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  • Association for the Sciences of Limnology and Oceanography  (2)
  • Springer Science and Business Media LLC  (1)
  • 1
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    Intercalibration studies of short-lived thorium-234 in the water column and marine particles (2014)
    Association for the Sciences of Limnology and Oceanography
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 10 (2012): 631-644, doi:10.4319/lom.2012.10.631.
    Beschreibung: 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 intercalibration 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% to 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 〉 51 μm size particles, indicating particle loss during the pumping process. No change in 234Th activities on small particles was observed with increasing flow-rates. 234Th intercalibration 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.
    Beschreibung: This research is funded by NSF Chemical Oceanography program. LM will like to thank Fisheries and Oceans Canada for support. PM is supported through ICREA Academia funded by Generalitat de Catalunya. The International Atomic Energy Agency is grateful to the Government of the Principality of Monaco for the support provided to its Environment Laboratories.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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    ARTIKEL (OA)
  • 2
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    Alpha radiation from polymetallic nodules and potential health risks from deep-sea mining (2023)
    Springer Science and Business Media LLC
    In:  EPIC3Scientific Reports, Springer Science and Business Media LLC, 13(1), pp. 7985-7985, ISSN: 2045-2322
    Details
    Publikationsdatum: 2023-06-27
    Beschreibung: In search for critical elements, polymetallic nodules at the deep abyssal seafloor are targeted for mining operations. Nodules efficiently scavenge and retain several naturally occurring uranium-series radioisotopes, which predominantly emit alpha radiation during decay. Here, we present new data on the activity concentrations of thorium-230, radium-226, and protactinium-231, as well as on the release of radon-222 in and from nodules from the NE Pacific Ocean. In line with abundantly published data from historic studies, we demonstrate that the activity concentrations for several alpha emitters are often higher than 5 Bq g−1 at the surface of the nodules. These observed values can exceed current exemption levels by up to a factor of 1000, and even entire nodules commonly exceed these limits. Exemption levels are in place for naturally occurring radioactive materials (NORM) such as ores and slags, to protect the public and to ensure occupational health and radiation safety. In this context, we discuss three ways of radiation exposure from nodules, including the inhalation or ingestion of nodule fines, the inhalation of radon gas in enclosed spaces and the potential concentration of some radioisotopes during nodule processing. Seen in this light, inappropriate handling of polymetallic nodules poses serious health risks.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
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  • 3
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    GEOTRACES intercalibration of 230Th, 232Th, 231Pa, and prospects for 10Be (2014)
    Association for the Sciences of Limnology and Oceanography
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 10 (2012): 179-213, doi:10.4319/lom.2012.10.179.
    Beschreibung: Nineteen labs representing nine nations participated in the GEOTRACES intercalibration initiative that determined concentrations of 232Th, 230Th, 231Pa, or 10Be in seawater, suspended particles or sediments. Results generally demonstrated good agreement among labs that analyzed marine sediments. Two sets of seawater samples, aliquots of particulate material filtered in situ, and/or aliquots of biogenic sediments were distributed to participating labs. Internal consistency among participating labs improved substantially between the first and second set of seawater samples. Contamination was a serious problem for 232Th. Standard Niskin bottles introduced no detectable contamination, whereas sample containers, reagents, and labware were implicated as sources of contamination. No detectable differences in concentrations of dissolved 232Th, 230Th, or 231Pa were observed among samples of seawater filtered through Nuclepore, Supor, or QMA (quartz) filters with pore diameters ranging between 0.4 and 1.0 μm. Isotope yield monitors equilibrate with dissolved Th in seawater on a time scale of much less than 1 day. Samples of filtered seawater acidified to a pH between 1.7 and 1.8 experienced no detectable loss of dissolved Th or Pa during storage for up to 3 years. The Bermuda Atlantic Time Series station will serve as a GEOTRACES baseline station for future intercalibration of 232Th and 230Th concentrations in seawater. Efforts to improve blanks and standard calibration are ongoing, as is the development of methods to determine concentrations of particulate nuclides, tests of different filtration methods, and an increasing awareness of the need to define protocols for reporting uncertainties.
    Beschreibung: Funding for sample collection and for the coordination of this intercalibration of Th isotopes, 231Pa and 10Be was provided by the U.S. NSF (to Anderson, Moran, and Edwards). Funding from NSF (to R. Francois and to K. Buesseler) also supported the collection of previously unpublished data that are presented here.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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    ARTIKEL (OA)
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