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  • 1
    Online Resource
    Online Resource
    Zinc, carbon, and oxygen isotopic variations associated with the Marinoan deglaciation
    Springer Science and Business Media LLC ; 2023
    In:  Mineralogy and Petrology Vol. 117, No. 2 ( 2023-06), p. 373-386
    Details
    In: Mineralogy and Petrology, Springer Science and Business Media LLC, Vol. 117, No. 2 ( 2023-06), p. 373-386
    Abstract: The "Snowball Earths" were cataclysmic events during the late Neoproterozoic's Cryogenian period (720-635 Ma) in which most, if not all, of Earth’s surface was covered in ice. Paleoenvironmental reconstructions of these events utilize isotopic systems, such as Δ 17 O and barium isotopes of barites. Other isotopic systems, such as zinc (Zn), can reflect seawater composition or environmental conditions (e.g., temperature changes) and biological productivity. We report here a multi-isotopic C, O, and Zn data set for carbonates deposited immediately after the Marinoan glaciation (635 Ma) from the Otavi Group in northern Namibia. In this study, we chemically separated calcite and non-calcitic carbonate phases, finding isotopically distinct carbon and oxygen isotopes. These could reflect changes in the source seawater composition and conditions during carbonate formation. Our key finding is largescale Zn isotopic variations over the oldest parts of the distal foreslope cap carbonate sections. The magnitude of variation is larger than any found throughout post-snowball cap carbonates to date, and in a far shorter sequence. This shows a heretofore undiscovered difficulty for Zn isotopic interpretations. The primary Zn sources are likely to be aeolian or alluvial, associated with the massive deglaciation related run-off from the thawing continent and a greater exposed surface for atmospheric aerosol entrainment. The samples with the lightest Zn isotopic compositions (δ 66 Zn 〈 0.3 ‰) potentially reflect hydrothermally sourced Zn dominating the carbonates’ Zn budget. This finding is likely unique to the oldest carbonates, when the meltwater lid was thinnest and surface waters most prone to upwelling of hydrothermally dominated Snowball Earth brine. On the other hand, local variations could be related to bioproductivity affecting the Zn isotopic composition of the seawater. Similarly, fluctuations in sea-level could bring the depositional site below and above a redoxcline, causing isotopic variations. These variations in Zn isotope ratios preclude the estimation of a global Zn isotopic signature, potentially indicating localized resumption of export production.
    Type of Medium: Online Resource
    ISSN: 0930-0708 , 1438-1168
    URL: Article
    DOI: 10.1007/s00710-023-00827-0
    RVK:
    TE 1000
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 1462900-8
    SSG: 13
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  • 2
    Online Resource
    Online Resource
    A mineral-based origin of Earth’s initial hydrogen peroxide and molecular oxygen
    Proceedings of the National Academy of Sciences ; 2023
    In:  Proceedings of the National Academy of Sciences Vol. 120, No. 13 ( 2023-03-28)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 120, No. 13 ( 2023-03-28)
    Abstract: Terrestrial reactive oxygen species (ROS) may have played a central role in the formation of oxic environments and evolution of early life. The abiotic origin of ROS on the Archean Earth has been heavily studied, and ROS are conventionally thought to have originated from H 2 O/CO 2 dissociation. Here, we report experiments that lead to a mineral-based source of oxygen, rather than water alone. The mechanism involves ROS generation at abraded mineral–water interfaces in various geodynamic processes (e.g., water currents and earthquakes) which are active where free electrons are created via open-shell electrons and point defects, high pressure, water/ice interactions, and combinations of these processes. The experiments reported here show that quartz or silicate minerals may produce reactive oxygen-containing sites (≡SiO•, ≡SiOO•) that initially emerge in cleaving Si–O bonds in silicates and generate ROS during contact with water. Experimental isotope-labeling experiments show that the hydroxylation of the peroxy radical (≡SiOO•) is the predominant pathway for H 2 O 2 generation. This heterogeneous ROS production chemistry allows the transfer of oxygen atoms between water and rocks and alters their isotopic compositions. This process may be pervasive in the natural environment, and mineral-based production of H 2 O 2 and accompanying O 2 could occur on Earth and potentially on other terrestrial planets, providing initial oxidants and free oxygen, and be a component in the evolution of life and planetary habitability.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2221984120
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2023
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
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    Online Resource
    Isotopic Insights into Organic Composition Differences between Supermicron and Submicron Sea Spray Aerosol
    American Chemical Society (ACS) ; 2022
    In:  Environmental Science & Technology Vol. 56, No. 14 ( 2022-07-19), p. 9947-9958
    Details
    In: Environmental Science & Technology, American Chemical Society (ACS), Vol. 56, No. 14 ( 2022-07-19), p. 9947-9958
    Type of Medium: Online Resource
    ISSN: 0013-936X , 1520-5851
    URL: Article
    DOI: 10.1021/acs.est.2c02154
    RVK:
    AR 10100
    Language: English
    Publisher: American Chemical Society (ACS)
