Download or read book N and O Isotope Ratios of NO3 as a Tracer for Nitrogen Cycling and Water Mass Distribution written by Nadine Lehmann and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen plays a central role in marine biogeochemistry. Its distribution, chemical speciation and ratio relative to other nutrients governs the presence and abundance of microbial communities, and of large scale ocean production. In this respect, my thesis examines how biochemical and physical processes regulate the distribution of different nitrogen (N) species and their transformation in various marine environments by evaluating the spatial distribution of nitrogen and oxygen isotopes of nitrate (NO3-), in combination with a varying set of complementary biogeochemical tracers. Chapter 2 examines the isotopic composition of NO3- and total dissolved inorganic carbon (DIC) to elucidate the hydrography of the Western Equatorial Pacific (WEP) and biogeochemical evolution of water masses that contribute to the Equatorial Undercurrent (EUC). Based on isotope data and water mass mixing estimates, I highlight the different biogeochemical histories of nutrients feeding the northern and southern WEP, and provide support for the theory of a predominantly Southern Ocean source of NO3- to the EUC. Chapter 3 focuses on Baffin Bay, which represents a major link between the high Arctic and the northwestern Atlantic, owing to its effect on the salt and nutrient budgets of the adjacent Labrador Sea and the wider Atlantic Ocean. I combine NO3- isotope ratios with nitrous oxide (N2O) isotope measurements to identify the origin of the pronounced N-deficit and N2O supersaturation prevalent in deep Baffin Bay. The set of isotopic tracers used in this study allows the identification of different, yet complementary, N transformation processes. NO3- isotopes reflect substantial in situ remineralization of organic matter originating from surface productivity fueled by Pacific-derived nutrients, whereas N2O isotopomer abundances point to sedimentary denitrification as a potential source of the N-deficiency observed in the deep basin. In chapter 4, I use NO3- isotope ratios measured in the Canada Basin and in the Baffin Bay together with hydrographic data and nutrient ratios as a baseline to evaluate the distribution of Pacific- and Atlantic-derived water masses throughout the Arctic Archipelago. With this work, I highlight the importance and applicability of dual isotope measurements as water mass tracers and provide insights into individual processes within the N cycle.
Download or read book Nitrate nitrogen and Nitrate oxygen Isotope Ratios for Identification of Nitrate Sources and Dominant Nitrogen Cycle Processes in a Tile drained Dryland Agricultural Field written by Christopher Joshua Kelley and published by . This book was released on 2011 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotope Tracers in Catchment Hydrology written by C. Kendall and published by Elsevier. This book was released on 2012-12-02 with total page 870 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents a new "earth systems" approach to catchments that encompasses the physical and biogeochemical interactions that control the hydrology and biogeochemistry of the system. The text provides a comprehensive treatment of the fundamentals of catchment hydrology, principles of isotope geochemistry, and the isotope variability in the hydrologic cycle -- but the main focus of the book is on case studies in isotope hydrology and isotope geochemistry that explore the applications of isotope techniques for investigating modern environmental problems. Isotope Tracers in Catchment Hydrology is the first synthesis of physical hydrology and isotope geochemistry with catchment focus, and is a valuable reference for professionals and students alike in the fields of hydrology, hydrochemistry, and environmental science. This important interdisciplinary text provides extensive guidelines for the application of isotope techniques for all investigatores facing the challenge of protecting precious water, soil, and ecological resources from the ever-increasing problems associated with population growth and environmental change, including those from urban development and agricultural land uses.
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 Environmental Tracers in Subsurface Hydrology written by Peter G. Cook and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental Tracers in Subsurface Hydrology synthesizes the research of specialists into a comprehensive review of the application of environmental tracers to the study of soil water and groundwater flow. The book includes chapters which cover ionic tracers, noble gases, chlorofluorocarbons, tritium, chlorine-36, oxygen-18, deuterium, and isotopes of carbon, strontium, sulphur and nitrogen. Applications of the tracers include the estimation of vertical and horizontal groundwater velocities, groundwater recharge rates, inter-aquifer leakage and mixing processes, chemical processes and palaeohydrology. Practicing hydrologists, soil physicists and hydrology professors and students will find the book to be a valuable support in their work.
