Download or read book Utilization and Production of N b2 s0 by Denitrifiers Isolated from Different Soil Environments and Effect of PH on the Rates and Products of Denitrification written by Gilbert Uwahamaka Okereke and published by . This book was released on 1978 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Utilization and Production of N20 by Denitrifiers Isolated from Different Soil Environments and Effect of PH on the Rates and Products of Denitrification written by Gilbert Uwahamaka Okereke and published by . This book was released on 1978 with total page 0 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 Characterization of Soil Denitrifier Diversity written by Constance A. Roco and published by . This book was released on 2015 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Denitrification is a part of the global nitrogen cycle in which reactive nitrogen in the biosphere is returned to the atmosphere, and is mediated by diverse communities of microorganisms. The work in this thesis was undertaken to gain a greater understanding of the ecology of denitrifying microorganisms. A combination of bioinformatic analysis of denitrification genes in pure cultures and environmental samples, as well as experimental work with denitrifying bacterial cultures and soil microcosms was performed to understand the relationship between genes and ecosystems in denitrification. First, we examined the diversity of denitrifiers in soil through genome sequencing of microbial isolates coupled to denitrification gas kinetic measurements. The results suggest that partial denitrifiers are common among soil bacteria and it was demonstrated that nitrogen oxide production could not always be predicted by the genetic potential of the isolates. This reveals there are different regulatory effects on each step of the denitrification pathway, which dictate the accumulation of denitrification products. Secondly, the prevalence of dissimilatory reduction of nitrate under aerobic conditions in soil was assessed. Bacteria capable of aerobic nitrate reduction were easily isolated and found to reduce nitrate at oxygen concentrations greater than levels associated with the onset of nitrite reduction and the genomic analysis of the nitrate reductase genes revealed a wide diversity of physiological controls. Finally, a soil microcosm study was performed to determine the influence of oxygen on denitrification gas kinetics and denitrifier community structure. Comparison of soils exposed to oxic, short anoxic and long anoxic conditions revealed the oxic soils had fastest denitrification rates, indicating denitrifiers were not hindered by oxic conditions. The genetic community structure, characterized through metagenomic and metatranscriptomic analysis, was shown to be an important factor in determining denitrification rates and end product ratios. In conclusion, denitrification is a complex pathway of ecological importance that is controlled by the interaction between genes and environmental factors. In order to develop useful tools to mitigate reactive nitrogen and other climate-forcing nitrogen species, a comprehensive understanding of the regulatory network of denitrification with respect to microbial physiology and environmental interactions is needed.
Download or read book Field Measurement of Denitrification written by Dennis E. Rolston and published by . This book was released on 1977 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrogen Removal Characteristics of Aerobic Denitrifying Bacteria and Their Applications in Nitrogen Oxides Emission Mitigation written by Maosheng Zheng and published by Springer. This book was released on 2018-11-02 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically investigates the nitrogen removal characteristics of two screened aerobic denitrifying bacteria and their applications in nitrogen oxides emissions reduction. It reveals that Pseudomonas stutzeri PCN-1 possesses excellent capacity for aerobic nitrogen removal, regardless of whether nitrate, nitrite or N2O were taken as denitrification substrates. It also demonstrates that the rapid N2O reduction is due to the coordinate expression of denitrification genes. Further, the book discusses the bioaugmentation experiments conducted in denitrifying SBR and a pilot-scale Carrousel oxidation ditch, which confirmed that the strain could significantly enhance denitrification performance, reduce N2O emission and improve system stability. The second strain, P.aeruginosa PCN-2 accumulated negligible NO during aerobic nitrate and nitrite removal and efficiently removed NO from flue gas. This study is of great significance for potential applications of aerobic denitrification in mitigating nitrogen oxides emissions from biological nitrogen removal systems.
