Esr and radiocarbon dating of gut strings from early plucked instruments

Early European plucked instruments have recently experienced a great revival, but a few aspects remain unknown (e.g., the gauge of gut strings). Here we report, for the first time, that the electron spin resonance (ESR) signal intensity of oxidized iron, Fe(III), from gut strings at g = 2 increases linearly with age within a few hundred years. The signal increase in the remaining old strings on early instruments can be used to judge if they are as old as or younger than the instrument. Obtaining the authenticity information of gut strings contributes to the revival of the old instruments and the music. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Application of compound-specific 14C dating to IODP Exp.318 U1357A core

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月27日（火） 国立国語研究所 ２階講

Rapid Holocene retreat of Ross Ice Shelf recorded in sedimentary 10Be and fatty acid radiocarbon

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月27日（火） 国立国語研究所 ２階講

Nutritional sources of meio- and macrofauna at hydrothermal vents and adjacent areas: Natural-abundance radiocarbon and stable isotope analyses

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nomaki, H., Uejima, Y., Ogawa, N. O., Yamane, M., Watanabe, H. K., Senokuchi, R., Bernhard, J. M., Kitahashi, T., Miyairi, Y., Yokoyama, Y., Ohkouchi, N., & Shimanaga, M. Nutritional sources of meio- and macrofauna at hydrothermal vents and adjacent areas: Natural-abundance radiocarbon and stable isotope analyses. Marine Ecology Progress Series, 622, (2019): 49-65, doi:10.3354/meps13053.Deep-sea hydrothermal vents host unique marine ecosystems that rely on organic matter produced by chemoautotrophic microbes together with phytodetritus. Although meiofauna can be abundant at such vents, the small size of meiofauna limits studies on nutritional sources. Here we investigated dietary sources of meio- and macrofauna at hydrothermal vent fields in the western North Pacific using stable carbon and nitrogen isotope ratios (δ13C, δ15N) and natural-abundance radiocarbon (Δ14C). Bacterial mats and Paralvinella spp. (polychaetes) collected from hydrothermal vent chimneys were enriched in 13C (up to -10‰) and depleted in 14C (-700 to -580‰). The δ13C and Δ14C values of dirivultid copepods, endemic to hydrothermal vent chimneys, were -11‰ and -661‰, respectively, and were similar to the values in the bacterial mats and Paralvinella spp. but distinct from those of nearby non-vent sediments (δ13C: ~-24‰) and water-column plankton (Δ14C: ~40‰). In contrast, δ13C values of nematodes from vent chimneys were similar to those of non-vent sites (ca. -25‰). Results suggest that dirivultids relied on vent chimney bacterial mats as their nutritional source, whereas vent nematodes did not obtain significant nutrient amounts from the chemolithoautotrophic microbes. The Δ14C values of Neoverruca intermedia (vent barnacle) suggest they gain nutrition from chemoautotrophic microbes, but the source of inorganic carbon was diluted with bottom water much more than those of the Paralvinella habitat, reflecting Neoverruca’s more distant distribution from active venting. The combination of stable and radioisotope analyses on hydrothermal vent organisms provides valuable information on their nutritional sources and, hence, their adaptive ecology to chemosynthesis-based ecosystems.We are grateful to the crews and scientists of the R/V ‘Natsushima’ and the ROV ‘Hyper-Dolphin’ of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) during the NT12-10, NT13-09 and NT14-06 cruises, and the R/V ‘Kaimei’ and the KM-ROV of JAMSTEC during the KM-ROV training cruise. We thank Yuki Iwadate for her help on sample preparations and 2 anonymous reviewers and the editor, who provided helpful comments on an earlier version of this manuscript. This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Scientific Research C 26440246 to M.S.), the Japan Society for the Promotion of Science (Invitational fellowships for research in Japan, S14032 to J.M.B.), the WHOI Robert W. Morse Chair for Excellence in Oceanography, and The Investment in Science Fund at WHOI

Rapid glaciation and a two-step sea-level plunge into The Last Glacial Maximum

The approximately 10,000-year-long Last Glacial Maximum, before the termination of the last ice age, was the coldest period in Earth’s recent climate history1. Relative to the Holocene epoch, atmospheric carbon dioxide was about 100 parts per million lower and tropical sea surface temperatures were about 3 to 5 degrees Celsius lower2,3. The Last Glacial Maximum began when global mean sea level (GMSL) abruptly dropped by about 40 metres around 31,000 years ago4 and was followed by about 10,000 years of rapid deglaciation into the Holocene1. The masses of the melting polar ice sheets and the change in ocean volume, and hence in GMSL, are primary constraints for climate models constructed to describe the transition between the Last Glacial Maximum and the Holocene, and future changes; but the rate, timing and magnitude of this transition remain uncertain. Here we show that sea level at the shelf edge of the Great Barrier Reef dropped by around 20 metres between 21,900 and 20,500 years ago, to −118 metres relative to the modern level. Our findings are based on recovered and radiometrically dated fossil corals and coralline algae assemblages, and represent relative sea level at the Great Barrier Reef, rather than GMSL. Subsequently, relative sea level rose at a rate of about 3.5 millimetres per year for around 4,000 years. The rise is consistent with the warming previously observed at 19,000 years ago1,5, but we now show that it occurred just after the 20-metre drop in relative sea level and the related increase in global ice volumes. The detailed structure of our record is robust because the Great Barrier Reef is remote from former ice sheets and tectonic activity. Relative sea level can be influenced by Earth’s response to regional changes in ice and water loadings and may differ greatly from GMSL. Consequently, we used glacio-isostatic models to derive GMSL, and find that the Last Glacial Maximum culminated 20,500 years ago in a GMSL low of about −125 to −130 metres.Financial support of this research was provided by the JSPS KAKENHI (grant numbers JP26247085, JP15KK0151, JP16H06309 and JP17H01168), the Australian Research Council (grant number DP1094001), ANZIC, NERC grant NE/H014136/1 and Institut Polytechnique de Bordeaux

