Soil Carbon Cycling Constrained by Oxygen-dependent Enzyme Activity and Microbial Energetics PDF Download
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Author: Hannah Rose Naughton
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Soils contain up to three times as much dynamic carbon as the atmosphere, making them a critical carbon sink. Soil organic carbon (SOC) performs ecosystem services such as atmospheric carbon sequestration, retention of nutrients and water, promotion of good soil structure, and fueling microbial activity that leads to soil fertility. However, future climate and land use change endanger soil carbon stocks. An incomplete understanding of the mechanisms behind SOC degradation hinders our ability to model carbon cycling, particularly considering temporally and spatially heterogeneous soils. One key factor is the role oxygen availability plays in microbial energetics and enzyme activity, information critical to providing mechanistic predictions of SOC decay. My research explores how oxygen limitations and ensuing redox heterogeneity in soils control both the energetics of respiration, which ultimately controls greenhouse gas production of soils, and microbial access to organic substrates via oxidative enzyme depolymerization. I use both laboratory soil reactors and a floodplain field site as soil environments with spatially or temporally varying oxygen availability to test for enzymatic and thermodynamic limitations on SOC degradation and accompanying greenhouse gas production. Soil redox environment altered dissolved organic carbon (DOC) composition and chemistry over short times in the reactor setup and over short spatial scales in field soils. Oxygen-limited soils had more reduced organic C corresponding to lower thermodynamic favorability as a microbial substrate in anaerobic metabolisms. The reactors had a stark increase in relative abundance of lignin-like carbon going from aerobic to anaerobic environments, indicative of enzymatic limitations, but field soils indicated plant inputs counteract this often depth-related pattern. Aeration of soils resulted in equivalent respiration when normalized to SOC content, regardless of original microbial community or SOC composition, even in methanogenic soils lacking saprotrophic communities. This finding prompted exploration of the potential for abiotic, metal-catalyzed processes to depolymerize SOC in redox-heterogeneous floodplain soils. Ferrous iron better corresponded to phenol oxidation potential than any microbial or carbon-related predictors, highlighting the potential for rapid oxidative SOC depolymerization upon aeration of permanently or temporarily saturated soils containing reduced transition metals. Altogether, this work highlights the rapidity with which novel redox status of soils alters SOC composition, favorability as a microbial substrate, and potential for unexpected greenhouse gas release. Terrestrial carbon models are unlikely to accurately predict future stocks and fluxes of SOC if they do not account for the influence of heterogeneity of oxygen availability and ensuing effects on carbon lability.
Author: Hannah Rose Naughton
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Soils contain up to three times as much dynamic carbon as the atmosphere, making them a critical carbon sink. Soil organic carbon (SOC) performs ecosystem services such as atmospheric carbon sequestration, retention of nutrients and water, promotion of good soil structure, and fueling microbial activity that leads to soil fertility. However, future climate and land use change endanger soil carbon stocks. An incomplete understanding of the mechanisms behind SOC degradation hinders our ability to model carbon cycling, particularly considering temporally and spatially heterogeneous soils. One key factor is the role oxygen availability plays in microbial energetics and enzyme activity, information critical to providing mechanistic predictions of SOC decay. My research explores how oxygen limitations and ensuing redox heterogeneity in soils control both the energetics of respiration, which ultimately controls greenhouse gas production of soils, and microbial access to organic substrates via oxidative enzyme depolymerization. I use both laboratory soil reactors and a floodplain field site as soil environments with spatially or temporally varying oxygen availability to test for enzymatic and thermodynamic limitations on SOC degradation and accompanying greenhouse gas production. Soil redox environment altered dissolved organic carbon (DOC) composition and chemistry over short times in the reactor setup and over short spatial scales in field soils. Oxygen-limited soils had more reduced organic C corresponding to lower thermodynamic favorability as a microbial substrate in anaerobic metabolisms. The reactors had a stark increase in relative abundance of lignin-like carbon going from aerobic to anaerobic environments, indicative of enzymatic limitations, but field soils indicated plant inputs counteract this often depth-related pattern. Aeration of soils resulted in equivalent respiration when normalized to SOC content, regardless of original microbial community or SOC composition, even in methanogenic soils lacking saprotrophic communities. This finding prompted exploration of the potential for abiotic, metal-catalyzed processes to depolymerize SOC in redox-heterogeneous floodplain soils. Ferrous iron better corresponded to phenol oxidation potential than any microbial or carbon-related predictors, highlighting the potential for rapid oxidative SOC depolymerization upon aeration of permanently or temporarily saturated soils containing reduced transition metals. Altogether, this work highlights the rapidity with which novel redox status of soils alters SOC composition, favorability as a microbial substrate, and potential for unexpected greenhouse gas release. Terrestrial carbon models are unlikely to accurately predict future stocks and fluxes of SOC if they do not account for the influence of heterogeneity of oxygen availability and ensuing effects on carbon lability.
