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8. Multiple episodes of extensive marine anoxia linked to global warming and continental weathering following the latest Permian mass extinction.

Author

Zhang, Feifei, Romaniello, Stephen J, Algeo, Thomas J, Lau, Kimberly V, Clapham, Matthew E, Richoz, Sylvain, Herrmann, Achim D, Smith, Harrison, Horacek, Micha, and Anbar, Ariel D

Abstract

Explaining the ~5-million-year delay in marine biotic recovery following the latest Permian mass extinction, the largest biotic crisis of the Phanerozoic, is a fundamental challenge for both geological and biological sciences. Ocean redox perturbations may have played a critical role in this delayed recovery. However, the lack of quantitative constraints on the details of Early Triassic oceanic anoxia (for example, time, duration, and extent) leaves the links between oceanic conditions and the delayed biotic recovery ambiguous. We report high-resolution U-isotope (δ238U) data from carbonates of the uppermost Permian to lowermost Middle Triassic Zal section (Iran) to characterize the timing and global extent of ocean redox variation during the Early Triassic. Our δ238U record reveals multiple negative shifts during the Early Triassic. Isotope mass-balance modeling suggests that the global area of anoxic seafloor expanded substantially in the Early Triassic, peaking during the latest Permian to mid-Griesbachian, the late Griesbachian to mid-Dienerian, the Smithian-Spathian transition, and the Early/Middle Triassic transition. Comparisons of the U-, C-, and Sr-isotope records with a modeled seawater PO43- concentration curve for the Early Triassic suggest that elevated marine productivity and enhanced oceanic stratification were likely the immediate causes of expanded oceanic anoxia. The patterns of redox variation documented by the U-isotope record show a good first-order correspondence to peaks in ammonoid extinctions during the Early Triassic. Our results indicate that multiple oscillations in oceanic anoxia modulated the recovery of marine ecosystems following the latest Permian mass extinction.

Published
2018

24. Microbial Catalysis for CO2Sequestration: A Geobiological Approach

Author

Van Den Berghe, Martin, primary, Walworth, Nathan G., additional, Dalvie, Neil C., additional, Dupont, Chris L., additional, Springer, Michael, additional, Andrews, M. Grace, additional, Romaniello, Stephen J., additional, Hutchins, David A., additional, Montserrat, Francesc, additional, Silver, Pamela A., additional, and Nealson, Kenneth H., additional

Published
2023
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29. Responses of globally important phytoplankton groups to olivine dissolution products and implications for carbon dioxide removal via ocean alkalinity enhancement

Author

Hutchins, David, Fu, Fei-Xue, Yang, Shun-Chung, John, Seth, Romaniello, Stephen, Andrews, Grace, and Walworth, Nathan

Abstract

Anthropogenic greenhouse gas emissions are leading to global temperature increases, ocean acidification, and significant ecosystem impacts. Given current emissions trajectories, the IPCC calls for both the rapid abatement of CO2emissions and development of carbon dioxide removal (CDR) strategies that can address legacy emissions and difficult to abate emissions sources. These CDR methods must efficiently and safely sequester gigatons of atmospheric CO2. Coastal Enhanced Weathering (CEW) via the addition of the common mineral olivine to coastal waters is one promising approach to enhance ocean alkalinity for large-scale CDR. As olivine weathers, it releases several biologically active dissolution products, including alkalinity, trace metals, and the nutrient silicate. Released trace metals can serve as micronutrients but may also be toxic at high concentrations to marine biota including phytoplankton that lie at the base of marine food webs. We grew several globally important phytoplankton functional groups under elevated concentrations of olivine dissolution products using a synthetic olivine leachate (OL) based on olivine elemental composition, and monitored their physiological and biogeochemical responses. This allowed us to determine physiological impacts and thresholds at elevated olivine leachate concentrations, in addition to individual effects of specific constituents. We found both positive and neutral responses but no evident toxic effects for two silicifying diatoms, a calcifying coccolithophore, and three cyanobacteria. In both single and competitive co-cultures, silicifiers and calcifiers benefited from olivine dissolution products like iron and silicate or enhanced alkalinity, respectively. The non-N2-fixing picocyanobacterium could use synthetic olivine-derived iron for growth, while N2-fixing cyanobacteria could not. However, other trace metals like nickel and cobalt supported cyanobacterial growth across both groups. Growth benefits to particular phytoplankton groupsin situwill depend on species-specific responses and ambient concentrations of other required nutrients. Results suggest olivine dissolution products appear unlikely to cause negative effects for marine phytoplankton, even at high concentrations, and may support growth of particular taxa under some conditions. Future studies can shed light on long-term evolutionary responses to olivine exposure, and on the potential effects that marine microbes may in turn have on olivine dissolution rates and regional biogeochemistry.

Published
2023

37. Major Early-Middle Devonian oceanic oxygenation linked to early land plant evolution detected using high-resolution U isotopes of marine limestones

Author

Elrick, Maya, primary, Gilleaudeau, Geoffrey J., additional, Romaniello, Stephen J., additional, Algeo, Thomas J., additional, Morford, Jennifer L., additional, Sabbatino, Monia, additional, Goepfert, Tyler J., additional, Cleal, Christopher, additional, Cascales-Miñana, Borja, additional, and Chernyavskiy, Pavel, additional

Published
2022
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43. Reconciling evidence of oxidative weathering and atmospheric anoxia on Archean Earth

Author

Johnson, Aleisha C., Ostrander, Chadlin, Romaniello, Stephen J., Reinhard, Christopher T., Greaney, Allison T., Lyons, Timothy W., Anbar, Ariel D., Johnson, Aleisha C., Ostrander, Chadlin, Romaniello, Stephen J., Reinhard, Christopher T., Greaney, Allison T., Lyons, Timothy W., and Anbar, Ariel D.

