Download or read book Pitfalls in Measuring Nitrous Oxide Production in Nitrifiers written by Nicole Wrage and published by . This book was released on 2003* with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous oxide (N2O) is an important greenhouse gas. At present, it causes 6% of global warming. The atmospheric concentration of N2O continues to increase at a rate of 0.8 ppb per year. The main known sink of N2O is its destruction in the stratosphere to nitric oxide (NO). Via that destruction product, N2O contributes to the decomposition of stratospheric ozone. The most important sources of N2O are the microbial soil processes nitrification and denitrification. Especially after fertilization of the soil, large amounts of N2O can be emitted. Nitrifiers produce N2O by nitrification and by nitrifier denitrification. In nitrification, N2O develops during the oxidation of hydroxylamine (NH2OH). In nitrifier denitrification, nitrifiers reduce nitrite (NO2- ) via N2O to N2. Not much is known about nitrifier denitrification yet. The discovery of several intermediates and enzymes is in line with a suspected similarity between nitrifier denitrification and denitrification. Denitrifiers reduce nitrate (NO3- ) to N2. N2O is an intermediate in that process. It is important to be able to differentiate between N2O produced by the different processes in soils, since they are influenced by different factors. Only with a profound knowledge of the sources is a mitigation of N2O emission from soils possible. The objectives of this study were to quantitatively assess N2O production by nitrifier denitrification under a range of conditions and to come up with a best estimate for N2O produced by nitrifier denitrification in The Netherlands. A review of nitrifier denitrification and related processes in soils (Chapter 2) revealed how important it is to get to know more about this poorly studied pathway. Up to 30% of the total N2O production in soils has been attributed to nitrifier denitrification. Especially low oxygen (O2) conditions coupled with low organic carbon contents might favour this pathway. It was concluded that there was a need to quantify the N2O production by nitrifier denitrification under different conditions. Therefore, a soil study was carried out with different soils in a range of conditions. Rather than leading to new quantitative insights, this study gave rise to questions concerning the prevailing measurement method for nitrifier denitrification (Chapter 3). In this method, the differentiation between nitrification, nitrifier denitrification, denitrification and other soil sources of N2O is based on incubations with combinations of 0.02 kPa acetylene (C2H2) and 100 kPa O2. C2H2 is supposed to inhibit nitrification and nitrifier denitrification without influencing denitrification, and O2 is supposed to inhibit nitrifier denitrification and denitrification, without affecting nitrification. However, this method did not seem to be suitable for all soils. In some conditions, the addition of inhibitors seemed to stimulate the production of N2O compared to the controls. Furthermore, negative fluxes were calculated for some sources of N2O, especially for nitrifier denitrification (Chapter 3). Due to these methodological difficulties, the objectives of this study were adapted and became i) to test the prominent methodology for quantifying the N2O production by nitrifier denitrification, and ii) to assess the importance of nitrifier denitrification for N2O production in pure cultures of Nitrosomonas europaea and Nitrosospira briensis. N. europaea is often used as a model organism in laboratory studies. It has frequently been found in environments high in N like water treatment plants. N. briensis is better adapted to environments less abundant in N and is common in a number of fertilized arable soils of neutral pH. The first objective has been addressed in Chapter 3, 4 and 5. We have seen in Chapter 3 that the prevailing measurement method using the inhibitors C2H2 (0.02 kPa) and O2 (100 kPa) in different combinations to quantify the N2O production by nitrifier denitrification was not suitable for all soils. Pure culture studies revealed some reasons for the observed problems (Chapter 4 and 5). O2 was not suitable as an inhibitor of nitrifier denitrification, since it also had a negative effect on ammonia oxidation, the first step of nitrification (Chapter 4 and 5). C2H2 only inhibited the N2O production by N. europaea, but not that by N. briensis (Chapter 4). C2H2 did furthermore not inhibit the N2O production by a transformant of N. europaea lacking nitric oxide reductase, an enzyme catalyzing the reduction of nitric oxide to N2O in the nitrifier denitrification pathway (Chapter 5). While it is not clear yet whether the reason for the insensitivity to C2H2 was the same in the transformant and in N. briensis, we can conclude that C2H2 was not reliable as an inhibitor of N2O production by all nitrifiers. Due to the consistent results of soil studies and pure culture experiments, we reach the conclusion that the method using C2H2 and O2 is not suitable for differentiating reliably between sources of N2O in soils. In the past, especially C2H2 has been used extensively to differentiate between nitrification and denitrification in soils. If C2H2 does not inhibit N2O production by nitrifiers reliably, the share of nitrifiers in N2O production might have been underestimated in these studies. The importance of nitrifier denitrification for N2O production has been studied in pure culture experiments (Chapter 4 and 5). In Chapter 4, a study of the production of N2O by pure cultures of N. europaea and N. briensis is described. Large concentrations (100 kPa) of O2 were used to inhibit nitrifier denitrification. The results sugested that nitrifier denitrification was the most important pathway in this respect, causing about 80% of the N2O production by N. europaea and about 65% of that by N. briensis. However, there were indications that nitrification might have been underestimated due to adverse effects of O2 on ammonia oxidation. In Chapter 5, the N2O production was studied in mutants of N. europaea that were deficient in either nitrite reductase (NirK) or nitric oxide reductase (NORB), two enzymes of the nitrifier denitrification pathway. The NirK-deficient cells produced similar amounts of N2O as the wild-type. Since the NirK-deficient cells could not have produced this N2O via the known pathway of nitrifier denitrification, this result suggests that nitrifier denitrification is not so important for N2O production in this mutant. The NORB-deficient cells produced even more N2O, about 60 times as much as the wild-type. At the same time, the NORB-deficient cells consumed NO2-. While side-effects of the mutation on pathways of N2O production cannot be excluded, there are indications for a role of the enzyme NORB in directing ammonia oxidation towards NO2- rather than N2O. Large concentrations of O2 inhibited the N2O production and NO2- consumption in this mutant and might therefore be able to fulfil a role similar to NORB in directing the reaction to NO2-. The N2O production of the NORB-deficient cells was not inhibited by C2H2. This could hint at an unknown pathway of N2O production in nitrifiers (Chapter 5). A sensitivity analysis (Chapter 6) revealed that an inhibition of the N2O reductase of denitrifiers by C2H2 most likely caused some of the observed over- and underestimations of sources of N2O in the soil survey. Furthermore, it is likely that C2H2 only inhibited part of nitrification and nitrifier denitrification and that O2 also partly inhibited nitrification in the soil. This suggests that nitrifiers have probably been underestimated as producers of N2O in studies using C2H2 and O2 as inhibitors. Future studies should further investigate the pathways of N2O production, including the indicated possible unknown pathway of nitrifiers. A combination of stable isotope studies of N and O and incubation studies with inhibitors might enable the differentiation between sources of N2O in soils. Since this study shows that 0.02 kPa C2H2 and 100 kPa O2 are not suitable as inhibitors of different N2O producing processes, alternatives need to be found.