Download or read book Nitrogen Isotope Techniques written by and published by Elsevier. This book was released on 2012-12-02 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first laboratory manual to bring together basic procedures for measurement of stable and radioactive isotopes of nitrogen, with specific applications to plant, soil, and aquatic biology. This bench-top reference gives practical coverage of mass and emission spectrometry, nitrogen fixation, nitrification, and identification, organic nitrogen, and the radioactive isotope 13N. Methods are described so that researchers can adapt them, without the aid of outside references, to virtually any task they may encounter in investigations of nitrogen transformation processes. - Serves as a practical guide for nitrogen isotope techniques - Features studies of nitrogen transformations in terrestrial and aquatic systems - Includes basic measurement techniques plus specific applications for stable and radioactive nitrogen isotopes - Presents detailed protocols, overviews, and key references - Includes fifty figures and sixteen tables - Hands-on reference for both students and researchers
Download or read book Use of Natural Abundance Stable Nitrogen Isotope Ratio Measurements to Investigate Mechanisms of Nitrogen Loss in the Hidden Valley Wildlife Area Ponds Riverside CA written by Marlene Ann Braun and published by . This book was released on 1991 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Determining Sources of Nitrate in the Semi arid Rio Grande Using Nitrogen and Oxygen Isotopes written by Diego Alberto Sanchez Hernandez and published by . This book was released on 2017 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Rio Grande, a semi-arid river in the American Southwest, is a major source of surface water for agriculture and drinking supplies in New Mexico and Texas. In addition to increasing salinity, considerable increases of NO3− [nitrate] have been observed in the semi-arid portion of the Rio Grande. It is possible that elevated water salinity inhibits denitrification on irrigated fields and, thus, fails to mediate excess nutrient load from anthropogenic activities. Therefore, two major goals of this project were to 1) characterize and quantify major NO3− sources, and 2) assess whether elevated water salinity affects microbial denitrification. In fall 2014 and summer 2015, surface water, irrigation drains, urban runoff, and municipal waste effluents were sampled between Elephant Butte, New Mexico and Tornillo, Texas for stable isotope analysis. Highest NO3− concentrations were observed in waste effluents and nearby agricultural drains irrigated with reclaimed water. Conversely, NO3− concentrations in river and agricultural drains were significantly lower in areas farther away from urban centers. Two major NO3− sources were identified using chemical and isotope tracers: fertilizers, with low [lower case delta]15N [delta fifteen nitrogen] and high [lower case delta]18O [delta eighteen oxygen] (average 0.6 and 18.3‰ [permille], respectively), and waste water effluents from cities, with high [lower case delta]15N and low [lower case delta]18O (average 10.5 and -5.1‰, respectively). According to nitrogen and oxygen isotope mass balance constraints, waste effluent-derived NO3− contribution was the smallest in upstream locations and accounted for up to 24-47% near Las Cruces compared to fertilizer-derived NO3−. Further downstream, effluent contributions increased and accounted for up to 41-77% between Las Cruces and El Paso. The highest fertilizer-derived NO3− contributions of 90-100% were measured in the agricultural district located below El Paso where reclaimed city water is commonly used for irrigation. Elevated salinity did not appear to control microbial denitrification. In fact, the strongest isotopic evidence of microbial denitrification was observed in water samples showing elevated salinity. Results suggest urban centers are important NO3− contributors into aquatic system of the watershed and microbial processes do not appear to significantly reduce NO3− loads from anthropogenic sources.
