Themes and Sessions

17a: Geomicrobiology and Fossil Biosignatures
Convenor: Tanja Bosak
Keynote: Richard Pancost (Bristol University)
Orals: Mon AM
Posters: Tue PM
Molecular, isotopic and elemental signatures preserved in ancient sedimentary rocks are a significant source of information about past microbial ecosystems, metabolisms and environments. The interpretation of inorganic biosignatures depends on our knowledge about how biominerals in modern microbial ecosystems are formed and modified, and the value of molecular fossils critically depends on information about lipids and pigments in extant organisms. However, according to some estimates, less than 1% of bacteria and archaea can be grown and studied in pure culture. This session explores modern, and in particular cultivation independent, geochemical, microbiological and genomic techniques to explore microbial ecosystems and the traces that they may leave in the geological record.
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17b: Molecular Fossils and Compound Specific Isotopes
Convenors: Jochen Brocks, Roger Summons
Keynote: Gordon Love (University of California Riverside)
Orals: Tue AM
Posters: Wed AM
Molecular fossils (biomarkers) preserved in ancient sedimentary rocks are a significant source of information about past microbial ecosystems, metabolisms and environments. We invite submissions that apply biomarkers and compound specific C/H/N isotopes to explore ancient microbial ecosystems and metabolisms, environmental and climatic transitions and mass extinctions from the Precambrian to the present. We also welcome general contributions to biomarker research and organic geochemistry.
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17c: Fungi and Biogeochemical Cycles
Convenors: Steve Banwart, Philippe Van Cappellen, Jonathan Leake
Keynote: Anna Gorbushina
Orals: Tue AM, Tue PM
Posters: Wed AM
The central role of fungi in biogeochemical cycles includes the acquisition of mineral nutrients through mineral weathering, the sustenance of terrestrial ecosystems through recycling of N and P, and the turnover of soil organic carbon pools. These include effects on biogeochemical cycles that range from molecular scale fungal-mineral interactions to global biogeochemical cycles operating on geological timescales. A particular focus of this session is the symbiosis between plants and mycorrhiza fungi, and how it drives biogeochemical cycling in the rhizospere. As an example, in ectomycorrhizal (EM) symbioses the distal feeding roots of trees are invested in a mantle of fungal mycelium from which hyphal networks extend, supported by 20-30% of the net photosynthate of the trees. These networks intensively explore soil organic and mineral surfaces. In the boreal forest - the world’s largest vegetation system - virtually all nutrient uptake into the plants is through EM fungi, virtually all carbon release from living roots passes through them, and they typically contribute over half the carbon in soil solution. The biomass and activity of EM mycelia are enormous, with several hundreds of km of mycelia in 1 kg of forest soil. These networks penetrate deep into the soil (to the C horizon of the weathered regolith) and into cracks in rocks and minerals. It is now emerging that EM fungi and their microbial associates are far more directly involved in mass transfer of elements from minerals (e.g. P, N, K, Zn, Fe, Cu) than has been previously recognised. This session aims to provide an overview of fungal microbiology and its role in terrestrial ecology, and to present recent advances in understanding the specific impacts on soil geochemistry and element cycles. Contributions are invited on all aspects of fungal microbiology, physiology, ecology and impacts on geochemical cycles and earth systems, especially the impacts on weathering and the cycling of carbon and nutrient elements. Field, laboratory and modelling studies are equally relevant.
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17e: Calcification Processes and Microbes
Convenors: Maria Dittrich, Anna Gorbushina
Keynote: Wolfgang Krumbein (University of Oldenburg)
Orals: Mon PM
Posters: Tue PM
Carbonates are an important component of the rock record. Abiotic carbonate formation is well known, but several studies have shown that microorganisms are also key players in the formation of various carbonate minerals. This session focuses on ancient and modern examples from terrestrial and marine environments.
