Research Article| March 28, 2025 Surface Complexation and Reactivity of Ferrihydrite in Relation to its Surface and Mineral Structure, with Applications to Natural Systems Tjisse Hiemstra; Tjisse Hiemstra Wageningen University, Department of Soil Chemistry, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands [email protected] Search for other works by this author on: GSW Google Scholar Annette Hofmann; Annette Hofmann University Lille, CNRS, University Littoral Côte d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F 59000 Lille, France [email protected] Search for other works by this author on: GSW Google Scholar Juan C. Mendez; Juan C. Mendez Agronomic Research Center and Faculty of Agronomy, University of Costa Rica, San Pedro de Montes de Oca, San José, Costa Rica [email protected] Search for other works by this author on: GSW Google Scholar Yilina Bai Yilina Bai Wageningen University, Department of Soil Chemistry, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands [email protected] Search for other works by this author on: GSW Google Scholar Author and Article Information Tjisse Hiemstra Wageningen University, Department of Soil Chemistry, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands Annette Hofmann University Lille, CNRS, University Littoral Côte d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F 59000 Lille, France Juan C. Mendez Agronomic Research Center and Faculty of Agronomy, University of Costa Rica, San Pedro de Montes de Oca, San José, Costa Rica Yilina Bai Wageningen University, Department of Soil Chemistry, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands [email protected] [email protected] [email protected] [email protected] Publisher: Mineralogical Society of America First Online: 28 Mar 2025 Copyright © 2025 by the Mineralogical Society of AmericaMineralogical Society of America Reviews in Mineralogy and Geochemistry (2024) 91A (1): 175–227. https://doi.org/10.2138/rmg.2025.91A.06 Article history First Online: 28 Mar 2025 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Tjisse Hiemstra, Annette Hofmann, Juan C. Mendez, Yilina Bai; Surface Complexation and Reactivity of Ferrihydrite in Relation to its Surface and Mineral Structure, with Applications to Natural Systems. Reviews in Mineralogy and Geochemistry 2025;; 91A (1): 175–227. doi: https://doi.org/10.2138/rmg.2025.91A.06 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Ferrihydrite (Fh) is the most important iron (hydr)oxide from the perspective of regulating the bioavailability and mobility of ions in the natural environment. Its existence was already known in the nineteenth century. Van Bemmelen and Klobbie (1892) studied the composition of what they called in French "Oxyde Ferrique Humide Amorphe" (Van Bemmelen and Klobbie 1896), being different from "Hydroxyde Ferrique Cristallin". At about the same time (1895), X-rays were discovered by Wilhelm Conrad Röntgen, but their use for unraveling the structures of crystalline Fe (hydr)oxides and ferrihydrite was yet to come. In 1912, Max von Laue reported that... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Planets are formed inside disks around young stars. The gas, dust, and ice in these natal disks are the building materials of planets, and therefore their compositions fundamentally shape the final chemical compositions of planets. In this review, we summarize current observations of molecular lines in protoplanetary disks, from near-infrared to millimeter wavelengths. We discuss the basic types of chemical reactions in disks and the current development of chemical modeling. In particular, we highlight the progress made in understanding snowline locations, abundances of main carriers of carbon, oxygen, and nitrogen, and complex organic molecules in disks. Finally, we discuss efforts to trace planet formation history by combining the understanding of disk chemistry and planet formation processes.