Download or read book Enzymatic Versus Nonenzymatic Denitrification written by Lee A. Bulla and published by . This book was released on 1968 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Denitrification is classically defined as the microbial reduction of nitrate and nitrite with the liberation of molecular nitrogen and, in some instances, nitrous oxide. The sequence of reactions in which nitrogen is evolved as an end-product is essentially a respiratory mechanism in which nitrate and/or nitrite replaces molecular oxygen. The organisms which are capable of such activities are termed facultative aerobes. However, denitrification is not the only means by which microorganisms reduce nitrate and nitrite. Microorganisms also reduce these anions to the ammonium level for incorporation as cellular nitrogen. The process of denitrification by organisms is a biological one and is supplemented in the soil by another series of reactions not involving biological mechanisms. This form of denitrification is nonbiologically mediated via nonenzymatic avenues of soil nitrogen loss. One of the end-products of this nonenzymatic process is different. The characteristic gaseous end-products are molecular nitrogen and nitric oxide whereas the enzymatic route is characterized by the end-products nitrogen and nitrous oxide. Studies were carried out in an attempt to determine the magnitude of nitrogen loss, mediated via biological (enzymatic) and nonbiological systems (nonenzymatic) to verify, using appropriate tracer techniques, the origin of the nitrogen gases evolved in each case, and to provide a further evaluation of the effect of pH as well as on other soil characteristics and environmental factors on nitrite and nitrate decomposition. By using sterile soils amended with 15N labeled sodium nitrite it was shown that nonbiological denitrification is significant in the nitrogen cycle. To compare this nonenzymatic process with enzymatic denitrification, several soil types as well as a bacterium isolated from marine sediment were used. This gram negative, polarly flagellated bacterium was found to be unique in that it degrades nitrite and nitrate, producing nitrogen gas. Gases evolved from nitrite under sterile conditions were nitrogen and nitric oxide, but no gas was evolved from nitrate. From nonsterile soil, nitrate yielded nitrogen and nitrous oxide. This suggests that nitrite, a critical intermediate in nitrification and denitrification, is degraded nonbiologically and that nitrate, unless reduced to nitrite, cannot be degraded nonbiologically. Hydrogen ion concentration alone cannot fully explain the instability of nitrite in a sterile soil system. It was found that cation exchange capacity, water tension, organic matter, and clay fraction as well as pH are involved in both enzymatic and nonenzymatic denitrification. The reaction sequences of enzymatic and non-enzymatic denitrification appear to be different and unrelated. It is concluded that nonbiological route(s) of soil nitrogen loss must be given equal emphasis in the classical denitrification pathway. Because nitrogen represents a major end-product of the non-enzyme mediated breakdown of nitrite-nitrogen, it becomes difficult to differentiate between the relative contribution of these routes of soil nitrogen loss. However, it does become clear that with nitrate and nitrite-nitrogen, greater field losses of nitrogen occur than had been previously considered possible, particularly since pH represents only one soil factor influencing the conversion of nitrate or nitrite salts to the gaseous state.
Download or read book Denitrification written by J. W. Payne and published by John Wiley & Sons. This book was released on 1981-09-23 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: New York ; Toronto : Wiley & Sons, c1981.
Download or read book Ammonia oxidizer and Denitrifier Populations in Boreal Forest Soils of Differing Nitrogen Availability written by Marci S. Burton and published by . This book was released on 2013 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrification and denitrification are major biological processes transforming nitrogen (N) in soils to plant available N, highly leachable nitrate (NO3−) and gaseous N oxides. Although many studies in the past have studied N cycling communities, the effect of increased N inputs on ammonia-oxidizer and denitrifier population dynamics is still under active investigation. The purpose of this study was to examine the variation of ammonia-oxidizer and denitrifier populations in boreal forest soils providing markedly different localized sources of N availability. Here, we sampled along a natural N-availability gradient, characteristic of the inherent variation in N supply and plant productivity in a boreal forest, and in a long-term fertilized site receiving three levels of N fertilizer, of which the highest was terminated over 10 years ago. Quantitative PCR of archaeal (AOA) and bacterial (AOB) ammonia-oxidizer genes (amoA) and denitrifier genes (nitrite reductase, nirS and nirK; nitrous oxide reductase, nosZ) was used to quantify the populations. In these boreal soils the abundance of AOB amoA dominated over AOA amoA. The size of the AOB population was significantly affected by fertilization application, whereas AOA was not; however, AOA amoA gene copies did increase in response to the high mineralization rates at the high N site along the natural gradient. Our findings indicate that AOB dominate ammonia oxidation in heavily fertilized soils and AOA may contribute significantly to ammonia oxidation in low N environments controlled by N mineralization. The abundance of nirK and nosZ responded most to N additions, but nirS did not, suggesting nirK-bearing denitrifiers dominate these high organic matter containing, well-drained soils. The size of the nirK and nosZ functional groups increased with increasing N availability at all sites. It was found that differences in gene copies per gram of soil could not be explained directly by increased NO3− concentrations but, rather indirectly, through an increase in organic matter substrate quality. In fact, the increased organic matter quality explained the high denitrifier population after fertilization cessation suggesting a resilient effect of fertilization lasting over a decade; whereas, the ammonia-oxidizer community returned to baseline population size after N fertilization was stopped. The community size results along the natural gradient were combined with previously published data on potential nitrification and denitrification rates. It was found that the difference in ammonia-oxidizer and denitrifier populations was positively related to differences in process rates. The study of these functional genes provides insight into the variability of the microbial community populations responsible for regulating important steps in the N cycle.
