Efficient radiocarbon measurements on marine and terrestrial samples with single stage Accelerator Mass Spectrometry at the Atmosphere and Ocean Research Institute, University of Tokyo

Yokoyama, Yūsuke; Miyairi, Yosuke; Aze, Takahiro; Sawada, Chikako; Ando, Yuka; Izawa, Satomi; Ueno, Yoshiko; Hirabayashi, Shoko; Fukuyo, Naoto; Ota, Kosuke; Shimizu, Y.; Zeng, Yuning; Liang, Hui; Tsuneoka, Ren; Ando, Kozue; Nemoto, Karin; Obrochta, Stephen; Behrens, Bethany; Tam, Evan; Leggett, Kai; Rzeszewicz, Jian; Huang, Zihan; Kondo, Ryosuke; Nagata, Toshi

doi:10.1016/j.nimb.2022.10.006

Cited by 19 publications

(11 citation statements)

References 21 publications

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“…Finally, the purified CO 2 samples were reduced to graphite on iron powder using pure hydrogen at 630

^{\circ}\mathrm{C}

for 6 hours as described by Yokoyama et al. (2007, 2010), followed by 14 C measurement using the single‐stage accelerator mass spectrometry (AMS) at AORI (Yamane et al., 2019; Yokoyama et al., 2019, 2022b). Results of the 14 C analysis are reported as ∆ 14 C, with the ‰ deviation from the 14 C/ 12 C ratio of a standard with fixed isotopic composition, as defined by Stuiver and Polach (1977).…”

Section: Methodsmentioning

confidence: 99%

“…The DIC ∆ 14 C of seawater is a reliable tracer of water mixing processes (Guilderson et al., 2006; Guilderson & Schrag, 1998; Hirabayashi et al., 2017; Levin & Hesshaimer, 2000; Sweeney et al., 2007). Above‐ground nuclear bomb tests in the Pacific Ocean in the 1940–1960s almost doubled the level of 14 C atoms in the atmosphere compared to that maintained by natural background production rates (Hua et al., 2013, 2022; Yokoyama et al., 2022a, 2022b). Subsequently, a large amount of bomb‐produced 14 C was dissolved in surface water through air‐sea exchange and then gradually penetrated downwards via advection and diffusion.…”

Section: Introductionmentioning

confidence: 98%

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Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

Lan,

Yokoyama,

Hirabayashi

et al. 2024

JGR Oceans

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Kuroshio is an important western boundary current system in the North Pacific subtropical gyre. Mesoscale eddies play an important role in Kuroshio path variations, which significantly affect fisheries, marine navigation, and climate in regions along the Kuroshio path. However, the direct physical impacts of the Kuroshio variabilities on mixing dynamics within the water columns off the southern coast of Japan remain unclear due to the lack of observational records. The radiocarbon (Δ14C) in dissolved inorganic carbon (DIC) of seawater has been used as a reliable tracer of water circulation and mixing processes. Here, we present the high‐resolution dissolved inorganic radiocarbon (DIC ∆14C) measurements for water samples collected during the Kuroshio large‐meander (LM) period in March 2022 to observe the mixing dynamics within the Kuroshio area and elucidate the controls of mixing processes. In the present study, horizontal variations (12–175‰) in DIC Δ14C values were observed between 400 and 1,000 m and were attributed mainly to changes in the depth of isopycnal surfaces associated with mesoscale eddies and the position of the Kuroshio axis. Furthermore, fluctuations in DIC Δ14C values (10–25‰) were observed on the same isopycnal surfaces ( 25.5–27.0), suggesting the occurrence of diapycnal mixing. By comparing this newly obtained data with values previously reported at similar locations, variations in penetration depths of high bomb 14C signals from past observations are found to be mainly caused by changes in the depth of isopycnal surfaces associated with mesoscale eddies and Kuroshio path variations.

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“…Finally, the purified CO 2 samples were reduced to graphite on iron powder using pure hydrogen at 630

^{\circ}\mathrm{C}

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

Lan,

Yokoyama,

Hirabayashi

et al. 2024

JGR Oceans

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“…The age model for the top 225 cm of Core PC01 was obtained through bulk radiocarbon dating using the age-depth modeling program Undatable (Lougheed & Obrochta, 2019). Four sediment samples at a mid-depth of 4, 68, 175, and 225 cm were prepared for analysis following the procedure of Yokoyama et al (2007Yokoyama et al ( , 2010 and measured using the Accelerator Mass Spectrometer at the University of Tokyo (Yokoyama et al, 2019(Yokoyama et al, , 2022. The Marine 20 calibration curve and a marine reservoir effect (ΔR) of 600 ± 250 yr were used.…”

