Download or read book Nitrogen Cycling in Oxygen Deficient Zones written by Carolyn Buchwald and published by . This book was released on 2013 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stable isotopes, [delta]15N and [delta]18O, of nitrite and nitrate can be powerful tools used to interpret nitrogen cycling in the ocean. They are particularly useful in regions of the ocean where there are multiple sources and sinks of nitrogenous nutrients, which concentration profiles alone cannot distinguish. Examples of such regions are "oxygen deficient zones" (ODZ). They are of particular interest because they are also important hot spots of fixed N loss and production of N2O, a potent greenhouse gas. In order to interpret these isotope profiles, the isotope systematics of each process involved must be known so that we can distinguish the isotopic signature of each process. One of the important processes to consider here is nitrification, the process by which ammonium is oxidized nitrite and then to nitrate. This thesis describes numerous experiments using both cultures of nitrifying organisms as well as natural seawater samples to determine the oxygen isotope systematics of nitrification. These experimental incubations show that the accumulation of nitrite has a large effect on the resulting [delta]18ONO3. In experiments where nitrite does not accumulate, [delta]18ONO3 produced from nitrification is between -1 to l%o. These values will be applicable for the majority of the ocean, but the nitrite isotopic exchange will be important in the regions of the ocean where nitrite accumulates, such as the base of the euphotic zone and oxygen deficient zones. [delta]18ONO2 was developed as a unique tracer in this thesis because it undergoes abiotic equilibration with water [delta]18O at a predictable rate based on pH, temperature and salinity. This rate, its dependencies, and how the [delta]18ONO2 values can be used as not only biological source indicators but also indicators of age are described. This method was applied to samples from the primary nitrite maximum in the Arabian Sea, revealing that the dominant source and sinks of nitrite are ammonia oxidation and nitrite oxidation with an average age of 37 days. Finally, using the isotope systematics of nitrification as well as the properties of nitrite oxygen isotope exchange described in this thesis, the final chapter interprets multiisotope nitrate and nitrite profiles in the Costa Rica Upwelling Dome using a simple ID model. The nitrite isotopes showed that there were multiple sources of nitrite in the primary nitrite maximum including (1) decoupling of ammonia oxidation and nitrite oxidation, (2) nitrate reduction during assimilation and leakage of nitrite by phytoplankton. In the oxygen deficient zone and secondary nitrite maximum, there were equal contributions of nitrite removal from nitrite oxidation and nitrite reduction. This recycling of nitrite to nitrate through oxidation indicates that the percentage of reduced nitrate fully consumed to N2 gas is actually smaller than previous estimates. Overall, this thesis describes new nitrogen and oxygen isotopic tracers and uses them to elucidate the complicated nitrogen biogeochemistry in oxygen deficient zones.

Download or read book Stable Isotopes of Nitrite as a Tool for Understanding Nitrogen Cycling and Loss in Oxygen Deficient Zones written by Taylor Martin and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen (N), a key nutrient in the global ocean, has a complicated biogeochemical cycle. In the ocean, nitrogen is mainly found as nitrate (NO3-), but it also accumulates as nitrite (NO2-) within oxygen deficient zones (ODZs). Nitrite is a key intermediate in several processes that produce nitrous oxide (N2O), a potent greenhouse gas. Using natural abundance stable isotope measurements of NO3- and NO2- help to capture an integrated signal of the N cycle processes. My doctoral work aims to use stable isotopes of N and oxygen (O) in order to further our understanding of the pathways that produce and consume NO2-, which will help us better predict the global impacts of nitrogen cycling both at present and in the future. Many N cycle processes are microbially mediated and impart one or more unique isotope effects on its N substrates and products, and it is important to quantify these isotope effects in order to use numerical models to elucidate relative contributions of different N cycle processes. In Chapter 1, I use pure culture experiments to better constrain estimates of the N and O isotope effects of microbial nitrite reduction, a key step in the process of denitrification, which leads to loss of bioavailable N. I then use the values from this experiment, in conjunction with previous estimates of other N cycle process isotope effects, to model observed NO3- and NO2- data from the Arabian Sea (Chapter 2) and explore the necessity for oxygen-requiring processes within the ODZ. In Chapter 3, I expand upon the results from previous chapters by applying the results to a global 3D inverse model of the N cycle, which includes isotopic fractionation, in order to examine the NO2- production and consumption processes within marine ODZs. I also examine the sensitivity of NO3- and NO2- concentration and isotope profiles to controlling parameters of N cycle processes, such as oxygen thresholds and isotope effects, in order to examine the roles of individual processes in N loss, and their potential for future change.

