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  • AMER SOC LIMNOLOGY OCEANOGRAPHY  (1)
  • Elsevier  (1)
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  • 1
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    Intercalibration studies of short lived Thorium-234 in the water column and marine particles (2012)
    AMER SOC LIMNOLOGY OCEANOGRAPHY
    In:  EPIC3Limnology and Oceanography-Methods, AMER SOC LIMNOLOGY OCEANOGRAPHY, 10, pp. 631-644, ISSN: 1541-5856
    Details
    Publication Date: 2019-07-16
    Description: Intercomparision of 234Th measurements in both water and particulate samples was carried out between 15 laboratories worldwide, as a part of GEOTRACES inter-calibration program. Particulate samples from four different stations namely BATS (both shallow and deep) and shelf station (shallow) in Atlantic and SAFE (both shallow and deep) and Santa Barbara station (shallow) in Pacific were used in the effort. Particulate inter-calibration results indicate good agreement between all the participating labs with data from all labs falling within the 95% confidence interval around the mean for most instances. Filter type experiments indicate no significant differences in 234Th activities between filter types and pore sizes (0.2–0.8 μm). The only exception are the quartz filters which are associated with 10-20% higher 234Th activities attributed to sorption of dissolved 234Th. Flow rate experiments showed a trend of decreasing 234Th activities with increasing flow rates (2-9 L min-1) for 〉51μm size particles, indicating particle loss during the pumping process. No change in 234Th activities on small particles was observed with increasing flow-rates. 234Th inter-calibration results from deep water samples at SAFe station indicate a variability of 〈3% amongst labs while dissolved 234Th data from surface water at Santa Barbara Station show a less robust agreement, possibly due to the loss of 234Th from decay and large in-growth corrections as a result of long gap between sample collection and processing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
  • 2
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    Particulate organic carbon export fluxes estimates by 234Th238U disequilibrium in the oxygen minimum zone off the Peruvian coast (2023)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: The Peruvian upwelling zone is one of the most productive marine ecosystems in the world with a spectacular, pronounced oxygen minimum zone (OMZ). Globally OMZs are increasing in size and intensity with far-reaching consequences for the marine biological carbon pump and carbon export; thus, these zones need to be carefully monitored to be able to understand future climate change impacts. The current study was carried out in 2013 and 2017 to quantify the vertical flux of organic matter exported out of the productive surface layer by measuring 234Thsingle bond238U disequilibria in the water column. Samples were collected in January 2013 and May 2017 along an identical transect located at 12°S off the Peruvian coast near Lima, Peru. Th-234 fluxes ranged from 0 to 2088 ± 95 dpm m−2 d−1 in 2013 and 698 ± 63 to 3648 ± 113 dpm m−2 d−1 in 2017. The corresponding POC fluxes varied between 0 and 164.2 ± 7.9 mg C m−2 d−1 in 2013 and 22.7 ± 2.7 to 133.1 ± 15.2 mg C m−2 d−1 in 2017, with POC fluxes gradually decreasing with distance from the coast. Despite higher POC fluxes, the export efficiencies were found to be extremely low due to high particle remineralization rates observed within the euphotic zone.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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