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15 novembre 2011 2 15 /11 /novembre /2011 02:57

Essential and non-essential nutrients

Nutrients are frequently categorized as essential or nonessential. Essential nutrients are unable to be synthesized internally (either at all, or in sufficient quantities), and so must be consumed by an organism from its environment.Nonessential nutrients are those nutrients that can be made by the body, they may often also be absorbed from consumed food.Sony VAIO VPCEB1BGX/BI Battery

The majority of animals ultimately derive their essential nutrients from plants, though some animals may consume mineral-based soils to supplement their diet.

For humans, these include essential fatty acids, essential amino acids, vitamins, and certain dietary minerals. Oxygen and water are also essential for human survival, but are generally not considered "food" when consumed in isolation.Sony VAIO VPCEB1CGX Battery

Humans can derive energy from a wide variety of fats, carbohydrates, proteins, and ethanol, and can synthesize other needed amino acids from the essential nutrients.

Non-essential substances within foods can still have a significant impact on health, whether beneficial or toxic. Sony VAIO VPCEB1CGX/BI Battery

For example, most dietary fiber is not absorbed by the human digestive tract, but is important in digestion and absorption of otherwise harmful substances. Interest has recently increased in phytochemicals, which include many non-essential substances which may have health benefits.Sony VAIO VPCEB1DGX Battery

Deficiencies and toxicity

An inadequate amount of a nutrient is a deficiency. Deficiencies can be due to a number of causes including inadequacy in nutrient intake called dietary deficiency, or conditions that interfere with the utilization of a nutrient within an organism.Sony VAIO VPCEB1DGX/BI Battery

Some of the conditions that can interfere with nutrient utilization include problems with nutrient absorption, substances that cause a greater than normal need for a nutrient, conditions that cause nutrient destruction, and conditions that cause greater nutrient excretion.Sony VAIO VPCEB1EGX Battery

Nutrient toxicity occurs when an excess of a nutrient does harm to an organism.

In plants five types of deficiency or toxicity symptoms are common:

  • Chlorosis - which is the yellowing of plant tissue caused by a shortage of chlorophyll synthesis.
  • Necrosis - which is the death of plant tissue.Sony VAIO VPCEB1EGX/BI Battery
  • Accumulation of anthocynanin - which produces a purple or reddish colorization of foliage and/or stems.
  • Lack of new growth.
  • Stunting or reduced growth - where new growth is stunted or reduced.Sony VAIO VPCEB1FGX Battery

Oversupply of plant nutrients in the environment can cause excessive plant and algae growth. Eutrophication, as this process is called, may cause imbalances in population numbers and other nutrients that can be harmful to certain species. For example, an algal bloom can deplete the oxygen available for fish to breathe. Causes include water pollution from sewage or runoff from farms (carrying excess agricultural fertilizer). Sony VAIO VPCEB1FGX/BI Battery

Nitrogen and phosphorus are most commonly the limiting factor in growth, and thus the most likely to trigger eutrophication when introduced artificially.

Reactive nitrogen species (RNS) are a family of antimicrobial molecules derived from nitric oxide Sony VAIO VPCEB1GGX Battery

(·NO) and superoxide (O2·?) produced via the enzymatic activity of inducible nitric oxide synthase 2 (NOS2) and NADPH oxidase respectively. NOS2 is expressed primarily in macrophages after induction bycytokines and microbial products, notably interferon-gamma (IFN-?) and lipopolysaccharide (LPS).Sony VAIO VPCEB1GGX/BI Battery

Reactive nitrogen species act together with reactive oxygen species (ROS) to damage cells, causingnitrosative stress. Therefore, these two species are often collectively referred to as ROS/RNS.