Nearly 30 years after the discovery of the first exoplanet around a main sequence star, thousands of planets have now been confirmed. These discoveries have completely revolutionized our understanding of planetary systems, revealing types of planets that do not exist in our solar system but are common in extrasolar systems, and a wide range of system architectures. Our solar system is clearly not the default for planetary systems. The community is now moving beyond basic characterization of exoplanets (mass, radius, and orbits) towards a deeper characterization of their atmospheres and even surfaces. With improved observational capabilities there is potential to now probe the geology of rocky exoplanets; this raises the possibility of an analogous revolution in our understanding of rocky planet evolution. However, characterizing the geology or geological processes occurring on rocky exoplanets is a major challenge, even with next generation telescopes. This chapter reviews what we may be able to accomplish with these efforts in the near-term and long-term. In the near-term, the James Webb Space Telescope (JWST) is revealing which rocky planets lose versus retain their atmospheres. This chapter discusses the implications of such discoveries, including how even planets with no or minimal atmospheres can still provide constraints on surface geology and long-term geological evolution. Longer-term possibilities are then reviewed, including whether the hypothesis of climate stabilization by the carbonate-silicate cycle can be tested by next generation telescopes. New modeling strategies sweeping through ranges of possibly evolutionary scenarios will be needed to use the current and future observations to constrain rocky exoplanet geology and evolution.
It has become a common practice within the exoplanet field to say that "to know the star is to know the planet." The properties of the host star have a strong, direct influence on the interior and surface conditions of the orbiting planet and oftentimes measurements of planetary properties are made relative to the star's properties. Not only are observational measurements of the star necessary to determine even the most basic aspects of the planet (such as mass and radius), but the stellar environment influences how the planet evolves. Therefore, in this chapter, we begin by discussing the basics of stars, providing an overview of stellar formation, structure, photon and particle emissions, and evolution. Next, we go over the possible ways to determine the age of a star. We then outline how different kinds of stars are distributed within the Milky Way galaxy. Afterwards, we explain how to measure the composition of stars and the underlying math inherent to those observations, including caveats that are important when using the data for research applications. Finally, we explain the underlying physics and observations that enable stellar composition to be used as a proxy for planetary composition. In addition, given that this chapter focuses more on astronomy/astrophysics and uses a variety of important terms that may not be familiar to all readers, we have defined many terms either within the text or as a footnote for better interdisciplinary comprehension.
Planet Earth has evolved from an entirely anoxic planet with possibly a different tectonic regime to the oxygenated world with horizontal plate tectonics that we know today. For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time. A rich record of this geobiological evolution over most of Earth's history provides insights into the remote detectability of microbial life under a variety of planetary conditions. We leverage Earth's geobiological record with the aim of a) illustrating the current state of knowledge and key knowledge gaps about the early Earth as a reference point in exoplanet science research; b) compiling biotic and abiotic mechanisms that controlled the evolution of the atmosphere over time; and c) reviewing current constraints on the detectability of Earth's early biosphere with state-of-the-art telescope technology. We highlight that life may have originated on a planet with a different tectonic regime and strong hydrothermal activity, and under these conditions, biogenic CH_4 gas was perhaps the most detectable atmospheric biosignature. Oxygenic photosynthesis, which is responsible for essentially all O_2 gas in the modern atmosphere, appears to have emerged concurrently with the establishment of modern plate tectonics and the continental crust, but O_2 accumulation to modern levels only occurred late in Earth's history, perhaps tied to the rise of land plants. Nutrient limitation in anoxic oceans, promoted by hydrothermal Fe = fluxes, may have limited biological productivity and O_2 production. N_2O is an alternative biosignature that was perhaps significant on the redox-stratified Proterozoic Earth. We conclude that the detectability of atmospheric biosignatures on Earth was not only dependent on biological evolution but also strongly controlled by the evolving tectonic context.
We'll examine plate tectonics on Earth – its features and forces – and examine some concepts that may allow astronomers to ask useful questions regarding numeric models that putatively predict tectonic activity. But exo-planetologists should be aware that geologists are still attempting to understand: why does Earth operates as it does, and so much differently than its neighbors? Has it always operated this way and have other planets of the inner Solar System ever mimicked Earth's behavior in their past? These problems are unsolved, though some interesting speculative notions have emerged. Studies by Foley et al. et al. (2012) and Weller and Lenardic (2018), for example, attempt to distill the essential planetary properties that may influence if not dictate possible tectonic states, while Yin et al. (2016) propose a model of planetary tectonic surface features that appears remarkably precise. These studies yield some compelling expedients for analyses of planetary objects both within and outside our Solar System.
