Download or read book Geochemical Drivers of Organic Matter Decomposition in Arctic Tundra Soils written by and published by . This book was released on 2015 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change is warming tundra ecosystems in the Arctic, resulting in the decomposition of previously-frozen soil organic matter (SOM) and release of carbon (C) to the atmosphere; however, the processes that control SOM decomposition and C emissions remain highly uncertain. In this study, we evaluate geochemical factors that influence anaerobic production of carbon dioxide (CO2) and methane (CH4) in the active layers of four ice-wedge polygons. Surface and soil pore waters were collected during the annual thaw season over a two-year period in an area containing waterlogged, low-centered polygons and well-drained, high-centered polygons. We report spatial and seasonal patterns of dissolved gases in relation to the geochemical properties of Fe and organic C as determined using spectroscopic and chromatographic techniques. Iron was present as Fe(II) in soil solution near the permafrost boundary but enriched as Fe(III) in the middle of the active layer, similar to dissolved aromatic-C and organic acids. Dissolved CH4 increased relative to dissolved CO2 with depth and varied with soil moisture in the middle of the active layer in patterns that were positively correlated with the proportion of dissolved Fe(III) in transitional and low-centered polygon soils but negatively correlated in the drier flat- and high-centered polygons. These results suggest that microbial-mediated Fe oxidation and reduction influence respiration/fermentation of SOM and production of substrates (e.g., low-molecular-weight organic acids) for methanogenesis. As a result, we infer that geochemical differences induced by water saturation dictate microbial products of SOM decomposition, and Fe geochemistry is an important factor regulating methanogenesis in anoxic tundra soils.
Download or read book Pathways of Anaerobic Organic Matter Decomposition in Tundra Soils from Barrow Alaska written by and published by . This book was released on 2015 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic tundra soils store a large quantity of organic carbon that is susceptible to decomposition and release to the atmosphere as methane (CH4) and carbon dioxide (CO2) under a warming climate. Anaerobic processes that generate CH4 and CO2 remain unclear because previous studies have focused on aerobic decomposition pathways. To predict releases of CO2 and CH4 from tundra soils, it is necessary to identify pathways of soil organic matter decomposition under the anoxic conditions that are prevalent in Arctic ecosystems. Here molecular and spectroscopic techniques were used to monitor biological degradation of water-extractable organic carbon (WEOC) during anoxic incubation of tundra soils from a region of continuous permafrost in northern Alaska. Organic and mineral soils from the tundra active layer were incubated at -2, +4, or +8°C for up to 60 days to mimic the short-term thaw season. Results suggest that, under anoxic conditions, fermentation converted complex organic molecules into simple organic acids that were used in concomitant Fe-reduction and acetoclastic methanogenesis reactions. Nonaromatic compounds increased over time as WEOC increased. Organic acid metabolites initially accumulated in soils but were mostly depleted by day 60 because organic acids were consumed to produce Fe(II), CO2, and CH4. We conclude that fermentation of nonprotected organic matter facilitates methanogenesis and Fe reduction reactions, and that the proportion of organic acids consumed by methanogenesis increases relative to Fe reduction with increasing temperature. As a result, the decomposition pathways observed in this study are important to consider in numerical modeling of greenhouse gas production in the Arctic.