Download or read book Nitrification written by Bess B. Ward and published by American Society for Microbiology Press. This book was released on 2011-03-25 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: A full review of the latest research findings on microbes involved in conventional aerobic nitrification, anaerobic ammonia oxidation, and related processes. • Examines the four principal groups of nitrifying microbes including conventional aerobic bacterial ammonia oxidizers, recently discovered aerobic archaeal ammonia oxidizers, anaerobic ammonia-oxidizing planctomycetes, and nitrite-oxidizing bacteria. • Provides current information on the ecology, phylogeny, biochemistry, molecular biology, and genomics of each group of microbes. • Discusses the latest industrial applications of nitrification and anammox processes, and explores the ecology of nitrification in marine, freshwater, soil, and wastewater environments.

Download or read book Nitrogen in the Marine Environment written by Edward J. Carpenter and published by Elsevier. This book was released on 2013-10-22 with total page 919 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen in the Marine Environment provides information pertinent to the many aspects of the nitrogen cycle. This book presents the advances in ocean productivity research, with emphasis on the role of microbes in nitrogen transformations with excursions to higher trophic levels. Organized into 24 chapters, this book begins with an overview of the abundance and distribution of the various forms of nitrogen in a number of estuaries. This text then provides a comparison of the nitrogen cycling of various ecosystems within the marine environment. Other chapters consider chemical distributions and methodology as an aid to those entering the field. This book discusses as well the enzymology of the initial steps of inorganic nitrogen assimilation. The final chapter deals with the philosophy and application of modeling as an investigative method in basic research on nitrogen dynamics in coastal and open-ocean marine environments. This book is a valuable resource for plant biochemists, microbiologists, aquatic ecologists, and bacteriologists.

Download or read book Methods of Seawater Analysis written by Klaus Grasshoff and published by John Wiley & Sons. This book was released on 2009-07-30 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the book first appeared in 1976, Methods of Seawater Analysis has found widespread acceptance as a reliable and detailed source of information. Its second extended and revised edition published in 1983 reflected the rapid pace of instrumental and methodological evolution in the preceding years. The development has lost nothing of its momentum, and many methods and procedures still suffering their teething troubles then have now matured into dependable tools for the analyst. This is especially evident for trace and ultra-trace analyses of organic and inorganic seawater constituents which have diversified considerably and now require more space for their description than before. Methods to determine volatile halocarbons, dimethyl sulphide, photosynthetic pigments and natural radioactive tracers have been added as well as applications of X-ray fluorescence spectroscopy and various electrochemical methods for trace metal analysis. Another method not previously described deals with the determination of the partial pressure of carbon dioxide as part of standardised procedures to describe the marine CO2 system.

Download or read book Nitrogen Cycling in Ecosystems of Latin America and the Caribbean written by G. Philip Robertson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: The large and rapidly expanding body ofliterature related to nitrogen cycling in both managed and native terrestrial ecosystems reflects the importance accorded to the behaviour of this vital and often limiting nutrient. Research at the organism, ecosystem and landscape levels commonly addresses questions concerning nitrogen acquisition, internal cycling and retention. Goals for this research include increased agricultural productivity and a better understanding of human impact on local, regional and global nitrogen cycles. Nitrogen cycle research in tropical regions has a long and distinguished history. Research on different aspects of nitrogen cycling in ecosystems of the tropics has been carried out in many regions. In relatively few instances has there, however, been a focus on the biogeochemical cycles at the ecosystem level. The meeting resulting in this volume was an attempt to bring together existing information on nitrogen cycling in ecosystems of Latin America and the Caribbean and discuss this in an ecosystem context.