    Publication Date: 2022
    detail.hit.zdb_id: 280653-8
    detail.hit.zdb_id: 1465132-4
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  • 4
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    Online Resource
    Detection of deep stratospheric intrusions by cosmogenic 35 S
    Proceedings of the National Academy of Sciences ; 2016
    In:  Proceedings of the National Academy of Sciences Vol. 113, No. 40 ( 2016-10-04), p. 11131-11136
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 113, No. 40 ( 2016-10-04), p. 11131-11136
    Abstract: The extent to which stratospheric intrusions on synoptic scales influence the tropospheric ozone (O 3 ) levels remains poorly understood, because quantitative detection of stratospheric air has been challenging. Cosmogenic 35 S mainly produced in the stratosphere has the potential to identify stratospheric air masses at ground level, but this approach has not yet been unambiguously shown. Here, we report unusually high 35 S concentrations (7,390 atoms m −3 ; ∼16 times greater than annual average) in fine sulfate aerosols (aerodynamic diameter less than 0.95 µm) collected at a coastal site in southern California on May 3, 2014, when ground-level O 3 mixing ratios at air quality monitoring stations across southern California (43 of 85) exceeded the recently revised US National Ambient Air Quality Standard (daily maximum 8-h average: 70 parts per billion by volume). The stratospheric origin of the significantly enhanced 35 S level is supported by in situ measurements of air pollutants and meteorological variables, satellite observations, meteorological analysis, and box model calculations. The deep stratospheric intrusion event was driven by the coupling between midlatitude cyclones and Santa Ana winds, and it was responsible for the regional O 3 pollution episode. These results provide direct field-based evidence that 35 S is an additional sensitive and unambiguous tracer in detecting stratospheric air in the boundary layer and offer the potential for resolving the stratospheric influences on the tropospheric O 3 level.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1609919113
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2016
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
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    Online Resource
    Unexpected high 35 S concentration revealing strong downward transport of stratospheric air during the monsoon transitional period in East Asia
    American Geophysical Union (AGU) ; 2016
    In:  Geophysical Research Letters Vol. 43, No. 5 ( 2016-03-16), p. 2315-2322
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 43, No. 5 ( 2016-03-16), p. 2315-2322
    Abstract: The highest 35 S concentration ever measured for natural sulfate aerosols is reported Strong downward transport from the FT in October brings aged stratospheric air to the PBL Temporal variations in surface O 3 in spring and autumn are in tandem with 35 SO 4 2− concentrations
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Issue
    URL: Article
    DOI: 10.1002/grl.v43.5
    DOI: 10.1002/2016GL068194
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2016
    detail.hit.zdb_id: 2021599-X
    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 6
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    Online Resource
    Massive isotopic effect in vacuum UV photodissociation of N 2 and implications for meteorite data
    Proceedings of the National Academy of Sciences ; 2014
    In:  Proceedings of the National Academy of Sciences Vol. 111, No. 41 ( 2014-10-14), p. 14704-14709
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 41 ( 2014-10-14), p. 14704-14709
    Abstract: Nitrogen isotopic distributions in the solar system extend across an enormous range, from −400‰, in the solar wind and Jovian atmosphere, to about 5,000‰ in organic matter in carbonaceous chondrites. Distributions such as these require complex processing of nitrogen reservoirs and extraordinary isotope effects. While theoretical models invoke ion-neutral exchange reactions outside the protoplanetary disk and photochemical self-shielding on the disk surface to explain the variations, there are no experiments to substantiate these models. Experimental results of N 2 photolysis at vacuum UV wavelengths in the presence of hydrogen are presented here, which show a wide range of enriched δ 15 N values from 648‰ to 13,412‰ in product NH 3 , depending upon photodissociation wavelength. The measured enrichment range in photodissociation of N 2 , plausibly explains the range of δ 15 N in extraterrestrial materials. This study suggests the importance of photochemical processing of the nitrogen reservoirs within the solar nebula.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1410440111
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Radar-Enabled Recovery of the Sutter’s Mill Meteorite, a Carbonaceous Chondrite Regolith Breccia
    American Association for the Advancement of Science (AAAS) ; 2012
    In:  Science Vol. 338, No. 6114 ( 2012-12-21), p. 1583-1587
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 338, No. 6114 ( 2012-12-21), p. 1583-1587
