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Nitrogen Cycle Bacteria in Agricultural Soils
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Guillermo Bravo, Paulina Vega-Celedón, Constanza Macaya, Ingrid-Nicole Vasconez, Michael Seeger
Nitrification Nitrification is an essential process in the nitrogen cycle in soils, which involves the biological oxidation of ammonia via nitrite to nitrate in the presence of oxygen by bacteria and archaea (Hernández et al. 2011). Several enzymes participate in the oxidation of reduced nitrogen compounds. The transmembrane enzyme ammonia monooxygenase oxidizes ammonia to hydroxylamine. NH2OH is subsequently oxidized by hydroxylamine oxidoreductase to nitrite (Hernández et al. 2011). Due to the high solubility of nitrate in agricultural systems, nitrification may cause negative effects, generating losses in crop production, and causing water eutrophication. It has been estimated that nitrification produces worldwide losses of 37 Tg of N year–1 in soil (Mosier et al. 2004).
Nitrogen (Nutrient) Trading Tool
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Water Resources and Hydrological Systems, 2020
As climate change continues, the occurrence of extreme events such as droughts and floods, desertification, shrinking water resources and other challenges are beginning to put additional stress on agricultural systems throughout the world. These challenges increase the pressure on these systems to maintain productivity and keep up with the growth in food demand that follows human population growth. Humans are significantly impacting the global nitrogen cycle; these impacts are reflected in, for example, increased concentrations of N2O in the atmosphere, increased nitrate (NO3) levels in groundwater or surface water resources and increased ammonia (NH3) deposition in natural areas. Not only can these reactive nitrogen losses impact human health, as has been previously reported, they can also impact ecosystem health and ecosystem balances.[7–9] Over 20 years ago, the USEPA established that the safe limit for drinking water was 10 mg NO3–N/L[10]; however, a recent paper has reported a positive correlation of NO3–N in drinking water as low as 0.14 mg/L nitrate with a colorectal cancer risk of one in a million and greater risk at higher concentrations.[8]
Basics of Earth Science
Published in Takashiro Akitsu, Environmental Science, 2018
The nitrogen cycle describes the conversion between nitrogen and substances containing nitrogen, and it forms part of the biogeochemical circulation. It is a circulation that includes elements of gas. Nitrogen is an element that constitutes protein and is, in other words, an element of amino acid constituting a protein. It is also contained in nucleic acids such as DNA and RNA. In other words, nitrogen is indispensable to living things, and it is necessary for the establishment of biological communities to exist in relatively large amounts. The largest reservoir of nitrogen is the atmosphere as 78% of the atmosphere is nitrogen gas (N2). Nitrogen gas is a very inert substance and is not available to most living beings. Therefore, nitrogen in the air cannot directly participate in the nitrogen cycle. In practice, this nitrogen is “fixed” by a process called nitrogen fixing in which nitrogen gas is converted to other compounds (nitrate or ammonia), for example, a reaction to produce nitrate (NO3−) or the like from nitrogen and oxygen.
Consumption of water contaminated by nitrate and its deleterious effects on the human thyroid gland: a review and update
Published in International Journal of Environmental Health Research, 2022
Edgar García Torres, Rebeca Pérez Morales, Alberto González Zamora, Efraín Ríos Sánchez, Edgar Héctor Olivas Calderón, José de Jesús Alba Romero, Esperanza Yasmín Calleros Rincón
Nitrogen, obtained through the nitrogen cycle, is the main component necessary for the survival of all organisms (Stevens 2019) thus, it is essential for the synthesis of biomolecules such as proteins, nucleic acids, and chlorophyll formation in plants (Holmes et al. 2019). The entire cycle has been divided into three essential processes which are fixation, nitrification, and denitrification (Stein and Klotz 2016) in which nitrogen can be found in different stable molecules, such as NH3 (ammonia) and NH4 (ammonium). The oxidation of nitrogen, in the nitrification stage of the nitrogen cycle, converts NH3 and NH4 to NO2− (nitrite) and NO3− (nitrate) by the action of nitrifying bacteria, which represents the most stable forms of nitrogen (Takai 2019). Inorganic nitrite and nitrate are ionic compounds present in nature, through soil and water but are also found in volcanic and igneous rocks (ATSDR 2017). These compounds are hydrophilic salts, and as a result of its physical properties, nitrate is colorless, odorless and insipid, making its identification in water difficult and imperceptible to the human being (Khanfar 2010; Almasi et al. 2016). Nitrate is the most stable metabolite and is a chemically nonreactive form of nitrogen, while the nitrogen in the nitrite ion is in an unstable oxidative state (WHO 2017). With this in mind, knowledge of the increase of these compounds in the environment takes relevance due to their relationship with some alterations in human health.
Differences in nitrification and ammonium-oxidising prokaryotes in the process of wetland restoration
Published in Journal of Environmental Science and Health, Part A, 2020
Chunyong Wang, Rui Wu, Yi Song, Jianbo Guo, Ruyin Liu, Yanshan Cui
Nitrification, the oxidation of ammonia to nitrate, is the key element of the nitrogen cycle.[7,8] It has been reported that AOA and AOB could drive the nitrification process to vary degrees in wetlands.[9] The contributions of AOA and AOB to nitrification can be different due to the differences in physiological characteristics.[10] Previous studies have indicated that AOA or AOB drive the nitrification process in soils and sediments.[10–12] However, studies on the relative contributions of AOA and AOB to nitrification are still controversial, especially in wetland ecosystems.