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  • Archean atmosphere  (2)
  • Fish  (1)
  • Elsevier  (3)
  • 2020-2023  (3)
  • 1
    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 Broadley, M., Byrne, D., Ardoin, L., Almayrac, M., Bekaert, D., & Marty, B. High precision noble gas measurements of hydrothermal quartz reveal variable loss rate of Xe from the Archean atmosphere. Earth and Planetary Science Letters, 588, (2022): 117577, https://doi.org/10.1016/j.epsl.2022.117577.
    Description: Determining the composition of the Archean atmosphere and oceans is vital to understanding the environmental conditions that existed on the surface of the early Earth. The analysis of atmospheric remnants in fluid inclusions trapped in Archean-aged samples has shown that the Xe isotopic signature of the Archean atmosphere progressively evolved via mass-dependent fractionation, arriving at a modern atmospheric composition around the Archean-Proterozoic transition. The mechanisms driving this evolution are however not well constrained, and it is not yet clear whether the evolution proceeded continuously or via episodic bursts. Providing further constraints on the evolution of Xe in the Archean atmosphere is hampered by the limited amounts of atmospheric gas trapped within fluid inclusions during mineral formation, which impacts the precision at which the Archean atmosphere can be determined. Here, we develop a new crush-and-accumulate extraction technique that enables the heavy noble gases (Ar, Kr and Xe) released from crushing large quantities of hydrothermal quartz to be accumulated and analysed to a higher precision than was previously possible. Using this new technique, we re-evaluate the composition of atmospheric gases trapped within fluid inclusions of 3.3 Ga quartz samples from Barberton, South Africa. We find that the Xe isotopic signature is fractionated by +10.3 ± 1.0‰u−1 (2 SE) relative to modern atmosphere, which is within uncertainty of, but slightly lower than, the previous determination of 12.9 ± 2.4‰u−1 for this sample (Avice et al., 2017). We show for the first time that the Kr/Xe ratio measured within Archean quartz samples is enriched in Xe compared to the modern atmosphere, demonstrating that the atmosphere has lost Xe since the Archean. This further reinforces the proposal of atmospheric escape as the primary mechanism for Earth's Xe loss. We further show that the atmospheric Kr/Xe and Xe isotope fractionation recorded in the Barberton quartz at 3.3 Ga is incompatible with a model describing atmospheric loss at a continuous rate under a constant fractionation factor. This gives credence to numerical models of hydrodynamic escape, which suggest that Xe was lost from the Archean atmosphere in episodic bursts rather than at a constant rate. Refining the evolution curve of atmospheric Xe isotopes using the new technique presented here has the potential to shed light on discrete atmospheric events that punctuated the evolution of the Archean Earth and accompanied the evolution of life.
    Description: This study was supported by the European Research Council (PHOTONIS project, grant agreement No. 695618). This is CRPG contribution #2820.
    Keywords: Archean atmosphere ; Noble gases ; Xenon ; Atmospheric escape
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Almayrac, M. G., Broadley, M. W., Bekaert, D. V., Hofmann, A., & Marty, B. Possible discontinuous evolution of atmospheric xenon suggested by Archean barites. Chemical Geology, 581, (2021): 120405, https://doi.org/10.1016/j.chemgeo.2021.120405.
    Description: The Earth's atmosphere has continually evolved since its formation through interactions with the mantle as well as through loss of volatile species to space. Atmospheric xenon isotopes show a unique and progressive evolution during the Archean that stopped around the Archean-Proterozoic transition. The Xe isotope composition of the early atmosphere has been previously documented through the analysis of fluid inclusions trapped within quartz and barite. Whether this evolution was continuous or not is unclear, requiring additional analyses of ancient samples, which may potentially retain remnants of the ancient atmosphere. Here we present new argon, krypton and xenon isotopic data from a suite of Archean and Proterozoic barites ranging in age from 3.5 to 1.8 Ga, with the goal of providing further insights in to the evolution of atmospheric Xe, whilst also outlining the potential complications that can arise when using barites as a record of past atmospheres. Xenon released by low temperature pyrolysis and crushing of two samples which presumably formed around 2.8 and 2.6 Ga show Xe isotope mass dependent fractionation (MDF) of 11‰.u−1 and 3.4‰.u−1, respectively, relative to modern atmosphere. If trapped Xe is contemporaneous with the respective formation age, the significant difference in the degree of fractionation between the two samples provides supporting evidence for a plateau in the MDF-Xe evolution between 3.3 Ga and 2.8 Ga, followed by a rapid evolution at 2.8–2.6 Ga. This sharp decrease in MDF-Xe degree suggests the potential for a discontinuous temporal evolution of atmospheric Xe isotopes, which could have far reaching implications regarding current physical models of the early evolution of the Earth's atmosphere.
    Description: This work was funded by the ERC grant No. 695618 to B.M. We thank the S.A.R.M for providing elemental bulk analyses of the barites. We thank Laurent Zimmerman for technical mentorship and assistance.
    Keywords: Archean barite ; Noble gases ; Xenon anomalies ; Archean atmosphere
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-26
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Celander, M. C., Goldstone, J. V., Brun, N. R., Clark, B., Jayaraman, S., Nacci, D., & Stegeman, J. J. Resistance to Cyp3a induction by polychlorinated biphenyls, including non-dioxin-like PCB153, in gills of killifish (Fundulus heteroclitus) from New Bedford Harbor. Environmental Toxicology and Pharmacology, 83, (2021): 103580. doi: 10.1016/j.etap.2020.103580.
    Description: Previous reports suggested that non-dioxin-like (NDL) PCB153 effects on cytochrome P450 3A (Cyp3a) expression in Atlantic killifish (Fundulus heteroclitus) gills differed between F0 generation fish from a PCB site (New Bedford Harbor; NBH) and a reference site (Scorton Creek; SC). Here, we examined effects of PCB153, dioxin-like (DL) PCB126, or a mixture of both, on Cyp3a56 mRNA in killifish generations removed from the wild, without environmental PCB exposures. PCB126 effects in liver and gills differed between populations, as expected. Gill Cyp3a56 was not affected by either congener in NBH F2 generation fish, but was induced by PCB153 in SC F1 fish, with females showing a greater response. PCB153 did not affect Cyp3a56 in liver of either population. Results suggest a heritable resistance to NDL-PCBs in killifish from NBH, in addition to that reported for DL PCBs. Induction of Cyp3a56 in gills may be a biomarker of exposure to NDL PCBs in fish populations that are not resistant to PCBs.
    Description: This study was supported by the sabbatical program from the Faculty of Science at the University of Gothenburg (MC), and by the Swiss National Science Foundation P2EZP2-165200 (NRB). The study was supported in part by the Superfund Hazardous Substances Research Program at Boston University NIH P42ES007381 (JVG, JJS). This research was also funded partly by the US Environmental Protection Agency (SJ, DN), including an appointment (BC) with the Postdoctoral Research Program at the US Environmental Protection (US-EPA) Office of Research and Development administered by the Oak Ridge Institute for Science and Education (ORISE), through Interagency Agreement No. DW92429801 between the US Department of Energy and the US-EPA. The contents do not reflect the views of the US-EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use by the US-EPA. We thank Rene Francolini at the Woods Hole Oceanographic Institutions for excellent technical assistance and Dr. Sibel Karchner and Dr. Mark Hahn at the Woods Hole Oceanographic Institutions for valuable discussions and comments on the manuscript.
    Keywords: PCB153 ; Fish ; Gills ; Cyp3a ; Resistance
    Repository Name: Woods Hole Open Access Server
    Type: Article
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