Author: Hui Li
Publisher: Frontiers Media SA
ISBN: 2832539114
Category : Science
Languages : en
Pages : 154
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Book Description
Author: Samuel Evan Barnett
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Soil dwelling microorganisms are essential components of numerous ecosystem processes and biogeochemical cycles. In particular, they are important actors in terrestrial carbon cycling, producing and turning over soil organic matter. Microbially mediated soil carbon cycling can be influenced by environmental conditions, with soil organic matter dynamics and carbon fate varying across biomes. Drastic alterations to soil habitat conditions brought about through anthropogenic changes to land-use (e.g. agriculture) can greatly influence these processes. However, we are limited in our understanding of how land-use regimes and other environmental conditions control microbially mediated soil carbon cycling. I took three approaches to explore this relationship. First, I examined how bacterial community assembly and composition differed across cropland, old-field, and forest soils. I found that homogeneous selection, whereby selection pressure causes bacterial communities to be more phylogenetically similar to each other than expected by random assembly from a metacommunity, was the dominant bacterial community assembly process across all three land-use types. However, I also found that land-use interacted with soil pH to drive the balance between stochastic and deterministic assembly processes. This result indicates a mechanism by which microbial communities may develop differently across land-use regimes. Second, I examined the overall organic matter turnover across land-use regimes and the identity of the bacterial taxa actively involved in this carbon processing. I found that the dynamics of organic matter turnover and the active bacterial populations involved were distinct across land-use regimes. From these patterns I developed a conceptual model explaining how initial microbial biomass, which is impacted by land-use, may control bacterial activities in organic matter turnover. Finally, I examined the genomic basis of bacterial life history strategies, specifically the copiotroph-oligotroph continuum. Life history strategy can explain both bacterial activity in soil carbon cycling and bacterial response to environmental change. I found that the abundance of transcription factor genes and genes encoding a secretion signal peptide were both genomic signatures of the copiotroph-oligotroph continuum. These signatures can be used to classify diverse microbes based on their life history strategy and may further explain the biological drivers of these strategies. I also developed a toolkit, MetaSIPSim, that simulates metagenomic DNA-stable isotope probing datasets. Such datasets can be used to improve metagenomic DNA-stable isotope probing methodologies and analyses, which in turn can be used to link microbial genes and genomes to in situ carbon cycling activity. Overall, this work advances our knowledge of, and ability to study the ecological and biological controls of bacterially mediated soil carbon cycling.
Author: Jack J. Middelburg
Publisher: Springer
ISBN: 3030108228
Category : Science
Languages : en
Pages : 118
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Book Description
This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed.
Author: William F. Martin
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110612410
Category : Science
Languages : en
Pages : 269
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Book Description
Mitochondria are sometimes called the powerhouses of eukaryotic cells, because mitochondria are the site of ATP synthesis in the cell. ATP is the universal energy currency, it provides the power that runs all other life processes. Humans need oxygen to survive because of ATP synthesis in mitochondria. The sugars from our diet are converted to carbon dioxide in mitochondria in a process that requires oxygen. Just like a fire needs oxygen to burn, our mitochondria need oxygen to make ATP. From textbooks and popular literature one can easily get the impression that all mitochondria require oxygen. But that is not the case. There are many groups of organismsm known that make ATP in mitochondria without the help of oxygen. They have preserved biochemical relicts from the early evolution of eukaryotic cells, which took place during times in Earth history when there was hardly any oxygen avaiable, certainly not enough to breathe. How the anaerobic forms of mitochondria work, in which organisms they occur, and how the eukaryotic anaerobes that possess them fit into the larger picture of rising atmospheric oxygen during Earth history are the topic of this book.
Author: Josep M. Gasol
Publisher: John Wiley & Sons
ISBN: 1119107202
Category : Science
Languages : en
Pages : 663
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Book Description
The newly revised and updated third edition of the bestselling book on microbial ecology in the oceans The third edition of Microbial Ecology of the Oceans features new topics, as well as different approaches to subjects dealt with in previous editions. The book starts out with a general introduction to the changes in the field, as well as looking at the prospects for the coming years. Chapters cover ecology, diversity, and function of microbes, and of microbial genes in the ocean. The biology and ecology of some model organisms, and how we can model the whole of the marine microbes, are dealt with, and some of the trophic roles that have changed in the last years are discussed. Finally, the role of microbes in the oceanic P cycle are presented. Microbial Ecology of the Oceans, Third Edition offers chapters on The Evolution of Microbial Ecology of the Ocean; Marine Microbial Diversity as Seen by High Throughput Sequencing; Ecological Significance of Microbial Trophic Mixing in the Oligotrophic Ocean; Metatranscritomics and Metaproteomics; Advances in Microbial Ecology from Model Marine Bacteria; Marine Microbes and Nonliving Organic Matter; Microbial Ecology and Biogeochemistry of Oxygen-Deficient Water Columns; The Ocean’s Microscale; Ecological Genomics of Marine Viruses; Microbial Physiological Ecology of The Marine Phosphorus Cycle; Phytoplankton Functional Types; and more. A new and updated edition of a key book in aquatic microbial ecology Includes widely used methodological approaches Fully describes the structure of the microbial ecosystem, discussing in particular the sources of carbon for microbial growth Offers theoretical interpretations of subtropical plankton biogeography Microbial Ecology of the Oceans is an ideal text for advanced undergraduates, beginning graduate students, and colleagues from other fields wishing to learn about microbes and the processes they mediate in marine systems.