Download or read book The microbial nitrogen cycle written by Bess B Ward and published by Frontiers Media SA. This book was released on 2015-01-17 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen is an essential element in biological systems, and one that often limits production in both aquatic and terrestrial systems. Due to its requirement in biological macromolecules, its acquisition and cycling have the potential to structure microbial communities, as well as to control productivity on the ecosystem scale. In addition, its versatile redox chemistry is the basis of complex biogeochemical transformations that control the inventory of fixed nitrogen, both in local environments and over geological time. Although many of the pathways in the microbial nitrogen cycle were described more than a century ago, additional fundamental pathways have been discovered only recently. These findings imply that we still have much to learn about the microbial nitrogen cycle, the organisms responsible for it, and their interactions in natural and human environments. Progress in nitrogen cycle research has been facilitated by recent rapid technological advances, especially in genomics and isotopic approaches. In this Research Topic, we reviewed the leading edge of nitrogen cycle research based on these approaches, as well as by exploring microbial processes in modern ecosystems.

Download or read book Recent Developments in Oxygen Minimum Zones Biogeochemistry written by Sudheesh Valliyodan and published by Frontiers Media SA. This book was released on 2023-12-18 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The European Nitrogen Assessment written by Mark A. Sutton and published by Cambridge University Press. This book was released on 2011-04-14 with total page 665 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting the first continental-scale assessment of reactive nitrogen in the environment, this book sets the related environmental problems in context by providing a multidisciplinary introduction to the nitrogen cycle processes. Issues of upscaling from farm plot and city to national and continental scales are addressed in detail with emphasis on opportunities for better management at local to global levels. The five key societal threats posed by reactive nitrogen are assessed, providing a framework for joined-up management of the nitrogen cycle in Europe, including the first cost-benefit analysis for different reactive nitrogen forms and future scenarios. Incorporating comprehensive maps, a handy technical synopsis and a summary for policy makers, this landmark volume is an essential reference for academic researchers across a wide range of disciplines, as well as stakeholders and policy makers. It is also a valuable tool in communicating the key environmental issues and future challenges to the wider public.

Download or read book The Chemical Evolution of the Atmosphere and Oceans written by Heinrich D. Holland and published by Princeton University Press. This book was released on 1984-07-21 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this first full-scale attempt to reconstruct the chemical evolution of the Earth's atmosphere and oceans, Heinrich Holland assembles data from a wide spectrum of fields to trace the history of the ocean-atmosphere system. A pioneer in an increasingly important area of scholarship, he presents a comprehensive treatment of knowledge on this subject, provides an extensive bibliography, and outlines problems and approaches for further research. The first four chapters deal with the turbulent first half billion years of Earth history. The next four chapters, devoted largely to the Earth from 3.9 to 0.6 b.y.b.p., demonstrate that changes in the atmosphere and oceans during this period were not dramatic. The last chapter of the book deals with the Phanerozoic Eon; although the isotopic composition of sulfur and strontium in seawater varied greatly during this period of Earth history, the chemical composition of seawater did not.

Download or read book Riverine Ecosystem Management written by Stefan Schmutz and published by Springer. This book was released on 2018-05-08 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book surveys the frontier of scientific river research and provides examples to guide management towards a sustainable future of riverine ecosystems. Principal structures and functions of the biogeosphere of rivers are explained; key threats are identified, and effective solutions for restoration and mitigation are provided. Rivers are among the most threatened ecosystems of the world. They increasingly suffer from pollution, water abstraction, river channelisation and damming. Fundamental knowledge of ecosystem structure and function is necessary to understand how human acitivities interfere with natural processes and which interventions are feasible to rectify this. Modern water legislation strives for sustainable water resource management and protection of important habitats and species. However, decision makers would benefit from more profound understanding of ecosystem degradation processes and of innovative methodologies and tools for efficient mitigation and restoration. The book provides best-practice examples of sustainable river management from on-site studies, European-wide analyses and case studies from other parts of the world. This book will be of interest to researchers in the field of aquatic ecology, river system functioning, conservation and restoration, to postgraduate students, to institutions involved in water management, and to water related industries.