Download or read book Microbial Life in the Cryosphere and Its Feedback on Global Change written by Susanne Liebner and published by Walter de Gruyter GmbH & Co KG. This book was released on 2021-01-18 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cryosphere stands for environments where water appears in a frozen form. It includes permafrost, glaciers, ice sheets, and sea ice and is currently more affected by Global Change than most other regions of the Earth. In the cryosphere, limited water availability and subzero temperatures cause extreme conditions for all kind of life which microorganisms can cope with extremely well. The cryosphere’s microbiota displays an unexpectedly large genetic potential, and taxonomic as well as functional diversity which, however, we still only begin to map. Also, microbial communities influence reaction patterns of the cryosphere towards Global Change. Altered patterns of seasonal temperature fluctuations and precipitation are expected in the Arctic and will affect the microbial turnover of soil organic matter (SOM). Activation of nutrients by thawing and increased active layer thickness as well as erosion renders nutrient stocks accessible to microbial activities. Also, glacier melt and retreat stimulate microbial life in turn influencing albedo and surface temperatures. In this context, the functional resilience of microbial communities in the cryosphere is of major interest. Particularly important is the ability of microorganisms and microbial communities to respond to changes in their surroundings by intracellular regulation and population shifts within functional niches, respectively. Research on microbial life exposed to permanent freeze or seasonal freeze-thaw cycles has led to astonishing findings about microbial versatility, adaptation, and diversity. Microorganisms thrive in cold habitats and new sequencing techniques have produced large amounts of genomic, metagenomic, and metatranscriptomic data that allow insights into the fascinating microbial ecology and physiology at low and subzero temperatures. Moreover, some of the frozen ecosystems such as permafrost constitute major global carbon and nitrogen storages, but can also act as sources of the greenhouse gases methane and nitrous oxide. In this book we summarize state of the art knowledge on whether environmental changes are met by a flexible microbial community retaining its function, or if the altered conditions also render the community in a state of altered properties that affect the Earth’s element cycles and climate. This book brings together research on the cryosphere’s microbiota including permafrost, glaciers, and sea ice in Arctic and Antarctic regions. Different spatial scales and levels of complexity are considered, spanning from ecosystem level to pure culture studies of model microbes in the laboratory. It aims to attract a wide range of parties with interest in the effect of climate change and/or low temperatures on microbial nutrient cycling and physiology.