Author: Beth N. Orcutt
Publisher: Cambridge University Press
ISBN: 1108477496
Category : Nature
Languages : en
Pages : 687
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Book Description
A comprehensive guide to carbon inside Earth - its quantities, movements, forms, origins, changes over time and impact on planetary processes. This title is also available as Open Access on Cambridge Core.
Author: John W. Day
Publisher: Springer
ISBN: 9401787336
Category : Technology & Engineering
Languages : en
Pages : 203
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Book Description
Human impacts and emerging mega-trends such as climate change and energy scarcity will impact natural resource management in this century. This is especially true for deltas because of their ecological and economic importance and their sensitivity to climate change. The Mississippi delta is one of the largest in the world and has been strongly impacted by human activities. Currently there is an ambitious plan for restoration of the delta. This book, by a renown group of delta experts, provides an overview of the challenges facing the delta and charts - a way forward to sustainable management.
Author: Michael John Singer
Publisher: MacMillan Publishing Company
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 538
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Book Description
Now in paperback, this book provides a fresh look at soil science. The goal is to help readers understand the parts that contribute to the whole soil individual and then appreciate how those parts function together. It begins by assembling the parts (solid, liquid and gas phases) of a soil, followed by explaining the interactions among the parts. Subsequently, genesis, classification, and interpretation of soil properties are explained. The " building the pedon" concept introduced in the first edition is continued in this latest edition. This edition also has a " western" perspective that emphasizes water management. For individuals whose careers involve environmental or land use management such as soil scientists, soil conservationists, forest soil scientists, environmental scientists, or geologists.
Author: Craig E. Manning
Publisher: John Wiley & Sons
ISBN: 1119508231
Category : Science
Languages : en
Pages : 373
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Book Description
Carbon in Earth's fluid envelopes - the atmosphere, biosphere, and hydrosphere, plays a fundamental role in our planet's climate system and a central role in biology, the environment, and the economy of earth system. The source and original quantity of carbon in our planet is uncertain, as are the identities and relative importance of early chemical processes associated with planetary differentiation. Numerous lines of evidence point to the early and continuing exchange of substantial carbon between Earth's surface and its interior, including diamonds, carbon-rich mantle-derived magmas, carbonate rocks in subduction zones and springs carrying deeply sourced carbon-bearing gases. Thus, there is little doubt that a substantial amount of carbon resides in our planet's interior. Yet, while we know it must be present, carbon's forms, transformations and movements at conditions relevant to the interiors of Earth and other planets remain uncertain and untapped. Volume highlights include: - Reviews key, general topics, such as carbonate minerals, the deep carbon cycle, and carbon in magmas or fluids - Describes new results at the frontiers of the field with presenting results on carbon in minerals, melts, and fluids at extreme conditions of planetary interiors - Brings together emerging insights into carbon's forms, transformations and movements through study of the dynamics, structure, stability and reactivity of carbon-based natural materials - Reviews emerging new insights into the properties of allied substances that carry carbon, into the rates of chemical and physical transformations, and into the complex interactions between moving fluids, magmas, and rocks to the interiors of Earth and other planets - Spans the various chemical redox states of carbon, from reduced hydrocarbons to zero-valent diamond and graphite to oxidized CO2 and carbonates - Captures and synthesizes the exciting results of recent, focused efforts in an emerging scientific discipline - Reports advances over the last decade that have led to a major leap forward in our understanding of carbon science - Compiles the range of methods that can be tapped tap from the deep carbon community, which includes experimentalists, first principles theorists, thermodynamic modelers and geodynamicists - Represents a reference point for future deep carbon science research Carbon in Planetary Interiors will be a valuable resource for researchers and students who study the Earth's interior. The topics of this volume are interdisciplinary, and therefore will be useful to professionals from a wide variety of fields in the Earth Sciences, such as mineral physics, petrology, geochemistry, experimentalists, first principles theorists, thermodynamics, material science, chemistry, geophysics and geodynamics.
