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 15N Tracing of Microbial Assimilation Partitioning and Transport of Fertilisers in Grassland Soils written by Alice Fiona Charteris and published by Springer Nature. This book was released on 2019-10-28 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents innovative research on soil nitrogen cycling and nitrate leaching with a view to improving soil management and fertiliser nitrogen use efficiency and reducing nitrogen leaching losses. In this regard, nitrogen-15 (15N)-labelled fertiliser was used as a biochemical and physical stable isotope tracer in laboratory and field experiments. The major outcome of the research was the development, validation and application of a new compound-specific amino acid 15N stable isotope probing method for assessing the assimilation of fertiliser nitrogen by soil microbial biomass. The novelty of the method lies in its tracing of incorporated nitrogen into newly biosynthesised microbial protein in time-course experiments using gas chromatography-combustion-isotope ratio mass spectrometry. The approach provides previously unattainable insights into the microbial processing of different nitrogen fertilisers in different soils. Further, it identifies the mechanistic link between molecular-scale processes and observations of field-scale fertiliser nitrogen immobilisation studies. The method and the results presented here will have far-reaching implications for the development of enhanced recommendations concerning farm-based soil management practices for increasing soil productivity and reducing nitrogen losses, which is essential to minimising environmental impacts.

Download or read book Soil Organic Matter and Feeding the Future written by Rattan Lal and published by CRC Press. This book was released on 2021-12-09 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil organic matter (SOM) is the primary determinant of soil functionality. Soil organic carbon (SOC) accounts for 50% of the SOM content, accompanied by nitrogen, phosphorus, and a range of macro and micro elements. As a dynamic component, SOM is a source of numerous ecosystem services critical to human well-being and nature conservancy. Important among these goods and services generated by SOM include moderation of climate as a source or sink of atmospheric CO2 and other greenhouse gases, storage and purification of water, a source of energy and habitat for biota (macro, meso, and micro-organisms), a medium for plant growth, cycling of elements (N, P, S, etc.), and generation of net primary productivity (NPP). The quality and quantity of NPP has direct impacts on the food and nutritional security of the growing and increasingly affluent human population. Soils of agroecosystems are depleted of their SOC reserves in comparison with those of natural ecosystems. The magnitude of depletion depends on land use and the type and severity of degradation. Soils prone to accelerated erosion can be strongly depleted of their SOC reserves, especially those in the surface layer. Therefore, conservation through restorative land use and adoption of recommended management practices to create a positive soil-ecosystem carbon budget can increase carbon stock and soil health. This volume of Advances in Soil Sciences aims to accomplish the following: Present impacts of land use and soil management on SOC dynamics Discuss effects of SOC levels on agronomic productivity and use efficiency of inputs Detail potential of soil management on the rate and cumulative amount of carbon sequestration in relation to land use and soil/crop management Deliberate the cause-effect relationship between SOC content and provisioning of some ecosystem services Relate soil organic carbon stock to soil properties and processes Establish the relationship between soil organic carbon stock with land and climate Identify controls of making soil organic carbon stock as a source or sink of CO2 Connect soil organic carbon and carbon sequestration for climate mitigation and adaptation

Download or read book Identifying Sources of Subsurface Nitrate Pollution with Stable Nitrogen Isotopes written by Timothy J. Wolterink and published by . This book was released on 1979 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The nitrogen ([delta]15N) and oxygen ([delta]18O) isotopic compositions of nitrate in the environment are primarily a function of the source of the nitrate. The ranges of isotopic compositions for nitrate resulting from common sources are outlined in Figure 1 from Kendall (1998). As noted on Figure 1, processes such as microbial metabolism can modify the isotopic compositions of the nitrate, but the effects of these processes are generally predictable. At Hanford, nitrate and other nitrogenous compounds were significant components of most of the chemical processes used at the site. Most of the oxygen in nitrate chemicals (e.g., nitric acid) is derived from atmospheric oxygen, giving it a significantly higher [delta]18O value (+23.5{per_thousand}) than naturally occurring nitrate that obtains most of its oxygen from water (the [delta]18O of Hanford groundwater ranges from -14{per_thousand} to -18{per_thousand}). This makes it possible to differentiate nitrate from Hanford site activities from background nitrate at the site (including most fertilizers that might have been used prior to the Department of Energy plutonium production activities at the site). In addition, the extreme thermal and chemical conditions that occurred during some of the waste processing procedures and subsequent waste storage in select single-shell tanks resulted in unique nitrate isotopic compositions that can be used to identify those waste streams in soil and groundwater at the site (Singleton et al., 2005; Christensen et al., 2007). This report presents nitrate isotope data for soil and groundwater samples from the Hanford 200 Areas and discusses the implications of that data for potential sources of groundwater contamination.