Reactive nitrogen species are also continuously produced in plants as by-products of aerobic metabolismor in response to stress.Sony VAIO VPCEB1HGX Battery

Types

RNS are produced in animals starting with the reaction of nitric oxide (·NO) with superoxide (O2·?) to form peroxynitrite (ONOO?):

  • ·NO (nitric oxide) + O2·? (super oxide) ? ONOO? (peroxynitrite)

Superoxide anion (O2-) is a reactive oxygen species that reacts quickly with nitric oxide (NO) in the vasculature. Sony VAIO VPCEB1HGX/BI Battery

The reaction produces peroxynitrite and depletes the bioactivity of NO. This is important because NO is a key mediator in many important vascular functions including regulation of smooth muscle tone and blood pressure, platelet activation, and vascular cell signaling.Sony VAIO VPCEB1JFX Battery

Peroxynitrite itself is a highly reactive species which can directly react with various biological targets and components of the cell including lipids, thiols, amino acid residues, DNA bases, and low-molecular weight antioxidants. However, these reactions happen at a relatively slow rate. This slow reaction rate allows it to react more selectively throughout the cell. Sony VAIO VPCEB1JFX/B Battery

Peroxynitrite is able to get across cell membranes to some extent through anion channels.  Additionally peroxynitrite can react with other molecules to form additional types of RNS including nitrogen dioxide (·NO2) and dinitrogen trioxide (N2O3) as well as other types of chemically reactivefree radicals. Important reactions involving RNS include:Sony VAIO VPCEB1JFX/G Battery

  • ONOO? + H+ ? ONOOH (peroxynitrous acid) ? ·NO2 (nitrogen dioxide) + ·OH (hydroxyl radical)
  • ONOO? + CO2 (carbon dioxide) ? ONOOCO2? (nitrosoperoxycarbonate)
  • ONOOCO2? ? ·NO2 (nitrogen dioxide) + O=C(O·)O? (carbonate radical)
  • ·NO + ·NO2 is in equilibrium with N2O3 (dinitrogen trioxide) Sony VAIO VPCEB1JFX/L Battery

Biological targets

Peroxynitrite can react directly with proteins that contain transition metal centers. Therefore, it can modify proteins such as hemoglobin, myoglobin, and cytochrone c by oxidizing ferrous heme into its corresponding ferric forms. Sony VAIO VPCEB1JFX/P Battery

Peroxynitrite may also be able to change protein structure through the reaction with various amino acids in the peptide chain. The most common reaction with amino acids is cysteine oxidation. Another reaction is tyrosine nitration; however peroxynitrite does not react directly with tyrosine.Sony VAIO VPCEB1JFX/W Battery

Tyrosine reacts with other RNS that are produced by peroxynitrite. All of these reactions affect protein structure and function and thus have the potential to cause changes in the catalytic activity of enzymes, altered cytoskeletal organization, and impaired cell signal transduction.Sony VAIO VPCEB1KGX Battery

Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillationof liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4. Liquid nitrogen is often referred to by the abbreviation, LN2 or "LIN" or "LN" and has the UN number1977.Sony VAIO VPCEB1KGX/B Battery

At atmospheric pressure, liquid nitrogen boils at 77K (-196°C; -321°F) and is a cryogenic fluid which can cause rapid freezingon contact with living tissue, which may lead to frostbite. When appropriately insulated from ambient heat, liquid nitrogen can be stored and transported, for example in vacuum flasks. Sony VAIO VPCEB1KGX/W Battery

Here, the very low temperature is held constant at 77 K by slow boiling of the liquid, resulting in the evolution of nitrogen gas. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks.

Liquid nitrogen can easily be converted to the solid by placing it in a vacuum chamber pumped by a rotary vacuum pump.Sony VAIO VPCEB1LFX Battery

Liquid nitrogen freezes at 63 K (?210 °C; ?346 °F). Despite its reputation, liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect, known as the Leidenfrost effect, applies to any liquid in contact with an object significantly hotter than its boiling point.Sony VAIO VPCEB1LFX/BI Battery

More rapid cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen than into liquid nitrogen alone.

Nitrogen was first liquefied at the Jagiellonian University on 15 April 1883 by Polish physicists, Zygmunt Wróblewski and Karol Olszewski.Sony VAIO VPCEB1LFX/WI Battery

Liquid nitrogen is a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:Sony VAIO VPCEB1MFX Battery