Download or read book A New Instrument and Method for Nitrogen loss Studies in Oxygen Deficient Zones written by Andrew Reed and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Denitrification in the Nitrogen Cycle written by Han Golterman and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers presented at a Nato Advanced Re search Workshop entitled "DENITRIFICATION IN THE N-CYCLE," held in Braunschweig (W-Germany) from 24 to 27 Mai 1983. All expenses were provided by the North Atlantic Treaty Organization. The scientific programme was in the first instance planned by some members of the Eco-Science Panel under the stimulating organization of Dr. Oscar Ravera and the final programme was prepared in co-operation between Ravera and myself. However, even during the meeting important con tributions were added. The meeting was hosted by the Microbiologi cal Dept. of F.A.L., which also took care of the organizatory as pects. Nitrate is constantly lost from both terrestial and aquatic ecosystems, causing rnixed feelings between ecologists and agricul turists. While bacteriologically very rnuch is known, the ecology of the processes is still poorly understood, nor can it be evaluated what it rneans as an econornic loss for farrners and world food produc tion. Therefore this NATO Advanced Workshop was established to per mit a lirnited nurnber of scientists active in this field to corne to gether for a short while to address the following objectives: 1) To exchange ideas between scientists (bacteriologists and ecologists) and agronornists. 2) To assess the state of the art. 3) To discuss the difficulties of experimentation in the field. 4) To define future research. In order to accornplish these objectives, the workshopwas organ ized in three parts with the following thernes: 1) Bacteriological aspects of dentrification

Download or read book Global Implications of the Nitrogen Cycle written by Trelita de Sousa and published by Cambridge Scholars Publishing. This book was released on 2020-07-16 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen constitutes 78% of the Earth’s atmosphere and inevitably occupies a predominant role in marine and terrestrial nutrient biogeochemistry and the global climate. Callous human activities, like the excessive industrial nitrogen fixation and the incessant burning of fossil fuels, have caused a massive acceleration of the nitrogen cycle, which has, in turn, led to an increasing trend in eutrophication, smog formation, acid rain, and emission of nitrous oxide, which is a potent greenhouse gas, 300 times more powerful in warming the Earth’s atmosphere than carbon dioxide. This book comprehensively reviews the biotransformation of nitrogen, its ecological significance and the consequences of human interference. It will appeal to environmentalists, ecologists, marine biologists, and microbiologists worldwide, and will serve as a valuable guide to graduates, post-graduates, research scholars, scientists, and professors.

Download or read book Nitrogen Cycling in the Americas Natural and Anthropogenic Influences and Controls written by Luiz A. Martinelli and published by Springer Science & Business Media. This book was released on 2007-01-19 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in our understanding of the nitrogen cycle and the impact of anthropogenic activities on regional to global scales depend on the expansion of scientific studies to these fast-developing regions. This book presents a series of studies from across the Americas whose aim is to highlight key natural processes that control nitrogen cycling as well as discuss the main anthropogenic influences on the nitrogen cycle in both the tropical and temperate regions of the Americas.

Download or read book Nitrogen Cycling in Coastal Marine Environments written by T. Henry Blackburn and published by . This book was released on 1988-03-21 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen discharge to the coastal environment has been increasing, posing the threat of accelerated eutrofication. Considerable research has been conducted in recent years to examine the impact of the nitrogen loading in coastal ecosystems. Based on proceedings from a SCOPE symposium held at the University of Aarhus in July of 1985, this volume covers a variety of up-to-date developments in research on nitrogen cycling in coastal marine environments. Topics include the role of nitrogen in algal productivity, regeneration of nutrients in the water column and the sediments, and the flow of nitrogen in coastal ecosystems.

Download or read book Microbial Sulfur Metabolism written by Christiane Dahl and published by Springer Science & Business Media. This book was released on 2007-09-09 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: This revealing book details recent developments in the study of the relationship between sulfur and the microbial agents that affect its metabolism. In recent years, new methods have been applied to study the biochemistry and molecular biology of reactions of the global sulfur cycle, the microorganisms involved and their physiology, metabolism and ecology. These activities have uncovered fascinating new insights for the understanding of aerobic and anaerobic sulfur metabolism.