Download or read book Biogeochemical Cycles written by Katerina Dontsova and published by John Wiley & Sons. This book was released on 2020-04-14 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elements move through Earth's critical zone along interconnected pathways that are strongly influenced by fluctuations in water and energy. The biogeochemical cycling of elements is inextricably linked to changes in climate and ecological disturbances, both natural and man-made. Biogeochemical Cycles: Ecological Drivers and Environmental Impact examines the influences and effects of biogeochemical elemental cycles in different ecosystems in the critical zone. Volume highlights include: Impact of global change on the biogeochemical functioning of diverse ecosystems Biological drivers of soil, rock, and mineral weathering Natural elemental sources for improving sustainability of ecosystems Links between natural ecosystems and managed agricultural systems Non-carbon elemental cycles affected by climate change Subsystems particularly vulnerable to global change The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Book Review: http://www.elementsmagazine.org/archives/e16_6/e16_6_dep_bookreview.pdf
Download or read book Model Ecosystems in Extreme Environments written by and published by Academic Press. This book was released on 2019-05-29 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model Ecosystems in Extreme Environments, Second Edition examines ecosystems at the most extreme habitats and their interaction with the environment, providing a key element in our understanding of the role and function of microorganisms in nature. The book highlights current topics in the field, such as biodiversity and the structure of microbial communities in extreme environments, the effects of extreme environmental conditions on microbial ecosystems, and ecological and evolutionary interactions in extreme environments, among other topics. It will be a valuable text for faculty and students working with extremophiles and/or microbial ecology and researchers, including astrobiologists, biologists, evolutionary scientists, astronomers, geochemists and oceanographers. Explores, in detail, how microbial ecosystems thrive in extreme environments Highlights the relevance of extremophiles as model ecosystems to the study of microbial ecology Examines how extreme ecosystems can help our search for life on other planets
Download or read book Landscape and Environmental Effects on Organic Carbon in Tundra Soils Est Greenland written by Julia I. Bradley-Cook and published by . This book was released on 2015 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Arctic soils in the permafrost region store substantially more carbon than is contained in the atmosphere, and are undergoing rapid change associated with anthropogenic climate change. Soil decomposition is an important component of ecosystem carbon flux that creates a biological feedback with the potential to accelerate climate change. In this research, I investigated controls on soil carbon storage and respiration to evaluate sensitivities of soil carbon processes to key drivers of change, and their interactions, and tested metabolic theories that predict the thermal response of soil decomposition. To assess the controls of landscape age and climate on carbon storage, respiration potential and organic matter quality, I conducted long-term incubations of soils collected from four study areas across western Greenland. I found that soil carbon storage and organic matter quality varied with landscape age, but the nonlinear patterns across the gradient point to the importance of interactions with other controls on soil carbon. To test the carbon quality temperature hypothesis and measure temperature and moisture controls on microbial decomposition in shrub and graminoid soils, I conducted an incubation experiment on tundra mineral soils. In contrast to the theoretical predictions, I found that temperature sensitivity was significantly higher in graminoid soils than shrub soils. These results indicate that the large stocks of carbon in graminoid soils should be more susceptible to carbon mineralization in a warming Arctic than shrub soils. To evaluate landscape variation in carbon storage and respiration, I measured soil carbon stocks, in-situ soil respiration, and abiotic variables associated with functional vegetation types at nine study sites near Kangerlussuaq, Greenland. Results from this study provide further evidence that graminoid soils with high moisture content are "hot spots" for soil carbon accumulation and turnover within this tundra landscape. I linked estimates of soil carbon stocks to a high-resolution land cover classification map to create an inventory of tundra soil carbon stocks and estimate soil carbon losses under shrub expansion scenarios."
Download or read book Microbial Communities of Polar and Alpine Soils written by Laura Zucconi and published by Frontiers Media SA. This book was released on 2021-11-10 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Systems Biogeochemistry of Major Marine Biomes written by Aninda Mazumdar and published by John Wiley & Sons. This book was released on 2022-04-01 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: Systems Biogeochemistry of Major Marine Biomes A comprehensive system-level discussion of the geomicrobiology of the Earth’s oceans In Systems Biogeochemistry of Major Marine Biomes, a team of distinguished researchers delivers a systemic overview of biogeochemistry across a number of major physiographies of the global ocean: the waters and sediments overlying continental margins; the deep sub-surfaces; the Arctic and Antarctic oceans; and the physicochemical extremes such as the hypersaline and sulfidic marine zones, cold methane seeps and hydrothermal ecosystems. The book explores state-of-the-art advances in marine geomicrobiology and investigates the drivers of biogeochemical processes. It highlights the imperatives of the unique, fringe, and cryptic processes while studying the geological manifestations and ecological feedbacks of in situ microbial metabolisms. Taking a holistic approach toward the understanding of marine biogeochemical provinces, this book emphasizes the centrality of culture-dependent and culture-independent (meta-omics-based) microbiological information within a systems biogeochemistry framework. Perfect for researchers and scientists in the fields of geochemistry, geophysics, geomicrobiology, oceanography, and marine science, Systems Biogeochemistry of Major Marine Biomes will also earn a place in the libraries of policymakers and advanced graduate students seeking a one-stop reference on marine biogeochemistry.