  • in cryotherapy for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis
  • as a coolant for CCD cameras in astronomy
  • to store cells at low temperature for laboratory work
  • in cryogenics
  • as a source of very dry nitrogen gas  Sony VAIO VPCEB1MFX/BI Battery
  • for the immersion freezing and transportation of food products
  • for the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials
  • as a method of freezing water pipes in order to work on them in situations where a valve is not available to block water flow to the work area  Sony VAIO VPCEB1NFX Battery
  • in the process of promession, a way to dispose of the dead
  • for cooling a high-temperature superconductor to a temperature sufficient to achieve superconductivity
  • for the cryonic preservation in the hope of future reanimation.
  • to preserve tissue samples from surgical excisions for future studies
  • to shrink-weld machinery parts together  Sony VAIO VPCEB1NFX/B Battery
  • as a coolant for vacuum pump traps and in controlled-evaporation processes in chemistry.
  • as a coolant to increase the sensitivity of infrared homing seeker heads of missiles such as the Strela 3
  • as a coolant to temporarily shrink mechanical components during machine assembly and allow improved interference fits
  • as a coolant for computers  Sony VAIO VPCEB1NFX/L Battery
  • in food preparation, such as for making ultra-smooth ice cream.

Safety

Since the liquid to gas expansion ratio of nitrogen is 1:694 at 20C, a tremendous amount of force can be generated if liquid nitrogen is rapidly vaporized. Sony VAIO VPCEB1NFX/P Battery

In an incident in 2006 at Texas A&M University, the pressure-relief devices of a tank of liquid nitrogen were malfunctioning and later sealed. As a result of the subsequent pressure buildup, the tank failed catastrophically and exploded. The force of the explosion was sufficient to propel the tank through the ceiling immediately above it.Sony VAIO VPCEB1NFX/W Battery

Because of its extremely low temperature, careless handling of liquid nitrogen may result in cold burns.

As liquid nitrogen evaporates it will reduce the oxygen concentration in the air and might act as an asphyxiant, especially in confined spaces. Nitrogen is odorless, colorless and tasteless, and may produce asphyxia without any sensation or prior warning.Sony VAIO VPCEB1PFX Battery

A laboratory assistant died in Scotland in 1999, apparently from asphyxiation, possibly caused by liquid nitrogen spilled in a basement storage room.

Vessels containing liquid nitrogen can condense oxygen from air. The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point = 90 K) as the nitrogen evaporates, and can cause violent oxidation of organic material.Sony VAIO VPCEB1PFX/B Battery

The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification. Sony VAIO VPCEB1QGX Battery

The majority of Earth's atmosphere (approximately 78%) is nitrogen,  making it the largest pool of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. Sony VAIO VPCEB1QGX/BI Battery

The nitrogen cycle is of particular interest to ecologists because 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.Sony VAIO VPCEB1RGX Battery

A 2011 study has cast doubt on the traditional model of the nitrogen cycle described below; nitrogen from rocks may also be a significant source not previously included.

Ecological function

Nitrogen is essential for many processes; it is crucial for any life on Earth. It is a component in all amino acids, as incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. Sony VAIO VPCEB1RGX/BI Battery

In plants, much of the nitrogen is used in chlorophyll molecules, which are essential for photosynthesisand further growth. Although Earth’s atmosphere is an abundant source of nitrogen, most is relatively unusable by plants. Chemical processing, or naturalfixation (through processes such as bacterial conversion—see rhizobium), are necessary to convert gaseous nitrogen into forms usable by living organisms, which makes nitrogen a crucial component of food production. Sony VAIO VPCEB20 Battery

The abundance or scarcity of this "fixed" form of nitrogen, (also known as reactive nitrogen), dictates how much food can be grown on a piece of land.

The processes of the nitrogen cycle

Nitrogen is present in the environment in a wide variety of chemical forms including organic nitrogen, ammonium (NH4+), nitrite (NO2-), nitrate (NO3-), nitrous oxide(N2O), nitric oxide (NO) or inorganic nitrogen gas (N2).Sony VAIO VPCEC20 Battery

Organic nitrogen may be in the form of a living organism, humus or in the intermediate products of organic matter decomposition. The processes of the nitrogen cycle transform nitrogen from one form to another. Many of those processes are carried out by microbes, either in their effort to harvest energy or to accumulate nitrogen in a form needed for their growth. Sony VAIO VPCEE20 Battery

The diagram above shows how these processes fit together to form the nitrogen cycle.

