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  • Radiocarbon  (13)
  • Coral  (2)
  • 13C  (1)
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  • 1
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 125 (2017): 26-39, doi:10.1016/j.dsr.2017.04.006.
    Description: Bamboo corals, long-lived cold water gorgonin octocorals, offer unique paleoceanographic archives of the intermediate ocean. These Isididae corals are characterized by alternating gorgonin nodes and high Mg-calcite internodes, which synchronously extend radially. Bamboo coral calcite internodes have been utilized to obtain geochemical proxy data, however, growth rate uncertainty has made it difficult to construct precise chronologies for these corals. Previous studies have relied upon a tie point from records of the anthropogenic Δ14C bomb spike preserved in the gorgonin nodes of live-collected corals to calculate a mean radial extension rate for the outer ~50 years of skeletal growth. Bamboo coral chronologies are typically constructed by applying this mean extension rate to the entire coral record, assuming constant radial extension with coral age. In this study, we aim to test this underlying assumption by analyzing the organic nodes of six California margin bamboo corals at high enough resolution (〈0.5 mm) to identify the Δ14C bomb spike, including two tie points at 1957 and 1970, plus coral collection date (2007.5) for four samples. Radial extension rates between tie points ranged from 10 to 204 μm/year, with a decrease in growth rate evident between the 1957-1970 and 1970- 2007.5 periods for all four corals. A negative correlation between growth rate and coral radius (r = -0.7; p = 0.03) was determined for multiple bamboo coral taxa and individuals from the California margin, demonstrating a decline in radial extension rate with specimen age and size. To provide a mechanistic basis for these observations, a simple mathematical model was developed based on the assumption of a constant increase in circular cross sectional area with time to quantify this decline in radial extension rate with coral size between chronological tie points. Applying the area-based model to our Δ14C bomb spike time series from individual corals improves chronology accuracy for all live-collected corals with complete Δ14C bomb spikes. Hence, this study provides paleoceanographers utilizing bamboo corals with a method for reducing age model uncertainty within the anthropogenic bomb spike era (~1957-present). Chronological uncertainty is larger for the earliest portion of coral growth, particularly for skeleton precipitated prior to bomb spike tie points, meaning age estimations for samples living before 1957 remain uncertain. Combining this technique with additional chronological markers could improve age models for an entire bamboo coral. Finally, the relative consistency in growth rate in similarly-aged corals of the same depth and location supports the hypothesis that skeletal growth may be limited by local environmental conditions.
    Description: This research was made possible by National Science Foundation Award #1420984 to M. LaVigne and a Clare Boothe Luce Fellowship to M. Frenkel.
    Keywords: Bamboo coral ; Gorgonin ; Paleoceanography ; Chronologies ; Radiocarbon ; Growth rate ; 14C nuclear bomb spike
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2010. 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 115 (2010): D10301, doi:10.1029/2009JD012810.
    Description: Compound specific radiocarbon analyses of atmospheric formaldehyde are reported as fraction modern (Fm) for a limited number of winter and summer air samples collected in coastal southern New England in 2007. The 11 of 13 samples with Fm 〈 0.2 were collected under the influence of the semipermanent Bermuda high-pressure system with transport from the Washington, D. C., to New York City urban corridor. The two samples with Fm 〉 0.2 (max ∼ 0.35) were collected on days with strong northwesterly flow and the least urban impact. The Fm data were combined with VOC observations from the Rhode Island Department of Environmental Management, estimates of oxygenated VOC (OVOC), and back trajectories to interpret the relative contributions of biogenic and fossil carbon sources. It is argued that CH2O sources were dominated by pollutant VOCs and OVOCs from upwind coastal cities as opposed to more local biogenic VOCs at the times of sample collection.
    Description: This research was supported by a graduate student internship program at WHOI National Ocean Sciences Accelerator Mass Spectrometry Facility (NSF OCE‐9807266) and by NASA project NNG04GB38G.
    Keywords: Formaldehyde ; Radiocarbon ; Volatile organic compounds ; Oxygenated volatile organic compounds ; Ozone ; Troposphere
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 28 (2013): 227–236, doi:10.1002/palo.20023.