Abstract

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, A. C., Ostrander, C. M., Romaniello, S. J., Reinhard, C. T., Greaney, A. T., Lyons, T. W., & Anbar, A. D. Reconciling evidence of oxidative weathering and atmospheric anoxia on Archean Earth. Science Advances, 7(40), (2021): eabj0108, https://doi.org/10.1126/sciadv.abj0108., Evidence continues to emerge for the production and low-level accumulation of molecular oxygen (O2) at Earth’s surface before the Great Oxidation Event. Quantifying this early O2 has proven difficult. Here, we use the distribution and isotopic composition of molybdenum in the ancient sedimentary record to quantify Archean Mo cycling, which allows us to calculate lower limits for atmospheric O2 partial pressures (PO2) and O2 production fluxes during the Archean. We consider two end-member scenarios. First, if O2 was evenly distributed throughout the atmosphere, then PO2 > 10–6.9 present atmospheric level was required for large periods of time during the Archean eon. Alternatively, if O2 accumulation was instead spatially restricted (e.g., occurring only near the sites of O2 production), then O2 production fluxes >0.01 Tmol O2/year were required. Archean O2 levels were vanishingly low according to our calculations but substantially above those predicted for an abiotic Earth system., We would like to thank our funding sources, including FESD “Dynamics of Earth System Oxygenation” (NSF EAR 1338810 to A.D.A.), NASA Earth and Space Science Fellowship awarded to A.C.J. (80NSSC17K0498), NSF EAR PF to A.C.J. (1952809), and WHOI Postdoctoral Fellowship to C.M.O. C.T.R. acknowledges support from the NASA Astrobiology Institute. We also acknowledge support from the Metal Utilization and Selection across Eons (MUSE) Interdisciplinary Consortium for Astrobiology Research, sponsored by the National Aeronautics and Space Administration Science Mission Directorate (19-ICAR19_2-0007).

Published
2021

45. Marine mineral-catalyzed NO and N2O formation on the anoxic early Earth

Author

Buessecker, Steffen, Ely, Tucker, Hu, Renyu, Cadillo-Quiroz, Hinsby, Imanaka, Hiroshi, and Romaniello, Stephen

Subjects
bepress|Physical Sciences and Mathematics, bepress|Physical Sciences and Mathematics|Earth Sciences, bepress|Physical Sciences and Mathematics|Earth Sciences|Geochemistry, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geochemistry, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, equipment and supplies, EarthArXiv|Physical Sciences and Mathematics
Abstract

Microbial metabolisms were limited by available terminal electron acceptors in the anoxic environment of the early Archean. However, iron mineral phases in Fe2+-rich (ferruginous) oceans could have catalyzed reactions with abiotically fixed nitrogen leading to the formation of nitrous oxide (N2O), a potentially favorable terminal electron acceptor. We experimentally simulated anoxic surface-catalyzed reduction of nitrite and nitrate via green rust and magnetite. Besides N2O, we detected and quantified the formation of substantial amounts of nitric oxide (NO). While N2O escaped into the gas phase (63% of nitrite-nitrogen, with green rust as catalyst), NO remained associated with precipitates (7% of nitrite-nitrogen). Using diffusion and photochemical modeling, we show that marine N2O emissions could have sustained atmospheric N2O pools of 1-7 ppb. Although this concentration was insufficient to cause significant warming, the seawater enriched in N2O and NO could have critically affected early benthic life by providing the opportunity to conserve energy.

Published
2020

46. Uranium isotopes in marine carbonates as a global ocean paleoredox proxy:A critical review

Author

Zhang, Feifei, Lenton, Timothy M., del Rey, Álvaro, Romaniello, Stephen J., Chen, Xinming, Planavsky, Noah J., Clarkson, Matthew O., Dahl, Tais W., Lau, Kimberly V., Wang, Wenqian, Li, Ziheng, Zhao, Mingyu, Isson, Terry, Algeo, Thomas J., Anbar, Ariel D., Zhang, Feifei, Lenton, Timothy M., del Rey, Álvaro, Romaniello, Stephen J., Chen, Xinming, Planavsky, Noah J., Clarkson, Matthew O., Dahl, Tais W., Lau, Kimberly V., Wang, Wenqian, Li, Ziheng, Zhao, Mingyu, Isson, Terry, Algeo, Thomas J., and Anbar, Ariel D.

Abstract

The protracted oxygenation of the ocean-atmosphere system is one of the most fundamental changes to the Earth system through its history. The uranium isotopic composition (238U/235U, denoted as δ238U) of marine carbonates has been developed as a proxy to quantitatively track the timing, duration, and extent of global marine redox chemistry changes. This proxy has been applied to many critical evolutionary intervals in the last decade, significantly advancing our understanding of how life on Earth and its environment have co-evolved through geological history. Successful application of the uranium isotope paleoredox proxy requires a thorough understanding of the marine uranium budget, the processes by which seawater U-isotope signatures are recorded in marine carbonates, and the potential for alteration of these primary signatures by syn- and post-depositional diagenetic processes. Here, we provide a critical review of the U isotope proxy in marine carbonates with a focus on the current problems and areas where future work is needed to further develop this proxy. We also use a recently developed global C-P-U cycle model to illustrate that when the carbon cycle is perturbed by volcanic carbon injections, the ensuing transient relationship between seafloor anoxic area and δ238U can be complex and sometimes counter-intuitive.

Published
2020

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