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.

Download or read book Isotopic Compositions and Sources of Nitrate in Ground Water from Western Salt River Valley Arizona written by D. J. Gellenbeck and published by . This book was released on 1994 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nitrate Ions and Nitrous Oxide at the Strawberry Creek Catchment written by Marlin Rempel and published by . This book was released on 2008 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrate (NO3) contamination in agricultural watersheds is a widespread problem that threatens local drinking supplies and downstream ecology. Dual isotopes of NO3− ([delta]15N and [delta]18O) have been successfully used to identify sources of NO3 contamination and nitrogen (N)-cycle processes in agricultural settings. From 1998 to 2000, tile drainage and stream waters at the Strawberry Creek Catchment were sampled for NO3− concentration and isotopes. The results suggest that tile NO3 were mainly derived from soil organic matter and manure fertilizers, and that they were not extensively altered by denitrification. NO3− concentrations and isotopes in the stream oscillated between the influence of tile inputs, during periods of higher basin discharge, and groundwater inputs, during low basin discharge. The affect of denitrification was evident in stream NO3− samples. Sources and processes of dissolved NO3− and N2O were explored using concentrations and stable isotopes during the 2007 Springmelt and 2008 mid-winter thaw events. Tiles are a source of NO3− to the stream during both events and concentrations at the outflow are above the 10 mg N/L drinking water limit during the 2008 mid-winter thaw. The stream was a source of N2O to the atmosphere during both events. [delta]15N and [delta]18O of N2O reveal that N2O is produced from denitrification during both events. [delta]18O:[delta]15N slopes measured in N2O were due to the influence of substrate consumption (tiles) and gas exchange (stream). The stable isotopes of dissolved NO3− and N2O were also characterized during non-melt conditions (October 2006 to June 2007 and Fall 2007) at the Strawberry Creek catchment. Again, the purpose was to determine the sources and processes responsible for the measured concentrations and isotopic signatures. The isotope data suggests that N2O was produced by denitrification. Furthermore, NO3− consumption and gas exchange altered the original N2O signature. Isotopic distinction between soil gas N2O and dissolved N2O is suggestive of different production mechanisms between the unsaturated and saturated zones. Since the range of dissolved N2O isotopes from the Strawberry Creek catchment are relatively constraned, definition of the local isotopic signature of secondary, agricultural N2O sources was possible.

Download or read book Nutrient concentrations in surface water and groundwater and nitrate source identification using stable isotope analysis in the Barnegat Bay Little Egg Harbor Watershed New Jersey 2010 11 written by Christine Wieben and published by CreateSpace. This book was released on 2013 with total page 52 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.

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 Nitrogen Isotopes in Deep Time written by Colin Mettam and published by Cambridge University Press. This book was released on 2021-02-18 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen is an essential nutrient for life, and its sources and cycling have varied over earth history. Stable isotope ratios of nitrogen compounds (expressed as δ15N, in ‰) are preserved in the sedimentary record and track these changes, providing important insights into associated biogeochemical feedbacks. Here we review the use of nitrogen stable isotope geochemistry in unravelling the evolution of the global N cycle in deep time. We highlight difficulties with preservation, unambiguous interpretations, and local versus global effects. We end with several case studies illustrating how depositional and stratigraphic context is crucial in reliably interpreting δ15N records in ancient marine sediments, both in ancient anoxic (Archean) and more recent well oxygenated (Phanerozoic) environments.

Download or read book Determining the Source of Nitrate in Ground Water by Nitrogen Isotope Studies written by Charles W. Kreitler and published by . This book was released on 1975 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Isotope Tracers of Nitrogen Sources to the Neuse River North Carolina written by and published by . This book was released on 1990 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: