toward to the east. The near-uniform vertical distribution of 137Cs between 152°W and 121.3°W in the top 500 m is indicative of trace amounts of radionuclides remaining from weapons testing. The physical processes responsible for the deep 134Cs penetration in the western Pacific appear to be related to distinct water mass subduction pathways; however, the timing and rapidity of deep penetration over the broad scales observed has yet to be clarified.National Science Foundation Grant Number: OCE-1356630, Gordon and Betty Moore Foundation Grant Number: GBMF3007, Deerbrook Charitable Trust Grant Number: WHOI-DCT#12-122016-03-0

Drifter-based estimate of the 5 year dispersal of Fukushima-derived radionuclides

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8177–8193, doi:10.1002/2014JC010306.Employing some 40 years of North Pacific drifter-track observations from the Global Drifter Program database, statistics defining the horizontal spread of radionuclides from Fukushima nuclear power plant into the Pacific Ocean are investigated over a time scale of 5 years. A novel two-iteration method is employed to make the best use of the available drifter data. Drifter-based predictions of the temporal progression of the leading edge of the radionuclide distribution are compared to observed radionuclide concentrations from research surveys occupied in 2012 and 2013. Good agreement between the drifter-based predictions and the observations is found.This work was supported by the grant OCE-1356630 from the National Science Foundation. Data for cesium isotopes was supported by grants from the Gordon and Betty Moore Foundation (grant GBMF3007) and the Deerbrook Charitable Trust

教材としてのマンガ

"本稿は,マンガを用いた教育について,この20 年の研究を概観したものである.はじめに,マンガのわかりやすさについて述べ,教材としてのマンガについて,その有用性を,「マンガを読む」「マンガを描く」に大別して紹介した.最後に,知識を得るという目的以外のマンガ利用についても簡単にふれた.教材としてのマンガの可能性は大きいといえよう.

Tributyltin Inhibits Neural Induction of Human Induced Pluripotent Stem Cells

Tributyltin (TBT), one of the organotin compounds, is a well-known environmental pollutant. In our recent study, we reported that TBT induces mitochondrial dysfunction, in human-induced pluripotent stem cells (iPSCs) through the degradation of mitofusin1 (Mfn1), which is a mitochondrial fusion factor. However, the effect of TBT toxicity on the developmental process of iPSCs was not clear. The present study examined the effect of TBT on the differentiation of iPSCs into the ectodermal, mesodermal, and endodermal germ layers. We found that exposure to nanomolar concentration of TBT (50 nM) selectively inhibited the induction of iPSCs into the ectoderm, which is the first step in neurogenesis. We further assessed the effect of TBT on neural differentiation and found that it reduced the expression of several neural differentiation marker genes, which were also downregulated by Mfn1 knockdown in iPSCs. Taken together, these results indicate that TBT induces developmental neurotoxicity via Mfn1-mediated mitochondrial dysfunction in iPSCs

エホンヲカイシタオヤコノコミュニケーションノハッタツ

"絵本の読み聞かせ場面における親子のやりとりを長期にわたり追跡し,横断的・縦断的に検討したものを概括した.追跡調査は継続中であるが,0歳から4歳までの経過からは,各親子で独自の読み聞かせスタイルがあること,そのスタイルは,こどもが発達しても大きくは変わらないことが示された

Desensitization of delayed-type hypersensitivity in mice: suppressive environment

The systemic injection of high doses of antigen into a preimmunized animal results in transient unresponsiveness of cell-mediated immune responses. This phenomenon is known as desensitization. Serum interleukin 2 (IL-2) activity was found transiently in desensitized mice at 3 h after the antigen challenge. These mice could not reveal antigen nonspecific delayed-type hypersensitivity (DTH) 1 d after the challenge. Specific suppression of DTH was observed at later stages. Sera from 3 h desensitized mice showed suppressive effects on DTH in preo immunized mice. Administration of recombinant IL-2 into preimmunized mice led to the failure of development of DTH to antigens. These observations suggest that IL-2 plays an important role in the suppressive environment

Short-term dispersal of Fukushima-derived radionuclides off Japan : modeling efforts and model-data intercomparison

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 4973-4990, doi:10.5194/bg-10-4973-2013.The Great East Japan Earthquake and tsunami that caused a loss of power at the Fukushima nuclear power plants (FNPP) resulted in emission of radioactive isotopes into the atmosphere and the ocean. In June of 2011, an international survey measuring a variety of radionuclide isotopes, including 137Cs, was conducted in surface and subsurface waters off Japan. This paper presents the results of numerical simulations specifically aimed at interpreting these observations and investigating the spread of Fukushima-derived radionuclides off the coast of Japan and into the greater Pacific Ocean. Together, the simulations and observations allow us to study the dominant mechanisms governing this process, and to estimate the total amount of radionuclides in discharged coolant waters and atmospheric airborne radionuclide fallout. The numerical simulations are based on two different ocean circulation models, one inferred from AVISO altimetry and NCEP/NCAR reanalysis wind stress, and the second generated numerically by the NCOM model. Our simulations determine that > 95% of 137Cs remaining in the water within ~600 km of Fukushima, Japan in mid-June 2011 was due to the direct oceanic discharge. The estimated strength of the oceanic source is 16.2 ± 1.6 PBq, based on minimizing the model-data mismatch. We cannot make an accurate estimate for the atmospheric source strength since most of the fallout cesium had left the survey area by mid-June. The model explained several key features of the observed 137Cs distribution. First, the absence of 137Cs at the southernmost stations is attributed to the Kuroshio Current acting as a transport barrier against the southward progression of 137Cs. Second, the largest 137Cs concentrations were associated with a semi-permanent eddy that entrained 137Cs-rich waters, collecting and stirring them around the eddy perimeter. Finally, the intermediate 137Cs concentrations at the westernmost stations are attributed to younger, and therefore less Cs-rich, coolant waters that continued to leak from the reactor in June of that year.Irina Rypina was partially supported by Grant NSF-OCE-0725796. This work is funded by the Gordon and Betty Moore Foundation through Grant GBMF3007 to Ken Buesseler