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17f: Linking Geochemical Tracers and Metabolic Pathways
Convenors: Boswell Wing, Aubrey Zerkle
Keynote: Valeriy Smirnov (University of Montana/Johns Hopkins University)
Orals: Wed AM
Posters: Tue AM
Several important problems in geology cannot be solved without including a geomicrobiological component (e.g. deep storage sites of CO₂ or nuclear wastes, oceanic crust hydrothermalism, low temperature serpentinization and hydrogen generation, sediments, generation of gas hydrates, anaerobic oxidation of methane, acid mine drainages, interpretation of ancient mineralization, etc). Approaches relying upon molecular biology are being developed and it is important to bridge their results with those of geochemical studies (e.g. stable isotopes) which allow for mass balance and fluxes determination. The purpose of this session is to gather studies coupling stable isotopes or other tracers with major metabolic pathways. The session will include studies showing laboratory calibrations of geochemical signatures induced by various microorganisms and biogeochemical interpretation of geochemical signatures due to specific microorganisms.
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17g: Functional Imaging of Microbial-Mineral Processes at the Molecular Scale
Convenors: Steve Bonneville, Karim Benzerara
Keynote: Rik Brydson (University of Leeds)
Orals: Thu PM
Posters: Tue AM
The identification, visualization and quantification of metabolic and geochemical processes between microbes and rocks has emerged over the last decades as an important field of research. Understanding microbe-mineral interfacial phenomena (i.e., dissolution, precipitation, secondary mineral formation…) is required in order to develop coherent macroscopic descriptions of a large array of microbial pathways in past and present environments. However, access to and sampling of materials at the scale of the respective interfacial processes is not trivial and it requires new technological approaches that have been developed and applied over the last few years to a variety of biogeochemical problems. This session aims at gathering scientists from a broad range of expertise in order to present the latest developments in microscopic and spectroscopic techniques (e.g., TEM/FIB, STXM, XPS, (Nano)-SIMS…) and proteins-/transcripts- tagging approaches (e.g., FISH, Raman…) applied to geo-microbiological laboratory or fields studies.
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17j: The Genomics of Geochemistry
Convenor: Greg Dick
Keynote: Kenneth Nealson (University of Southern California)
Orals: Thu AM
Posters: Wed AM
The availability of thousands of microbial genome sequences and a growing number of metagenomes is opening new views into how and why microorganisms drive elemental cycles. However, significant challenges remain in interpreting this data and translating it into geochemical implications. This session will highlight how genomics is transforming our understanding of microbial biogeochemistry, not only through sequencing of single organisms but also sequencing of mixed communities (metagenomics) and via methods such as transcriptomics and proteomics that address genome dynamics. Contributions that intimately link these emerging approaches to biogeochemical processes are encouraged.
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17k: Biogeochemical Processes and Cycles in Lakes, Sediments and Soils: New Approaches, Recent Findings, and Environmental Applications
Convenors: Céline Pallud, Anniet Laverman, Eric Viollier, Moritz Lehmann
Keynote: Bjorn Sundby (ISMER and McGill University)
Orals: Fri AM, Fri PM
Posters: Tue AM
Biogeochemical cycles of C, N, Fe, Mn and S are tightly interconnected in natural ecosystems. Such interconnections could have important effects on organic matter degradation in soils and aquatic sediments. Anaerobic degradation of organic matter has classically been studied in relation to denitrification, iron-, manganese- and sulfate-reduction. Recent work has shown a large range of alternative processes (e.g. anammox, denitrification coupled to Fe-, S- and CH₄- oxidation), that could potentially affect organic matter degradation rates. We invite presentations on all aspects of geochemical and isotopic tracers and their potential to provide insight into the cycling of bioimportant elements and the origin and fate of organic matter in soil and lake environments. We particularly encourage presentations focusing on links between the C, N, Fe and S cycles and the alternative modes of anaerobic microbial and geochemical pathways.