Download or read book Biochar for Environmental Management written by Dr. Johannes Lehmann and published by Earthscan. This book was released on 2009 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Biochar is the carbon-rich product when biomass (such as wood, manure, or crop residues) is heated in a closed container with little or no available air. It can be used to improve agriculture and the environment in several ways, and its stability in soil and superior nutrient-retention properties make it an ideal soil amendment to increase crop yields. In addition to this, biochar sequestration, in combination with sustainable biomass production, can be carbon-negative and therefore used to actively remove carbon dioxide from the atmosphere, with major implications for mitigation of climate change. Biochar production can also be combined with bioenergy production through the use of the gases that are given off in the pyrolysis process.This book is the first to synthesize the expanding research literature on this topic. The book's interdisciplinary approach, which covers engineering, environmental sciences, agricultural sciences, economics and policy, is a vital tool at this stage of biochar technology development. This comprehensive overview of current knowledge will be of interest to advanced students, researchers and professionals in a wide range of disciplines"--Provided by publisher.
Download or read book Influence of Denitrification in Aquatic Sediments on the Nitrogen Content of Natural Waters written by J. F. van Kessel and published by Bernan Press(PA). This book was released on 1976-01-01 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stormwater Biofiltration Systems written by Belinda E. Hatt and published by . This book was released on 2009 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Approaches for Bioremediation of Organic Pollution written by Raffi Fass and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 42nd OHOLO Conference held in Eilat, Israel, May 3-7, 1998
Download or read book Principles and Practices of Rice Production written by Surajit K. De Datta and published by Int. Rice Res. Inst.. This book was released on 1981 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Endospore forming Soil Bacteria written by Niall A. Logan and published by Springer Science & Business Media. This book was released on 2011-07-06 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerobic endospore-forming bacteria are found in soils of all kinds, ranging from acid to alkaline, hot to cold, and fertile to desert. It is well known that endospores confer special properties upon their owners and play dominant parts in their life cycles and dispersal, and much has been written about the spores, genetics, and economic importance of these organisms. Much has also been written about soil ecology, but there is a relative dearth of literature that brings together different aspects of the behaviour and characters of endospore-formers with their contributions to soil ecosystems. This Soil Biology volume fills that gap. Following chapters that describe the current classification of these organisms, that review methods for their detection and for studying their life cycles in soils, and that examine their dispersal, other chapters show that they are active and dynamic members of soil floras that interact widely with other soil inhabitants, with roles in nitrogen fixation, denitrification, and soil remediation.
Download or read book Process Design Manual for Nitrogen Control written by United States. Environmental Protection Agency. Office of Technology Transfer and published by . This book was released on 1975 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Horizons in Biotechnology written by S. Roussos and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: The practice of biotechnology, though different in style, scale and substance in globalizing science for development involves all countries. Investment in biotechnology in the industrialised, the developing, and the least developed countries, is now amongst the widely accepted avenues being used for economie development. The simple utilization of kefir technology, the detoxification of injurious chemical pesticides e.g. parathion, the genetic tailoring of new crops, and the production of a first of a kind of biopharmaceuticals illustrate the global scope and content of biotechnology research endeavour and effort. In the developing and least developed nations, and in which the 9 most populous countries· are encountered, problems concerning management of the environment, food security, conservation of human health resources and capacity building are important factors that influence the path to sustainable development. Long-term use of biotechnology in the agricultural, food, energy and health sectors is expected to yield a windfall of economic, environmental and social benefits. Already the prototypes of new medicines and of prescription fruit vaccines are available. Gene based agriculture and medieine is increasingly being adopted and accepted. Emerging trends and practices are reflected in the designing of more efficient bioprocesses, and in new research in enzyme and fermentation technology, in the bioconversion of agro industrial residues into bio-utility products, in animal healthcare, and in the bioremediation and medical biotechnologies. Indeed, with each new day, new horizons in biotechnology beckon.