Section: Age-depth Modelmentioning

confidence: 99%

Melting of Totten Glacier, East Antarctica since the Last Glacial Maximum Revealed by Beryllium Isotope and Grain Size of Marine Sediment Records

Huang

Behrens

Miyairi

et al. 2023

Preprint

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The rapidly melting Totten Glacier of East Antarctica drains a basin containing ~3.5 m sea-level rise equivalent of ice, but the Totten Glacier dynamics and interaction with the Southern Ocean since the Last Glacial Maximum is not well understood. To better understand the response of the glacier to present and future climate changes, an accurate reconstruction of the retreat history of the Totten Glacier is needed. Hence, this study uses a multiproxy approach in analyzing beryllium isotopes, the first such record from this location, and grain size of a sediment core collected from the continental slope adjacent to Totten Glacier. The results, when evaluated together with nearby proxy records, reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet began at ~18 ka BP. The rapid deglaciation from ~9 ka BP that followed is assumed to be caused by the intrusion of modified Circumpolar Deep Water to the grounding zone of the Totten Glacier. This intrusion may also be coupled with a weaker Antarctic Slope Current and southward shift of Antarctic easterlies. This result contributes to the body of knowledge regarding the dynamical response of marine-terminating glaciers to climate variability during the last deglaciation.

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“…Finally, the purified CO2 samples are reduced to graphite using iron powder and pure hydrogen at 630°C for 6 hours, following the method described by Yokoyama et al (2007Yokoyama et al ( , 2010. The DIC Δ 14 C values of these samples were then analyzed using a single stage Accelerator Mass Spectrometer (YS-AMS: National Electrostatic Corporation, SAMS) at the AORI, University of Tokyo (Yamane et al, 2019;Yokoyama et al, 2019Yokoyama et al, , 2022b. 12 C and 13 C are measured as well to correct for isotope fractionation effects.…”

Section: The 14 C Analysismentioning

confidence: 99%

“…The radiocarbon content of DIC (expressed as DIC Δ 14 C) in seawater is recognized as an important tracer in oceanographic studies (Levin & Hesshaimer, 2000;Sweeney et al, 2007;Hirabayashi et al, 2017;Kubota et al, 2022). Following the above-ground nuclear bomb tests in the Pacific Ocean during the 1940s-1960s, a substantial amount of bomb-produced 14 C entered the ocean from the atmosphere through air-sea exchange in surface waters and gradually permeated deeper through water advection and diffusion (Hua et al, 2013(Hua et al, , 2022Yokoyama et al, 2022aYokoyama et al, , 2022b. The characteristics of the DIC Δ 14 C distribution underline its importance for the study of oceanic mixing processes and anthropogenic carbon effects caused by the above-ground nuclear bomb tests.…”

Section: Introductionmentioning

confidence: 99%

First dataset of dissolved inorganic radiocarbon in the Tokara Strait

Lan,

Hirabayashi,

Miyairi

et al. 2023

Geochem. J.

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Radiocarbon ( 14 C) has been widely used to understand the ages in archeology and paleoenvironmental sciences. In marine environments, the dissolved inorganic radiocarbon (expressed as DIC Δ 14 C) of seawater has been used as a reliable tracer in the research of carbon cycling and studies in global to regional water mixing. Here, we present the first highresolution dataset of DIC Δ 14 C values in the Tokara Strait collected at eight stations during a cruise on the Research Vessel (R/V) Hakuho-Maru in March 2022. The DIC Δ 14 C ranges from −211‰ to 28‰ in the upper 1200 m depth of the Tokara Strait. High and modern values (bomb 14 C; DIC Δ 14 C ≥ 0‰) were observed above ~400 m depth at station T3 and above 200 m depth at other stations. These are indicative of the influence of anthropogenic carbon from aboveground nuclear bomb tests conducted in the Pacific Ocean during the 1940s to 1960s. The dataset also includes hydrographic information (temperature, salinity, and density), all of which may help interpret the DIC Δ 14 C variations in the Tokara Strait. These datasets are expected to improve our understanding of water mixing processes and the carbon cycle in the Tokara Strait, which has important implications for understanding climate variability.

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Efficient radiocarbon measurements on marine and terrestrial samples with single stage Accelerator Mass Spectrometry at the Atmosphere and Ocean Research Institute, University of Tokyo

Cited by 19 publications

References 21 publications

Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

Melting of Totten Glacier, East Antarctica since the Last Glacial Maximum Revealed by Beryllium Isotope and Grain Size of Marine Sediment Records

First dataset of dissolved inorganic radiocarbon in the Tokara Strait

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