Download or read book Production of nitric oxide and nitrous oxide by nitrifiers and denitrifiers written by Ronald A. Kester and published by . This book was released on 1997 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Denitrification in Soil and Sediment written by Niels Peter Revsbech and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation of atmospheric nitrogen gas by denitrifying bacteria may represent a significant nutrient sink in natural ecosystems. The rate of denitrification has often been difficult to measure in situ, however, and new methodologies should stimulate research on distribution of activity in space and time. The load of fertilizer nitrogen in modem agriculture has led to increasing nutrient reservoirs in recipient subsoils, aquifers, inland waters and coastal seas. By its conversion of nitrate to atmospheric nitrogen, bacterial denitrification is the only biological process to potentially reduce the impact of increasing nutrient loadings by fertilizer nitrogen in the environment. As part of a scientific program set up by the Danish Ministry of Environment to study environment cycling of nitrogen, phosphorous and organic matter (NPO program) in the light of agricultural, domestic and industrial activities, a symposium on DENITRIFICATION IN SOIL AND SEDIMENT was held at the University of Aarhus, Denmark from 6-9 June 19i\9. On the basis of lectures given at the symposium, this book contains a number of invited contributions on the regulation of denitrification activity (control of enzyme synthesis and activity) and measurement of in situ rates of denitrification in terrestrial and aquatic environments (control factors, diel and seasonal variations, etc). Emphasis has been placed on including the recent improvements in methodologies and current understanding of process regulation, however the book also contains examples of integrated research on the significance of denitrification in environmental nutrient cycling.

Download or read book Methods of Soil Analysis Part 2 written by Richard W. Weaver and published by ACSESS. This book was released on 1994 with total page 1164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil sampling for microbiological analysis; Statistical treatment of microbial data; Soil sterilization; Soil water potencial; Most probable number counts; Light microscopic methods for studying soil microorganisms; Viruses; Recovery and enumeration of viable bacteria; Coliform bacteria; Autotrophic nitrifying bacteria; Free-living dinitrogen-fixing bacteria; Legume nodule symbionts; Anaerobic bacteria and processes; Denitrifiers; Actiomycetes; Frankia and the actinorhizal symbiosis; Filamentous fungi; Vesicular-arbuscular mycorrhizal fungi; Isolation of microorganisms producting antibiotics; Microbiological procedures for biodegradation research; Algae and cyanobacteria; Marking soil bacteria with lacZY; Detection of specific DNA sequences in environmental sample via polymerase chaim reaction; Isolation and purification of bacterial DNA from soil; Microbial biomass; Soil enzymes; Carbon mineralization; Isotopic methods for the study of soil organic matter dynamics ; Practical considerations in the use of nitrogen tracers in agricultural and environmental research; Nitrogen availability; Nitrogen mineralization, immobilization, and nitrification; Dinitrogen fixation; Measuring denitrification in the field; Sulfur oxidation and reduction in soils; Iron and manganese oxidation and reduction.