    Abstract: Doppler weather radar imaging enabled the rapid recovery of the Sutter’s Mill meteorite after a rare 4-kiloton of TNT–equivalent asteroid impact over the foothills of the Sierra Nevada in northern California. The recovered meteorites survived a record high-speed entry of 28.6 kilometers per second from an orbit close to that of Jupiter-family comets (Tisserand’s parameter = 2.8 ± 0.3). Sutter’s Mill is a regolith breccia composed of CM (Mighei)–type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits considerable diversity of mineralogy, petrography, and isotope and organic chemistry, resulting from a complex formation history of the parent body surface. That diversity is quickly masked by alteration once in the terrestrial environment but will need to be considered when samples returned by missions to C-class asteroids are interpreted.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.1227163
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2012
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
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  • 8
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    Online Resource
    New constraints of terrestrial and oceanic global gross primary productions from the triple oxygen isotopic composition of atmospheric CO2 and O2
    Springer Science and Business Media LLC ; 2023
    In:  Scientific Reports Vol. 13, No. 1 ( 2023-02-07)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2023-02-07)
    Abstract: Representations of the changing global carbon cycle under climatic and environmental perturbations require highly detailed accounting of all atmosphere and biosphere exchange. These fluxes remain unsatisfactory, as a consequence of only having data with limited spatiotemporal coverage and precision, which restrict accurate assessments. Through the nature of intimate coupling of global carbon and oxygen cycles via O 2 and CO 2 and their unique triple oxygen isotope compositions in the biosphere and atmosphere, greater insight is available. We report analysis of their isotopic compositions with the widest geographical and temporal coverage (123 new measurements for CO 2 ) and constrain, on an annual basis, the global CO 2 recycling time (1.5 ± 0.2 year) and gross primary productivities of terrestrial (~ 170–200 PgC/year) and oceanic (~ 90–120 PgC/year) biospheres. Observed inter-annual variations in CO 2 triple oxygen isotopic compositions were observed at a magnitude close to the largest contrast set by the terrestrial and oceanic biospheres. The seasonal cycles between the east and west Pacific Ocean were found to be drastically different. This intra-annual variability implies that the entire atmospheric CO 2 turnover time is not much longer than the tropospheric mixing time (less than ~ 5 months), verifying the derived recycling time. The new measurements, analyses, and incorporation of other global data sets allow development of an independent approach, providing a strong constraint to biogeochemical models.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-023-29389-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2615211-3
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  • 9
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    Online Resource
    Oxygen isotope anomaly in tropospheric CO2 and implications for CO2 residence time in the atmosphere and gross primary productivity
    Springer Science and Business Media LLC ; 2017
    In:  Scientific Reports Vol. 7, No. 1 ( 2017-10-13)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 7, No. 1 ( 2017-10-13)
    Abstract: The abundance variations of near surface atmospheric CO 2 isotopologues (primarily 16 O 12 C 16 O, 16 O 13 C 16 O, 17 O 12 C 16 O, and 18 O 12 C 16 O) represent an integrated signal from anthropogenic/biogeochemical processes, including fossil fuel burning, biospheric photosynthesis and respiration, hydrospheric isotope exchange with water, and stratospheric photochemistry. Oxygen isotopes, in particular, are affected by the carbon and water cycles. Being a useful tracer that directly probes governing processes in CO 2 biogeochemical cycles, Δ 17 O (=ln(1 + δ 17 O) − 0.516 × ln(1 + δ 18 O)) provides an alternative constraint on the strengths of the associated cycles involving CO 2 . Here, we analyze Δ 17 O data from four places (Taipei, Taiwan; South China Sea; La Jolla, United States; Jerusalem, Israel) in the northern hemisphere (with a total of 455 measurements) and find a rather narrow range (0.326 ± 0.005‰). A conservative estimate places a lower limit of 345 ± 70 PgC year −1 on the cycling flux between the terrestrial biosphere and atmosphere and infers a residence time of CO 2 of 1.9 ± 0.3 years (upper limit) in the atmosphere. A Monte Carlo simulation that takes various plant uptake scenarios into account yields a terrestrial gross primary productivity of 120 ± 30 PgC year −1 and soil invasion of 110 ± 30 PgC year −1 , providing a quantitative assessment utilizing the oxygen isotope anomaly for quantifying CO 2 cycling.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-017-12774-w
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 2615211-3
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  • 10
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    Online Resource
    On the strong and selective isotope effect in the UV excitation of N 2 with implications toward the nebula and Martian atmosphere
    Proceedings of the National Academy of Sciences ; 2011
    In:  Proceedings of the National Academy of Sciences Vol. 108, No. 15 ( 2011-04-12), p. 6020-6025
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 108, No. 15 ( 2011-04-12), p. 6020-6025
    Abstract: Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N 2 . The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1102767108
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2011
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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