Spatial Extent of Mid‐To Late‐Holocene Sedimentary Record of Tsunamis Along the Southern Kuril Trench, Hokkaido, Japan

Abstract With their complex cycles and rupture modes, infrequent megathrust earthquakes require a high‐resolution spatiotemporal record of tsunami inundations over thousands of years to provide more accurate long‐term forecasts. The geological record suggests that Mw > 8 earthquakes in the Kuril Trench occurred at intervals of several hundred years. However, uncertainties remain regarding the rupture zone, owing to the limited survey areas and chronological data. Therefore, we investigated the tsunami deposits in a coastal wetland of southeastern Hokkaido, Japan, to characterize the tsunamis that originated from the Kuril Trench over the last 4,000 years. On the Erimo coast, more than seven sand layers exhibited common features of tsunami deposits, such as sheet distributions of several hundred meters, normal grading structures, and sharp basal contacts. According to numerical tsunami simulations, the 17th‐century sand layer could be reproduced using a multiple rupture zone model (Mw ∼ 8.8). We used high‐resolution radiocarbon dating and tephras to correlate the tsunami deposits from the last 4,000 years with those reported from regions ∼100 km away. The tsunami history revealed here shows good agreement with the histories of adjacent regions. However, the paleotsunamis reported to have occurred in regions >200 km away include events that differ from those in this study, suggesting a diversity of Mw > 8 earthquakes in the Kuril Trench. We clarified the history and extents of earthquake‐generated tsunamis along the southwestern end of the Kuril Trench, which were previously unknown. Our results provide a framework for magnitude estimations and long‐term forecasts of earthquakes

Relationship between depositional environments and preservabilities of Holocene tsunami deposits on the Hidaka coast, Hokkaido, Japan

Rising sea levels and associated coastal topography changes are expected to increase coastal vulnerability to tsunamis. Reliable records of the periodicity of the most damaging tsunamis, with recurrence intervals of several centuries, are often incomplete. To understand the likelihood of coastal disasters that would be worsened by sea-level rise, as well as their possible occurrence leading to the actual extent of inland inundation, it is useful to examine the geological record of the mid-Holocene highstand periods to supplement the written archives. However, the formation and preservation potential of event layers depends heavily on the depositional environment resulting from coastal evolutions. This study attempted to reconstruct the depositional environment changes using diatom and chemical analyses on the Hidaka coast of Hokkaido, Japan, to examine the preservation of event layer archives.Following field investigations, we found three sand layers formed by extreme waves from field investigations. The relationship between the depositional environment and the timing of the event layer formation over the past 7000 years along the central Hidaka coast indicates that supratidal to freshwater marsh environments are the most suitable for preserving tsunami deposits in this region. Since sand layers in the distant areas from wave sources were not well preserved in upland (as at elevations above marsh environment) and saltmarsh environments, the time windows of preservation were very limited depending on the depositional environments with relative sea-level changes. On the other hand, in areas closer to the Kuril Trench, sand layers were preserved not very sensitive to the depositional environment, suggesting that the event archive length is related to the magnitude of tsunamis

The use of radiocarbon to evaluate the trophic role of geothermal bacteria in shallow hydrothermal water ecosystem

Stable isotopes such as δ13C and δ15N are routinely used in trophic ecology as isotope values are derived from diet and recorded subsequent fractionation in consumer tissue. However, this approach necessitates to estimate a priori the fractionation between food source and consumer leading to potential uncertainties. In this context, the development of additional biomarkers enables to have better resolution on feeding habits. Dissolved Inorganic Carbon (DIC) from volcanic activity and bacteria using this DIC presents a strongly depleted natural radiocarbon abundances (Δ14C). Through its activity, the geothermal plant of Bouillante in Guadeloupe (French West Indies) releases sulfur bacteria in shallow environment of the Bay. A previous study reveals ingestion of those bacteria by opportunist species (sea urchin and fish species). In the present study, ten species with different diet and feeding mode were sampled close to the release channel of the geothermal plant and in a control station in order to simultaneously determine their stable isotopes (δ13C and δ15N) and radiocarbon compositions. Compared to models using Δ14C data, models using δ13C and δ15N data underestimate the role of bacteria in diet of urchin and fish species whereas this role is overestimated for all other species. Compared to previous models, radiocarbon would give more realistic and reliable results than the classical use of stable isotope. This study confirms the utility of radiocarbon in food web ecology, particularly at the ecosystems having food sources with contrasting Δ14C values

ESR and Radiocarbon Dating of Gut Strings from Early Plucked Instruments

Early European plucked instruments have recently experienced a great revival, but a few aspects remain unknown (e.g., the gauge of gut strings). Here we report, for the first time, that the electron spin resonance (ESR) signal intensity of oxidized iron, Fe(III), from gut strings at g = 2 increases linearly with age within a few hundred years. The signal increase in the remaining old strings on early instruments can be used to judge if they are as old as or younger than the instrument. Obtaining the authenticity information of gut strings contributes to the revival of the old instruments and the music