Download or read book Size fractionation and Characterization of Cryoturbated Soil Organic Matter in Arctic Tundra Alaska written by Chunhao Xu and published by . This book was released on 2005 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Recent studies indicated a second layer of organic matter often accumulates in the lower active layer and upper permafrost in arctic tundra soils due to cryoturbation. The objective of this study is to characterize cryoturbated organic matter by the combination of physical size-fractionation approaches with modern analytical techniques. The results of elemental composition (C, N), stable isotope (13C, 15N), radiocarbon age (14C), and molecular fingerprints (Py-GC/MS) analysis indicated cryoturbated organic matters are little humified and highly bioavailable. SOM (soil organic matter) associated with fine sand size particles was considered to be the organic carbon pool most sensitive to the changing climate. Clay minerals stabilize less humifed organic matter than those in temperate and tropical soils. The bioavailable soluble organics extracted from cryoturbated organic matter were found to have significant long-term accumulated effects on carbon cycling. The similar molecular compositions between cryoturbated and surface organic matter suggest vegetation covers haven't changed since the early Holocene. Furthermore, the quality of SOM in moist acidic tundra is higher than that of wet nonacidic tundra. With the deepening active layer followed by thawing permafrost, cryoturbated organic matter could reenter the biogeochemical cycles in the Arctic, resulting in a positive feedback to climate change"--Leaf iii.
Download or read book Effects of Thermokarst Slumps on Ecosystem Carbon and Nitrogen in Upland Arctic Tundra written by Andres Felipe Baron Lopez and published by . This book was released on 2012 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results suggest that the undisturbed tundra soils contain large pools of buried organic matter that has been protected from decomposition by cold temperatures that inhibit microbial activity. RTS, as an abrupt spatial and temporal disturbance, have the capacity to rearrange massive quantities of surface soil and the C and N it contains, modifying the ecosystem soil and vegetation composition dynamics. RTS acts as a generator of new niches for plant colonization, exposes rich-nutrient mineral soil layers, mobilizes sediment to receiving waters, and modifies the local topography. RTS dynamics through time have the capacity to substantially alter the form and function in upland arctic tundra. Understanding the effects of RTS on ecosystem C and N dynamics offers a unique opportunity to establish links between climate change and the ecological impacts of changing disturbance regimes.