Download or read book Advances in Nitrogen Cycling in Agricultural Ecosystems written by J. R. Wilson and published by . This book was released on 1988 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen transformation processes; The nitrogen cycle in different systems; Advances in nitrogen methodology; 15N recovery techniques in the field.

Download or read book Forest Growth Responses to the Pollution Climate of the 21st Century written by Lucy J. Sheppard and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue of Water, Air and Soil Pollution offers contributions from the th 18 IUFRO workshop on Air Pollution Stress, Forest Responses to the Pollution st Climate of the 21 Century held in Edinburgh, Scotland, from September 21 to 23,1998. The meeting was held under the auspices of IUFRO, Research Group 7.04.00 chaired by Dr Kevin Percy of Canada. A new session structure was adopted to stimulate activity within the six working parties and a brief resume of these is presented at the front of this volume. The two, one-day plenary sessions were devoted to the two important air pollution issues, nitrogen deposition and ozone. Invited papers were augmented by a large and excellent contribution of poster papers. The final day comprised parallel Working Party Sessions with pre arranged speakers to stimulate discussions. One hundred and thirty one scientists attended, representing 20 countries and 7 IUFRO regions: Northern Europe, Central Europe, Eastern Europe, Mediterranean, North America, Asia and the Western Pacific. Lucy Sheppard David Fowler Water, Air, and Soil Pollution 116: 1, 1999.

Download or read book Nitrogen in the Environment Sources Problems and Management written by R.F. Follett and published by Gulf Professional Publishing. This book was released on 2001-12-03 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen in the Environment: Sources, Problems, and Management is the first volume to provide a holistic perspective and comprehensive treatment of nitrogen from field, to ecosystem, to treatment of urban and rural drinking water supplies, while also including a historical overview, human health impacts and policy considerations. It provides a worldwide perspective on nitrogen and agriculture. Nitrogen is one of the most critical elements required in agricultural systems for the production of crops for feed, food and fiber. The ever-increasing world population requires increasing use of nitrogen in agriculture to supply human needs for dietary protein. Worldwide demand for nitrogen will increase as a direct response to increasing population. Strategies and perspectives are considered to improve nitrogen-use efficiency. Issues of nitrogen in crop and human nutrition, and transport and transformations along the continuum from farm field to ground water, watersheds, streams, rivers, and coastal marine environments are discussed. Described are aerial transport of nitrogen from livestock and agricultural systems and the potential for deposition and impacts. The current status of nitrogen in the environment in selected terrestrial and coastal environments and crop and forest ecosystems and development of emerging technologies to minimize nitrogen impacts on the environment are addressed. The nitrogen cycle provides a framework for assessing broad scale or even global strategies to improve nitrogen use efficiency. Growing human populations are the driving force that requires increased nitrogen inputs. These increasing inputs into the food-production system directly result in increased livestock and human-excretory nitrogen contribution into the environment. The scope of this book is diverse, covering a range of topics and issues from furthering our understanding of nitrogen in the environment to policy considerations at both farm and national scales.

Download or read book The Role of Microbial Communities in Tropical Ecosystems written by Silvia Pajares and published by Frontiers Media SA. This book was released on 2017-01-13 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tropical ecosystems are different in important ways from those of temperate regions. They are a major reservoir of plant and animal biodiversity and play important roles in global climate regulation and biogeochemical cycling. They are also under great threat due to the conversion of tropical ecosystems to other uses. Thus, in the context of global change, it is crucial to understand how environmental factors, biogeographic patterns, and land use changes interact to influence the structure and function of microbial communities in these ecosystems. The contributions to this Research Topic showcase the current knowledge regarding microbial ecology in tropical ecosystems, identify many challenges and questions that remain to be addressed and open up new horizons in our understanding of the environmental and anthropological factors controlling microbial communities in these important ecosystems.