    Description: During the past 40,000 years, global climate has moved into and out of a full glacial period, with the deglaciation marked by several millennial-scale rapid climate change events. Here we investigate the ecological response of deep-sea coral communities to both glaciation and these rapid climate change events. We find that the deep-sea coral populations of Desmophyllum dianthus in both the North Atlantic and the Tasmanian seamounts expand at times of rapid climate change. However, during the more stable Last Glacial Maximum, the coral population globally retreats to a more restricted depth range. Holocene populations show regional patterns that provide some insight into what causes these dramatic changes in population structure. The most important factors are likely responses to climatically driven changes in productivity, [O2] and [CO32–].
    Description: 2013-11-30
    Keywords: Radiocarbon ; Coral ; Glacial
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. 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 44 (2017): 2407–2415, doi:10.1002/2016GL071348.
    Description: We present concentration and isotopic profiles of total, size, and polarity fractionated dissolved organic carbon (DOC) from Station ALOHA (A Long-term Oligotrophic Habitat Assessment), an oligotrophic site in the North Pacific Ocean. The data show that, between the surface and 3500 m, low molecular weight (LMW) hydrophilic DOC, LMW hydrophobic DOC, and high molecular weight (HMW) DOC constitute 22–33%, 45–52%, and 23–35% of DOC, respectively. LMW hydrophilic DOC is more isotopically depleted (δ13C of −23.9‰ to −31.5‰ and Δ14C of −304‰ to −795‰; mean age of 2850 to 15000 years) than the LMW hydrophobic DOC (δ13C of −22‰ to −23‰ and Δ14C of −270‰ to −568‰; 2470 to 6680 years) and HMW DOC (δ13C of ~−21‰ and Δ14C of −24‰ to −294‰; 135–2700 years). Our analyses suggest that a large fraction of DOC may be derived from allochthonous sources such as terrestrial and hydrothermal DOC and cycle on much longer time scales of 〉10000 years or enter the ocean as preaged carbon.
    Description: NSF Cooperative Agreement for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility Grant Number: OCE-0753487; Gordon and Betty Moore Foundation Grant Numbers: GBMF3298, GBMF3794; Simons Foundation Grant Number: 329108
    Description: 2017-09-07
    Keywords: Carbon cycling ; Carbon isotopes ; Radiocarbon ; Biogeochemical cycles
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geophysical Research Letters 45 (2018): 8425-8434, doi:10.1029/2018GL078904.
    Description: Compound‐specific radiocarbon analysis was performed on different grain‐size fractions of surficial sediments to examine and compare lateral transport times (LTTs) of organic carbon. 14C aging of long‐chain leaf wax fatty acids along two dispersal pathways of fluvially derived material on adjacent continental margins implies LTTs over distances of ~30 to 500 km that range from hundreds to thousands of years. The magnitude of aging differs among grain size fractions. Our finding suggests that LTTs vary both temporally and spatially as a function of the specific properties of different continental shelf settings. Observations suggest that 14C aging is widespread during lateral transport over continental shelves, with hydrodynamic particle sorting inducing age variations among organic components residing in different grain sizes. Consideration of these phenomena is of importance for understanding carbon cycle processes and interpretation on sedimentary records on continental margins.
    Description: National Natural Science Foundation of China Grant Numbers: 41520104009, 41521064; MOE; JSPS Grant Numbers: A‐1003, 2‐1304, B‐0904, B‐0903, 22310014, 23651021, 25550020; NIES; SNSF Grant Number: 200021_140850
    Keywords: Radiocarbon ; Lateral particle transport time ; Organic carbon aging ; Continental shelf sediments ; Grain size fractions
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
    Publication Date: 2022-10-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Druffel, E. R. M., Griffin, S., Wang, N., Garcia, N. G., McNichol, A. P., Key, R. M., & Walker, B. D. Dissolved organic radiocarbon in the central Pacific Ocean. Geophysical Research Letters, 46(10), (2019):5396-5403, doi:10.1029/2019GL083149.