Nitrogen fixation

Atmospheric nitrogen must be processed, or "fixed" (see page on nitrogen fixation), to be used by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria.Sony VAIO VPCEF20 Battery

These bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is then further converted by the bacteria to make their own organic compounds. Most biological nitrogen fixation occurs by the activity of Mo-nitrogenase, found in a wide variety of bacteria and some Archaea. Sony VAIO VPCF112FX/B Battery

Mo-nitrogenase is a complex two component enzyme that has multiple metal-containing prosthetic groups. Some nitrogen fixing bacteria, such as Rhizobium, live in the root nodules of legumes (such as peas or beans). Here they form a mutualistic relationship with the plant, producing ammonia in exchange for carbohydrates. Sony VAIO VPCF115FG/B Battery

Nutrient-poor soils can be planted with legumes to enrich them with nitrogen. A few other plants can form suchsymbioses. Today, about 30% of the total fixed nitrogen is manufactured in ammonia chemical plants.

Conversion of N2

The conversion of nitrogen (N2) from the atmosphere into a form readily available to plants and hence to animals and humans is an important step in the nitrogen cycle, which distributes the supply of this essential nutrient. Sony VAIO VPCF116FGBI Battery

There are four ways to convert N2 (atmospheric nitrogen gas) into more chemically reactive forms:

  1. Biological fixation: some symbiotic bacteria (most often associated with leguminous plants) and some free-living bacteria are able to fix nitrogen as organic nitrogen. An example of mutualistic nitrogen fixing bacteria are the Rhizobium bacteria, which live in legume root nodules. These species are diazotrophs. An example of the free-living bacteria is Azotobacter.Sony VAIO VPCF117FJ/W Battery
  2. Industrial N-fixation: Under great pressure, at a temperature of 600 C, and with the use of an iron catalyst, hydrogen (usually derived from natural gas or petroleum) and atmospheric nitrogen can be combined to form ammonia (NH3) in the Haber-Bosch process which is used to make fertilizer and explosives.Sony VAIO VPCF117HG/BI Battery
  3. Combustion of fossil fuels: automobile engines and thermal power plants, which release various nitrogen oxides (NOx).
  4. Other processes: In addition, the formation of NO from N2 and O2 due to photons and especially lightning, can fix nitrogen.Sony VAIO VPCF118FJ/W Battery

Assimilation

Plants take nitrogen from the soil, by absorption through their roots in the form of either nitrate ions or ammonium ions. All nitrogen obtained by animals can be traced back to the eating of plants at some stage of the food chain.Sony VAIO VPCF119FC Battery

Plants can absorb nitrate or ammonium ions from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions for incorporation into amino acids, nucleic acids, and chlorophyll. In plants that have a mutualistic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Sony VAIO VPCF119FC/BI Battery

Animals, fungi, and other heterotrophic organisms obtain nitrogen by ingestion of amino acids, nucleotides and other small organic molecules.

Ammonification

When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into ammonium (NH4+), a process called ammonification or mineralization.Sony VAIO VPCF119FJ/BI Battery

Enzymes Involved:

  • GS: Gln Synthetase (Cytosolic & PLastid)
  • GOGAT: Glu 2-oxoglutarate aminotransferase (Ferredoxin & NADH dependent)
  • GDH: Glu Dehydrogenase:

Nitrification

The conversion of ammonium to nitrate is performed primarily by soil-living bacteria and other nitrifying bacteria. In the primary stage of nitrification, the oxidation of ammonium (NH4+) is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites (NO2-). Sony VAIO VPCF11AGJ Battery

Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates (NO3-). It is important for the nitrites to be converted to nitrates because accumulated nitrites are toxic to plant life.

Due to their very high solubility, nitrates can enter groundwater. Sony VAIO VPCF11AHJ Battery

Elevated nitrate in groundwater is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome. Where groundwater recharges stream flow, nitrate-enriched groundwater can contribute to eutrophication, a process that leads to high algal, especially blue-green algal populations and the death of aquatic life due to the algae's excessive demand for oxygen. Sony VAIO VPCF11JFX/B Battery

While not directly toxic to fish life, like ammonia, nitrate can have indirect effects on fish if it contributes to this eutrophication. Nitrogen has contributed to severe eutrophication problems in some water bodies. Since 2006, the application of nitrogen fertilizer has been increasingly controlled in Britain and the United States. Sony VAIO VPCF11M1E Battery

This is occurring along the same lines as control of phosphorus fertilizer, restriction of which is normally considered essential to the recovery of eutrophied waterbodies.