Download or read book The Prokaryotes written by Edward F. DeLong and published by Springer. This book was released on 2014-10-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Prokaryotes is a comprehensive, multi-authored, peer reviewed reference work on Bacteria and Achaea. This fourth edition of The Prokaryotes is organized to cover all taxonomic diversity, using the family level to delineate chapters. Different from other resources, this new Springer product includes not only taxonomy, but also prokaryotic biology and technology of taxa in a broad context. Technological aspects highlight the usefulness of prokaryotes in processes and products, including biocontrol agents and as genetics tools. The content of the expanded fourth edition is divided into two parts: Part 1 contains review chapters dealing with the most important general concepts in molecular, applied and general prokaryote biology; Part 2 describes the known properties of specific taxonomic groups. Two completely new sections have been added to Part 1: bacterial communities and human bacteriology. The bacterial communities section reflects the growing realization that studies on pure cultures of bacteria have led to an incomplete picture of the microbial world for two fundamental reasons: the vast majority of bacteria in soil, water and associated with biological tissues are currently not culturable, and that an understanding of microbial ecology requires knowledge on how different bacterial species interact with each other in their natural environment. The new section on human microbiology deals with bacteria associated with healthy humans and bacterial pathogenesis. Each of the major human diseases caused by bacteria is reviewed, from identifying the pathogens by classical clinical and non-culturing techniques to the biochemical mechanisms of the disease process. The 4th edition of The Prokaryotes is the most complete resource on the biology of prokaryotes. The following volumes are published consecutively within the 4th Edition: Prokaryotic Biology and Symbiotic Associations Prokaryotic Communities and Ecophysiology Prokaryotic Physiology and Biochemistry Applied Bacteriology and Biotechnology Human Microbiology Actinobacteria Firmicutes Alphaproteobacteria and Betaproteobacteria Gammaproteobacteria Deltaproteobacteria and Epsilonproteobacteria Other Major Lineages of Bacteria and the Archaea

Download or read book RAMIRAN 2017 Sustainable Utilisation of Manures and Residue Resources in Agriculture written by Tom Misselbrook and published by Frontiers Media SA. This book was released on 2019-12-30 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook presents highlight papers from the 17th International conference of the Recycling of Agricultural, Municipal and Industrial Residues to Agriculture Network (RAMIRAN) that was held in Wexford, Ireland in September 2017. The book contains a broad range of papers around this multidisciplinary theme covering topics including regional and national organic resource use planning, impact of livestock diet on manure composition, fate and utilisation of excreta from grazing livestock, anaerobic digestion, overcoming barriers to resource reuse, hygienic aspects of residue recycling and impacts on soil health. The overarching theme being addressed is the sustainable recycling of organic residues to agriculture, to promote effective nutrient use and minimise environmental impact.

Download or read book Air Emissions from Animal Feeding Operations written by National Research Council and published by National Academies Press. This book was released on 2003-04-07 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs discusses the need for the U.S. Environmental Protection Agency to implement a new method for estimating the amount of ammonia, nitrous oxide, methane, and other pollutants emitted from livestock and poultry farms, and for determining how these emissions are dispersed in the atmosphere. The committee calls for the EPA and the U.S. Department of Agriculture to establish a joint council to coordinate and oversee short - and long-term research to estimate emissions from animal feeding operations accurately and to develop mitigation strategies. Their recommendation was for the joint council to focus its efforts first on those pollutants that pose the greatest risk to the environment and public health.

Download or read book Greenhouse Gas Sinks written by Dave Reay and published by CABI. This book was released on 2007 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this first comprehensive handbook of the earth's sinks for greenhouse gases, leading researchers from around the world provide an expert synthesis of current understanding and uncertainties. It will be a valuable resource for students, researchers and practitioners in conservation, ecology and environmental studies.

