Brett D Walker

Biographic Data

ID5598448
NAMEBrett D Walker
GIVEN NAMESBrett D
FAMILY NAMEWalker
SIGNATUREWALKER B D
ORCID0000-0003-4904-826X
VERIFIEDYes
TOTAL WORKS5
TOTAL CITATIONS7
AUTHOR COUNT5
EDITOR COUNT0
FIRST PUBLICATION YEAR2013
LATEST PUBLICATION YEAR2022
H-INDEX2

  • Marine Organic Carbon and Radiocarbon—present and Future Challenges

    Open AccessEllen R M Druffel, Steven R Beaupré et al.ARTICLERadiocarbon2022References: 109

    We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Δ 14 C 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…

  • UV Photochemical Oxidation and Extraction of Marine Dissolved Organic Carbon at UC Irvine

    Open AccessBrett D Walker, Steven R Beaupré et al.ARTICLERadiocarbon2019Cited by: 2References: 16

    The first ultraviolet photochemical oxidation (UVox) extraction method for marine dissolved organic carbon (DOC) as CO 2 gas was established by Armstrong and co-workers in 1966. Subsequent refinement of the UVox technique has co-evolved with the need for high-precision isotopic (Δ 14 C, δ 13 C) analysis and smaller sample size requirements for accelerator mass spectrometry radiocarbon (AMS 14 C) measurements. The UVox line at UC Irvine was establ…

  • Temporal Variability of Dissolved Organic Radiocarbon in the Deep North Pacific Ocean

    Open AccessEllen R M Druffel, Sheila Griffin et al.ARTICLERadiocarbon2018References: 31

    We report marine dissolved organic carbon (DOC) ∆ 14 C from seawater collected from the North central Pacific Ocean (NCP) in 2015. These measurements show DOC ∆ 14 C values averaged –235±5‰ ( n =3) in the mixed layer (24–81 m) and –544±5‰ ( n =5) in the deep water (1500–5139 m). A comparison of these data with two previously published DOC ∆ 14 C profiles from the NCP in 1985 and 1987 reveals that deep DOC ∆ 14 C values have decreased. We discuss …

  • Effect of Acidified Versus Frozen Storage on Marine Dissolved Organic Carbon Concentration and Isotopic Composition

    Open AccessBrett D Walker, Sheila Griffin et al.ARTICLERadiocarbon2017Cited by: 1References: 23

    The standard procedure for storing/preserving seawater dissolved organic carbon (DOC) samples after field collection is by freezing (–20°C) until future analysis can be made. However, shipping and receiving large numbers of these samples without thawing presents a significant logistical problem and large monetary expense. Access to freezers can also be limited in remote field locations. We therefore test an alternative method of preserving and st…

  • Total Uncertainty of Radiocarbon Measurements of Marine Dissolved Organic Carbon and Methodological Recommendations

    Open AccessEllen R M Druffel, Ellen Druffel et al.ARTICLERadiocarbon2013Cited by: 4References: 6

    We report results of duplicate measurements of dissolved organic carbon concentrations ([DOC] as μM) and Δ 14 C in seawater in order to assess the total uncertainty of reported [DOC] and Δ 14 C measurements via the UV oxidation method. In addition, pure International Atomic Energy Agency standards analyzed over a 4-yr period are evaluated. We find the total uncertainty of Δ 14 C measurements to be ±4.0. However, in samples that were thawed, subsa…