    Description: We report marine dissolved organic carbon (DOC) concentrations, and DOC ∆14C and δ13C values in seawater collected from the central Pacific. Surface ∆14C values are low in equatorial and polar regions where upwelling occurs and high in subtropical regions dominated by downwelling. A core feature of these data is that 14C aging of DOC (682 ± 86 14C years) and dissolved inorganic carbon (643 ± 40 14C years) in Antarctic Bottom Water between 54.0°S and 53.5°N are similar. These estimates of aging are minimum values due to mixing with deep waters. We also observe minimum ∆14C values (−550‰ to −570‰) between the depths of 2,000 and 3,500 m in the North Pacific, though the source of the low values cannot be determined at this time.
    Description: We thank Jennifer Walker, Xiaomei Xu, and Dachun Zhang for their help with the stable carbon isotope measurements; John Southon and staff of the Keck Carbon Cycle AMS Laboratory for their assistance and advice; the support of chief scientists Samantha Siedlecki, Molly Baringer, Alison Macdonald, and Sabine Mecking; the guidance of Jim Swift and Dennis Hansell for shared ship time; and Sarah Bercovici for collecting water on the GoA cruise. We appreciate the comments of Christian Lewis and Niels Hauksson on this manuscript. This work was supported by NSF (OCE‐141458941 to E. R. M. D. and OCE‐0824864, OCE‐1558654, and Cooperative Agreement OCE1239667 to R. M. K. and A. P. M.), the Fred Kavli Foundation, the Keck Carbon Cycle AMS Laboratory, and the NSF/NOAA‐funded GO‐SHIP Program. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program (to B. D. W.) and an American Chemical Society Petroleum Research Fund New Directions grant (55430‐ND2 to E. R. M. D. and B. D. W.). Data from the P16N cruises are available in Table S2 in the Supporting Information and at the Repeat Hydrography Data Center at the CCHDO website (http://cdiac.esd.ornl.gov/oceans/index.html) using the expo codes 3RO20150329, 3RO20150410, and 3RO20150525. There are no real or perceived financial conflicts of interests for any author.
    Description: 2019-11-02
    Keywords: Dissolved organic carbon ; Radiocarbon ; Pacific Ocean ; Dissolved inorganic carbon ; Deep ocean circulation ; AABW
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
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    Cambridge University Press
    Publication Date: 2022-10-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in McNichol, A., Key, R., & Guilderson, T. Global ocean radiocarbon programs. Radiocarbon, (2022): 1–13, https://doi.org/10.1017/rdc.2022.17.
    Description: The importance of studying the radiocarbon content of dissolved inorganic carbon (DI14C) in the oceans has been recognized for decades. Starting with the GEOSECS program in the 1970s, 14C sampling has been a part of most global survey programs. Early results were used to study air-sea gas exchange while the more recent results are critical for helping calibrate ocean general circulation models used to study the effects of climate change. Here we summarize the major programs and discuss some of the important insights the results are starting to provide.
    Description: Authors received funding from the National Science Foundation OCE-85865400 (APM) and a Woods Hole Oceanographic Technical Staff Award (APM).
    Keywords: Dissolved inorganic carbon ; Ocean models ; Oceanography ; Radiocarbon
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2019. 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: Biogeosciences 124(8), (2019): 2582-2594, doi: 10.1029/2019JG005107.
    Description: To assess the influences of carbon sources and transport processes on the 14C age of organic matter (OM) in continental margin sediments, we examined a suite of samples collected along a river‐shelf‐deep ocean transect in the East China Sea (ECS). Ramped pyrolysis‐oxidiation was conducted on suspended particulate matter in the Yangtze River and on surface sediments from the ECS shelf and northern Okinawa Trough. 14C ages were determined on OM decomposition products within different temperature windows. These measurements suggest that extensive amounts of pre‐old (i.e., millennial age) organic carbon (OC) are subject to degradation within and beyond the Yangtze River Delta, and this process is accompanied by an exchange of terrestrial and marine OM. These results, combined with fatty acid concentration data, suggest that both the nature and extent of OM preservation/degradation as well as the modes of transport influence the 14C ages of sedimentary OM. Additionally, we find that the age of (thermally) refractory OC increases during across‐shelf transport and that the age offset between the lowest and highest temperature OC decomposition fractions also increases along the shelf‐to‐trough transect. Amplified interfraction spread or 14C heterogeneity is the greatest in the Okinawa Trough. Aged sedimentary OM across the transect may be a consequence of several reasons including fossil OC input, selective degradation of younger OC, hydrodynamic sorting processes, and aging during lateral transport. Consequently, each of them should be considered in assessing the 14C results of sedimentary OM and its implications for the carbon cycle and interpretation of sedimentary records.