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07a: Oxygen over Earth History: The Great Oxidation Event, Oxidation of the Proterozoic Ocean-Atmosphere, and the Terminal Proterozoic Transition
Convenors: Galen Halverson, David Fike, Ariel Anbar
Keynotes: Jochen Brocks (ANU) , Simon Poulton (Newcastle University)
Orals: Fri AM, Fri PM
Posters: Mon AM
This session focuses on the application of geological, geochemical, and geobiological approaches to constrain the rises (and falls) of atmospheric oxygen and the evolution of ocean redox over Earth history. The session will be divided into three parts: (A) The Great Oxidation Event; (B) Oxidation of the Proterozoic Ocean-Atmosphere; and (C) the Terminal Proterozoic Transition. Specific approaches may include biomarkers, paleontology, mass-dependent or mass-independent S isotopes, light (e.g., C, N), or heavy stable isotopes (e.g., Fe, U), and trace metal abundances. Preference will be given to those submissions involving new analytical techniques or multi-disciplinary approaches. Modeling- and theoretically-based submissions are also encouraged.
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07g: Isotopic and Chemical Tracers in Archaeometry – New Approaches and Applications
Convenors: Jorge Spangenberg, Martine Regert
Keynote: Richard P. Evershed (University of Bristol)
Orals: Fri PM
Posters: Wed AM
Biogeochemistry and isotope geochemistry are fundamental tools used in the study of changes in past climates, environments and evolution of ancient societies. Recent results have encovered many new aspects of early socio-economic settings, including food availability, preparation and consumption, procurement strategies, palaeodiet, trading routes and migrations of populations. This session aims to bring together researchers from (organic and inorganic) chemistry, isotope geochemistry and archaeometry in order to describe new developments in the study of materials and artefacts recovered from archeological sites. Emphasis will be given to new analytical techniques and results of multidisciplinary case studies using geochemical, isotopic, mineralogical, botanical, and zoological methods. This session also aims to integrate contributions discussing the processes that affect the composition of archaeological remains and comparisons with modern reference materials.
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08c: Microbial Cycling of Iron Minerals
Convenors: Kristina Straub, Thilo Behrends
Keynote: Joel E. Kostka (Florida State University)
Orals: Tue AM, Tue PM
Posters: Wed AM
Microbially mediated redox and mineral transformations of ferric and ferrous iron play a pivotal role in the biogeochemical cycle of iron on Earth. This session is devoted to new findings on the contribution of prokaryotes to the global cycling of iron. Areas of special interest include I) rates, mechanisms and ecology of microbial iron oxidation or reduction, II) involvement of prokaryotes in changing the iron cycle during Earth’s history, III) importance of prokaryotes for the supply of iron as nutrient for eukaryotes and IV) microbially controlled or induced iron mineral formations.
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09c: Thermal Stability of Petroleum in the Earth's Subsurface
Convenors: Simon George, Yongchun Tang
Keynote: Xianming Xiao (Guangzhou Institute of Goechemistry)
Orals: Fri AM
Posters: Thu PM
Recent fluid-inclusion studies continue to show that petroleum exists in host rocks that have experienced prehnite-pumpellyite and amphibolite-grade metamorphism, which contradicts results from experimental studies on hydrocarbon thermal stability. Further, petroleum is known to exist in some very high temperature (>190°C) reservoirs, showing that the previous paradigm of oil destruction by 120-150°C is invalid. The start of oil-to-gas cracking likely depends on pressure, oil type, presence of catalysts and whether it is an open or closed system, but the precise controls remain poorly defined. This session is intended to bring together researchers working on this issue based on fluid inclusion, oil-cracking experiments, and natural gas exploration.
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10c: Biogeochemical Cycling: Linking the Biosphere to Mineral Deposits
Convenor: Gordon Southam
Keynote: James Saunders (Auburn University)
Orals: Thu AM
Posters: Mon PM
The near surface distribution and contribution of the biosphere to low temperature geochemical processes has important implications for the geochemistry, distribution and mineralogy of metals in the environment, with implications for the exploration & formation of ore deposits, and for the bioremediation of contaminated systems.
