Lewis Christian B.

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Lewis
First Name
Christian B.
ORCID
0000-0003-0358-6169

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  • Article
    Marine organic carbon and radiocarbon – present and future challenges
    (Cambridge University Press, 2022-01-25) Druffel, Ellen R. M. ; Beaupre, Steven R. ; Grotheer, Hendrik ; Lewis, Christian B. ; McNichol, Ann P. ; Mollenhauer, Gesine ; Walker, Brett D.
    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.
  • Article
    Dissolved organic radiocarbon in the eastern Pacific and Southern Oceans
    (American Geophysical Union, 2021-05-24) Druffel, Ellen R. M. ; Griffin, Sheila ; Lewis, Christian B. ; Rudresh, Megha ; Garcia, Noreen G. ; Key, Robert M. ; McNichol, Ann P. ; Hauksson, Niels E. ; Walker, Brett D.
    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).
  • Dataset
    Concentrations and radiocarbon signatures of SPE-DOC extracted from seawater samples on GO-SHIP cruises P16N, P18, and IO7N in the North Pacific, Eastern Pacific, and Western Indian Oceans
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-01-19) Druffel, Ellen R.M. ; Lewis, Christian
    This dataset includes concentrations and radiocarbon signatures of solid-phase extracted dissolved organic carbon (SPE-DOC) from seawater samples. Water samples were collected on GO-SHIP cruises P16N, P18, and IO7N in the North Pacific, Eastern Pacific, and Western Indian Oceans from 2015 to 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/853101
  • Article
    Dissolved Organic Radiocarbon in the West Indian Ocean
    (American Geophysical Union, 2023-10-02) Druffel, Ellen R. M. ; Lewis, Christian B. ; Griffin, Sheila ; Flaherty, Alessandra ; Rudresh, Megha ; Hauksson, Niels E. ; Key, Robert M. ; McNichol, Ann P. ; Hwang, Jeomshik ; Walker, Brett D.
    We report marine dissolved organic carbon (DOC) concentrations, and DOC Δ14C and δ13C in seawater collected from the West Indian Ocean during the GO-SHIP I07N cruise in 2018. We find bomb 14C in DOC from the upper 1,000 m of the water column. There is no significant change in ∆14C of DOC in deep water northward, unlike that of dissolved inorganic carbon (DIC), suggesting that transport of deep water northward is not controlling the 14C age of DOC. Variability of DOC ∆14C, including high values in the deep waters, is more pronounced than in other oceans, suggesting that dissolution of surface derived particulate organic carbon is a source of modern carbon to deep DOC in the West Indian Ocean. Low δ13C are present at two of the five stations studied, suggesting a source of low δ13C DOC, or additional microbial utilization of deep DOC.