Download or read book Oxygen Isotopic Composition of Nitrate Produced by Freshwater Nitrification written by Danielle Boshers and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Identifying sources of nitrate (NO3-) in the environment is important to elucidate causes of water quality impairment and eutrophication. Measurements of naturally occurring stable isotope ratios of nitrogen (15N/14N) and oxygen (18O/16O) in NO3-, can be used to determine the sources, dispersal, and fate of natural and contaminant NO3- in aquatic environments. To this end, it is necessary to know how NO3- isotopologues are modified by biological reactions, as heavy and light isotopes have different reaction rates. One important microbial reaction that influences isotope ratios of NO3- in the environment is nitrifcation, the biological oxidation of ammonium (NH4+) to nitrite (NO2-) then NO3-, the influence of which is not well understood in freshwater systems. The purpose of this study was to determine the influence of the d18O of ambient water on the isotopic composition of NO3- produced by freshwater nitrification. Water was collected from two streams in New England during the fall and spring, which were amended with NH4+ and with increments of 18O-enriched water, and then monitored the isotopic composition of NO2- and NO3- produced by natural consortia of nitrifiers. Although oxidation rates differed between the two stream waters, the final d18O of NO3- produced in both experiments revealed a sensitivity to the d18O of water mediated by (a) isotopic equilibration between water and NO2- and (b) kinetic isotope fractionation during O-atom incorporation from molecular oxygen and water into NO2- and NO3-. Our results concur with seawater incubations and nitrifying culture experiments that have demonstrated analogous sensitivity of the d18O of nitrified NO3- to equilibrium and kinetic O isotope effects (Buchwald et al. 2012). These findings have important implications for interpretations of O isotopes in NO3- source apportionation studies.
Download or read book Stable Nitrogen Isotopes as a Tool for Understanding Nitrogen Cycling Processes and Mechanisms Responsible for Nitrous Oxide Production written by Robin Leslie Sutka and published by . This book was released on 2002 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating the Probability of Elevated Nitrate NO2 NO3 N Concentrations in Ground Water in the Columbia Basin Ground Water Management Area Washington written by Lonna M. Frans and published by . This book was released on 2000 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotopes in the Water Cycle written by Pradeep K. Aggarwal and published by Springer Science & Business Media. This book was released on 2006-01-16 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental isotope and nuclear techniques provide unmatched insights into the processes governing the water cycle and its variability. This monograph presents state of the art applications and new developments of isotopes in hydrology, environmental disciplines and climate change studies. Coverage ranges from the assessment of groundwater resources in terms of recharge and flow regime to studies of the past and present global environmental and climate changes.
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 Topics in Oceanography written by Enrico Zambianchi and published by BoD – Books on Demand. This book was released on 2013-07-10 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oceanography is the par excellence interdisciplinary science thanks to its peculiar setting within a fluid environment that makes connections extremely efficient. The oceans connections are well mirrored in the chapters of this book that share a quite explicit multidisciplinary and multi-environmental character. The book provides chapters on very different topics under very different settings, some with a focused angle, others with a broader approach, yet all sharing the idea that we need to understand the small pieces in order to put together the big picture for a much larger mechanism, the functioning of the ocean as a whole.
Download or read book Residence Times and Nitrate Transport in Ground Water Discharging to Streams in the Chesapeake Bay Watershed written by and published by . This book was released on 2003 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nutrient Concentrations in Surface Water and Groundwater and Nitrate Source Iden Tification Using Stable Isotope Analysis in the Barnegat Bay Little Egg Harbor Water Shed New Jersey 2010 11 written by Christine Wieben and published by Createspace Independent Publishing Platform. This book was released on 2014-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five streams in the Barnegat Bay-Little Egg Harbor (BB- LEH) watershed in southern New Jersey were sampled for nutrient concentrations and stable isotope composition under base-flow and stormflow conditions, and during the growing and nongrowing seasons, to help quantify and identify sources of nutrient loading. Samples were analyzed for concentrations of total nitrogen, ammonia, nitrate plus nitrite, organic nitro- gen, total phosphorus, and orthophosphate, and for nitrogen and oxygen stable isotope ratios. Concentrations of total nitrogen in the five streams appear to be related to land use, such that streams in subbasins characterized by extensive urban development (and histori- cal agricultural land use)-North Branch Metedeconk and Toms Rivers-exhibited the highest total nitrogen concentra- tions (0.84-1.36 milligrams per liter (mg/L) in base flow). Base-flow total nitrogen concentrations in these two streams were dominated by nitrate; nitrate concentrations decreased during storm events as a result of dilution by storm runoff.