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13e: Molecular Soil Biogeochemistry
Convenors: Stefano Bernasconi, Michael W.I. Schmidt, Rienk Smittenberg
Keynote: Markus Kleber (Oregon State University)
Orals: Mon PM
Posters: Thu AM
Soil organic matter is the largest terrestrial organic carbon sink, a key driver of soil formation and fertility and an important archive of paleo-environmental conditions. This session focuses on soil organic matter characterization using molecular and/or isotopic techniques. Covered topics include organic matter dynamics under a changing climate, soil organic matter sequestration, fluxes and cycling of individual compounds, paleo-environmental and archaeological reconstructions.
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16b: Pathways and Regulation of Energy and Carbon Transfer in Deep-Sea Extreme Environments
Convenors: Stefan Sievert, Nadine Le Bris
Keynote: Costantino Vetriani (Rutgers University)
Orals: Tue AM
Posters: Thu PM
Some of the most extreme environments on Earth are found in the deep-ocean (hydrothermal vents, methane and hydrocarbon seeps, hypersaline lakes). They exhibit tremendous variability in a number of physico-chemical parameters, including temperature, pH, gas (H₂S, CO₂, CO, O₂) and heavy metal concentrations, and other potentially harmful chemicals. Yet they are among the most productive marine environments. Key processes sustaining deep-sea chemosynthetic communities have been highlighted (chemolithoautotrophy, symbiosis) but the wide range of biogeochemical pathways arising from the variety of redox conditions, and the complexity of energy transfer mechanisms from molecules to organisms remain to be described. Availability of chemical substrates and energy budgets, diversity of carbon fixation pathways, adaptability of symbioses, interactions between invertebrates and biogeochemical processes, and large-scale impact of these processes are major issues for which recent interdisciplinary studies and new analytical capabilities have allowed significant advances. These new insights provide a better understanding of the underlying mechanisms sustaining the high productivities of these ecosystems and their potential impact on global element cycling.
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16d: Exobiology: Are any Terrestrial Extremophiles Plausible Proxies for Hypothesized Microbial Life on Venus, Mars, or the Jovian Planets and their Satellites (E.g., Titan, Europa, Callisto, Enceladus)?
Convenors: Mary Voytek, David DesMarais
Keynote: David Des Marais (NASA Ames Research Center)
Orals: Mon PM
Posters: Thu PM
Investigations of contemporary microbial communities can guide our exploration of Earth's early biosphere as well as our search for life elsewhere in the solar system. Life as we know it requires liquid water. Evidence for the presence or past activity of water has been detected on several planetary bodies besides Earth. Accordingly our search for signs of past or present life elsewhere in the Solar System is enhanced by studies of the biogeochemistry, microbiology and biosignatures of extreme environments on Earth such as those in the subsurface, in hot springs and in frozen deposits. Recent Mars missions are providing additional clues to help focus such Earth-based studies. This session explores a broad range of topics including prebiotic chemical evolution, quantifying the habitability of environments, biogeochemical cycles, biosignatures, and the roles played by mineralization in biological evolution and the preservation of biosignatures.
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18c: Recent Developments in Microbial Techniques and Approaches to Geobiology
Convenors: Ann Pearson, Andreas Kappler
Keynote: Volker Thiel (University of Gottingen)
Orals: Thu PM
Posters: Wed AM
This session seeks contributions that apply novel molecular, genetic, microscopic, spectroscopic, and/or chemical approaches and techniques to explore questions of geobiology. Such approaches could include - but are not limited to - applications from metagenomics, novel imaging techniques, high-resolution analyses, spectroscopic methods, isotopic proxies (natural level and tracer experiments), and new classes of organic or inorganic biomarkers. Novel approaches to handling microbes and consortia in-situ and to improving culturing approaches also are welcomed.
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