Download or read book Soil Organisms and Decomposition in Tundra written by Alfred John Holding and published by . This book was released on 1974 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biogeochemical Consequences of Shrub Expansion in Arctic Tundra written by Carly Anne Phillips and published by . This book was released on 2018 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of arctic ecosystems to global change will have critical effects on future climate. These ecosystems are experiencing the greatest rates of warming globally and store over half the world's soil carbon (C). Climate warming has already triggered the expansion of shrubs across tundra, raising questions about how shrubs will affect ecosystem C balance. Shrub functional traits like litter quality and mycorrhizal symbionts may accelerate the activity of soil microorganisms by increasing the rate of C inputs and changing the chemical composition of soil organic matter (SOM). In this dissertation, I investigated four mechanisms by which shrubs may affect the activity of soil microorganisms by comparing shrub and non-shrub soils using a combination of manipulative lab incubations and field experiments Specifically, I tested whether shrubs stimulate heterotrophic activity and C loss by 1) their litter inputs; 2) increasing the availability of soil nitrogen (N) and phosphorus (P); 3) promoting more labile SOM relative to non-shrub species; and 4) producing root systems with stronger stimulatory effects on microbial activity. I found evidence that shrubs stimulate soil heterotrophic respiration, but microbes responded uniformly to litter addition, regardless of soil origin. I found no evidence that shrubs alter microbial N and/or P limitation on soil microbes, but are limited by P.I also found that long-term warming reduced C and N stocks in sub-arctic tundra, but did not uniformly stimulate increases to microbial activity or C loss. My final dissertation chapter demonstrated that roots are the primary drivers of microbial activity in arctic soils, regardless of species identity. I also found evidence that shrub-induced changes to soil organic matter quality may increase microbial activity in organic soils. Further, I found that the relationship between soil C content and root growth was strongly horizon dependent, with increasing root growth leading to greater C content in organic soils and lower C content in mineral soils. Interestingly, shrub roots appear to ameliorate this negative relationship in the mineral horizon. Collectively, my results suggest that shrubs are fundamentally modifying C cycling, and are changing the chemical composition and spatial distribution of C stored in arctic ecosystems.
Download or read book Decomposition of organic matter in tundra written by O W (Bill) Heal and published by . This book was released on 1974 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soil Chemical Aspects of Plant Nutrition in Alpine Tundra at Eagle Summit Alaska written by Lee Stuart (Program director) and published by . This book was released on 1983 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organic Matter Decomposition Rates in Arctic Soils written by L. A. & J. C. F. Tedrow Douglas and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling Regulation of Decomposition and Related Root mycorrhizal Processes in Arctic Tundra Soils Final Report written by and published by . This book was released on 1992 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since this was the final year of this project principal activities were directed towards either collecting data needed to complete existing incomplete data sets or writing manuscripts. Data sets on Imnaviat Creek watershed basin are functionally complete and data finialized on the cellulose mineralizaiton and dust impact on soil organic carbon and phsophorus decomposition. Seven manuscripts were prepared, and are briefly outlined.
Download or read book Multi Scale Biogeochemical Processes in Soil Ecosystems written by Yu Yang and published by John Wiley & Sons. This book was released on 2022-03-23 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: MULTI-SCALE BIOGEOCHEMICAL PROCESSES IN SOIL ECOSYSTEMS Provides a state-of-the-art overview of research in soil biogeochemical processes and strategies for greenhouse gas mitigation under climate change Food security and soil health for the rapidly growing human population are threatened by increased temperature and drought, soil erosion and soil quality degradation, and other problems caused by human activities and a changing climate. Because greenhouse gas emission is the primary driver of climate change, a complete understanding of the cycles of carbon and major nutritional elements is critical for developing innovative strategies to sustain agricultural development and environmental conservation. Multi-Scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes is an up-to-date overview of recent research in soil biogeochemical processes and applications in ecosystem management. Organized into three parts, the text examines molecular-scale processes and critical reactions, presents ecosystem-scale studies of ecological hotspots, and discusses large-scale modeling and prediction of global biogeochemical cycles. Part of the Wiley - IUPAC Series on Biophysico-Chemical Processes in Environmental Systems, this authoritative volume: Provides readers with a systematic and interdisciplinary approach to sustainable agricultural development and management of soil ecosystems in a changing climate Features contributions from an international team of leading scientists Examines topics such as soil organic matter stabilization, soil biogeochemistry modeling, and soil responses to environmental changes Discusses strategies for mitigating greenhouse gas emission and improving soil health and ecosystems resilience Includes an introduction to working across scales to project soil biogeochemical responses to climatic change Multi-Scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes is essential reading for scientists, engineers, agronomists, chemists, biologists, academic researchers, consultants, and other professionals whose work involves the nutrient cycle, ecosystem management, and climate change.
Download or read book Soil Organic Matter Decomposition in Permafrost affected Soils and Sediments written by Josefine Walz and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