    Description: This study was supported by Doc. Mobility Fellowship (P1EZP2_159064; R. B.) from the Swiss National Science Foundation (SNSF). This study was also supported by SNF “CAPS‐LOCK” project 200021_140850 (T. I. E.), by the National Natural Science Foundation of China (NSFC; grants 41520104009 and 41630966, M. Z.), and by the “111” project (B13030). We are grateful for support of the NOSAMS staff in the execution of this project. We also appreciate the assistance from Yushuang Zhang (Ocean University of China) at NOSAMS and members of the Laboratory for Ion Beam Physics at ETH Zurich for AMS measurements. We acknowledge Lei Xing, Haidong Zhang, Guodong Song, Meng Yu, Yonghao Jia, and Shanshan Duan (Ocean University of China) for sampling assistance on the cruises. Assistance at sea by the crews of R/V Dongfanghong II and R/V Hakuhu Maru is also acknowledged. Readers can access or find the data from figures and tables in the supporting information.
    Keywords: Radiocarbon ; Carbon cycle ; Sediments ; Organic carbon ; Hydrodynamic processes
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 9
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2021. 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 48(10), (2021): e2021GL092904, https://doi.org/10.1029/2021GL092904.
    Description: We report marine dissolved organic carbon (DOC) concentrations, and DOC Δ14C and δ13C values in seawater collected from the Southern Ocean and eastern Pacific GOSHIP cruise P18 in 2016/2017. The aging of 14C in DOC in circumpolar deep water northward from 69°S to 20°N was similar to that measured in dissolved inorganic carbon in the same samples, indicating that the transport of deep waters northward is the primary control of 14C in DIC and DOC. Low DOC ∆14C and δ13C measurements between 1,200 and 3,400 m depth may be evidence of a source of DOC produced in nearby hydrothermal ridge systems (East Pacific Rise).
    Description: This work was supported by NSF (OCE-1458941 and OCE-1951073 to Ellen R. M. Druffel), Fred Kavli Foundation, Keck Carbon Cycle AMS Laboratory, NSF/NOAA funded GO-SHIP Program, Canada Research Chairs program (to Brett D. Walker) and American Chemical Society Petroleum Research Fund New Directions (55,430-ND2 to Ellen R. M. Druffel and Brett D. Walker).
    Description: 2021-11-24
    Keywords: 13C ; Carbon cycle ; Circumpolar deep water ; Dissolved inorganic carbon ; Dissolved organic carbon ; Radiocarbon
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
    Publication Date: 2022-10-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Druffel, E., Beaupre, S., Grotheer, H., Lewis, C., McNichol, A., Mollenhauer, G., & Walker, B. Marine organic carbon and radiocarbon – present and future challenges. Radiocarbon, (2022): 1-17, https://doi.org/10.1017/RDC.2021.105.
    Description: We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Δ14C measurements reveal information about the cycling time and sources of DOC in the ocean, yet they are time consuming and need to be streamlined. To further elucidate the cycling of DOC, various fractions have been separated from bulk DOC, through solid phase extraction of DOC, and ultrafiltration of high and low molecular weight DOC. Research using 14C of DOC and particulate organic C separated into organic fractions revealed that the acid insoluble fraction is similar in 14C signature to that of the lipid fraction. Plans for utilizing this methodology are described. Studies using compound specific radiocarbon analyses to study the origin of biomarkers in the marine environment are reviewed and plans for the future are outlined. Development of ramped pyrolysis oxidation methods are discussed and scientific questions addressed. A modified elemental analysis (EA) combustion reactor is described that allows high particulate organic C sample throughput by direct coupling with the MIniCArbonDAtingSystem.
    Keywords: CSRA ; Dissolved organic carbon ; Methodology ; Organic carbon ; Radiocarbon
    Repository Name: Woods Hole Open Access Server
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