Download or read book Biodiversity and Ecology written by Neil Griffin and published by . This book was released on 2019-06-19 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biodiversity refers to the variation of life forms on earth at the genetic, species and ecosystem level. It varies widely across the globe and from region to region. It is dependent on abiotic characteristics of temperature, precipitation, altitude, etc. Biological diversity exists at various levels. These include taxonomic diversity, ecological diversity, morphological diversity and functional diversity. Ecology is a sub-field of biology that studies the interactions between organisms and the environment. The study of biodiversity, its distribution and population of individual organism groups as well as the interaction between systems of organisms are areas of interest in ecology. It has practical applications in conservation biology, wetland management and natural resource management, among many others. The objective of this book is to give a general view of the different areas of biodiversity and ecology, and their applications. It brings forth some of the most innovative concepts and elucidates the unexplored aspects of these fields. For someone with an interest and eye for detail, this book covers the most significant topics relevant to these fields.

Download or read book Nitrous Oxide and Climate Change written by Keith Smith and published by Routledge. This book was released on 2010-08-12 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous oxide, N2O, is the third most important (in global warming terms) of the greenhouse gases, after carbon dioxide and methane. As this book describes, although it only comprises 320 parts per billion of the earth's atmosphere, it has a so-called Global Warming Potential nearly 300 times greater than that of carbon dioxide. N2O emissions are difficult to estimate, because they are predominantly biogenic in origin. The N2O is formed in soils and oceans throughout the world, by the microbial processes of nitrification and denitrification, that utilise the reactive N compounds ammonium and nitrate, respectively. These forms of nitrogen are released during the natural biogeochemical nitrogen cycle, but are also released by human activity. In fact, the quantity of these compounds entering the biosphere has virtually doubled since the beginning of the industrial age, and this increase has been matched by a corresponding increase in N2O emissions. The largest source is now agriculture, driven mainly by the use of synthetic nitrogen fertilisers. The other major diffuse source derives from release of NOx into the atmosphere from fossil fuel combustion and biomass burning, as well as ammonia from livestock manure. Some N2O also comes directly from combustion, and from two processes in the chemical industry: the production of nitric acid, and the production of adipic acid, used in nylon manufacture. Action is being taken to curb the industrial point-source emissions of N2O, but measures to limit or reduce agricultural emissions are inherently more difficult to devise. As we enter an era in which measures are being explored to reduce fossil fuel use and/or capture or sequester the CO2 emissions from the fuel, it is likely that the relative importance of N2O in the 'Kyoto basket' of greenhouse gases will increase, because comparable mitigation measures for N2O are inherently more difficult, and because expansion of the land area devoted to crops, to feed the increasing global population and to accommodate the current development of biofuels, is likely to lead to an increase in N fertiliser use, and thus N2O emission, worldwide. The aim of this book is to provide a synthesis of scientific information on the primary sources and sinks of nitrous oxide and an assessment of likely trends in atmospheric concentrations over the next century and the potential for mitigation measures.

Download or read book Nitrogen Isotope Techniques written by Roger Knowles and published by Academic Press. This book was released on 1992-10 with total page 336 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 The California Nitrogen Assessment written by Thomas P. Tomich and published by Univ of California Press. This book was released on 2016-06-14 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen is indispensable to all life on Earth. However, humans now dominate the nitrogen cycle, and nitrogen emissions from human activity have real costs: water and air pollution, climate change, and detrimental effects on human health, biodiversity, and natural habitats. Too little nitrogen limits ecosystem processes, while too much nitrogen transforms ecosystems profoundly. The California Nitrogen Assessment is the first comprehensive account of nitrogen flows, practices, and policies for California, encompassing all nitrogen flows—not just those associated with agriculture—and their impacts on ecosystem services and human wellbeing. How California handles nitrogen issues will be of interest nationally and internationally, and the goal of the assessment is to link science with action and to produce information that affects both future policy and solutions for addressing nitrogen pollution. This book also provides a model for application of integrated ecosystem assessment methods at regional and state (subnational) levels.