what process releases nitrogen gas into the atmosphere
The nitrogen cycle
title: Nitrogen cycle text: Nitrogen cycle The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because title: Nitrogen cycle text: human activities. It is a reactant in the atmosphere, where it acts as an aerosol, decreasing air quality and clinging to water droplets, eventually resulting in nitric acid (HNO) that produces acid rain. Atmospheric ammonia and nitric acid also damage respiratory systems. The very high temperature of lightning naturally produces small amounts of NO, NH, and HNO, but high-temperature combustion has contributed to a 6- or 7-fold increase in the flux of NO to the atmosphere. Its production is a function of combustion temperature - the higher the temperature, the more NO is produced. Fossil fuel combustion is a primary title: Nitrogen text: products of the amino acids ornithine and lysine, respectively, in decaying proteins. Nitrogen gas is an industrial gas produced by the fractional distillation of liquid air, or by mechanical means using gaseous air (pressurised reverse osmosis membrane or pressure swing adsorption). Nitrogen gas generators using membranes or pressure swing adsorption (PSA) are typically more cost and energy efficient than bulk delivered nitrogen. Commercial nitrogen is often a byproduct of air-processing for industrial concentration of oxygen for steelmaking and other purposes. When supplied compressed in cylinders it is often called OFN (oxygen-free nitrogen). Commercial-grade nitrogen already contains at most 20 ppm title: Nitrogen cycle text: nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. Nitrogen is present in the environment in a wide variety of chemical forms including organic nitrogen, ammonium (NH), nitrite (NO), nitrate (NO), nitrous oxide, (NO), nitric oxide (NO) or inorganic nitrogen gas (N). Organic nitrogen may be in the form of a living organism, humus or in the intermediate products of organic matter decomposition. The processes in the nitrogen cycle title: Nitrogen text: diatomic gas with the formula N. Dinitrogen forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids (DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Many industrially important compounds, such as ammonia, nitric acid,