Denitrification

Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. Sony VAIO VPCF11M1E/H Battery

This process is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions. They use the nitrate as an electron acceptor in the place of oxygen during respiration. These facultatively anaerobic bacteria can also live in aerobic conditions.Sony VAIO VPCF11MFX/B Battery

Anaerobic ammonium oxidation

In this biological process, nitrite and ammonium are converted directly into elemental nitrogen (N2) gas. This process makes up a major proportion of elemental nitrogen conversion in the oceans.

Marine nitrogen cycle

The nitrogen cycle is an important process in the ocean as well. While the overall cycle is similar, there are different players and modes of transfer for nitrogen in the ocean.Sony VAIO VPCF11S1E Battery

Nitrogen enters the water through precipitation, runoff, or as N2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N2 so it must undergo nitrogen fixation which is performed predominately by cyanobacteria. Without supplies of fixed nitrogen entering the marine cycle the fixed nitrogen would be used up in about 2000 years. Sony VAIO VPCF11S1E/B Battery

Phytoplankton need nitrogen in biologically available forms for the initial synthesis of organic matter. Ammonia and urea are released into the water by excretion from plankton. Nitrogen sources are removed from the euphotic zone by the downward movement of the organic matter. Sony VAIO VPCF11Z1E Battery

This can occur from sinking of phytoplankton, vertical mixing, or sinking of waste of vertical migrators. The sinking results in ammonia being introduced at lower depths below the euphotic zone. Bacteria are able to convert ammonia to nitrite and nitrate but they are inhibited by light so this must occur below the euphotic zone.Sony VAIO VPCF11Z1E/BI Battery

Ammonification or Mineralization is performed by bacteria to convert the ammonia to ammonium. Nitrification can then occur to convert the ammonium to nitrite and nitrate. Nitrate can be returned to the euphotic zone by vertical mixing and upwelling where it can be taken up by phytoplankton to continue the cycle. N2 can be returned to the atmosphere through denitrification.Sony VAIO VPCF11ZHJ Battery

NH4+ is thought to be the preferred source of fixed nitrogen for phytoplankton because its assimilation does not involve a redox reaction and therefore requires little energy. However NO3 is more abundant so most phytoplankton have adapted to have the enzymes necessary to undertake this reduction (nitrate reductase). Sony VAIO VPCF127HGBI Battery

There are a few notable and well-known exceptions that include Prochlorococcus and some Synechococcus. These species can only take up nitrogen as NH4+.

The nutrients in the ocean are not uniformly distributed. Areas of upwelling provide supplies of nitrogen from below the euphotic zone. Sony VAIO VPCF137HG/BI Battery

Coastal zones provide nitrogen from runoff and upwelling occurs readily along the coast. However, the rate at which nitrogen can be taken up by phytoplankton is decreased in oligotrophicwaters all year-round and temperate water in the summer resulting in lower primary production. The distribution of the different forms of nitrogen varies throughout the oceans as well.Sony VAIO VPC-P111KX/B Battery

Nitrate is depleted in near-surface water except in upwelling regions. Coastal upwelling regions usually have high nitrate and chlorophyll levels as a result of the increased production. However, there are regions of high surface nitrate but low chlorophyll that are referred to as HNLC (high nitrogen, low chlorophyll) regions. Sony VAIO VPC-P111KX/D Battery

As of now the best explanation for HNLC regions relates to iron limitation in the ocean. In recent years iron has become an important player when discussing ocean dynamics and nutrient cycles. The input of iron varies by region and is delivered to the ocean by dust (from dust storms) and is leached out of rocks. Iron is under consideration as the true limiting element in the ocean.Sony VAIO VPC-P111KX/G Battery

NH4+ and NO2 show a maximum concentration at 50-80 m (lower end of the euphotic zone) with decreasing concentration below that depth. This distribution can be accounted for by the fact that NO2 and NH4+ are intermediate species. They are both rapidly produced and consumed through the water column . Sony VAIO VPC-P111KX/P Battery

The amount of NH4+ in the ocean is about 3 orders of magnitude less than nitrate. Between NH4+, NO2, and NO3, NO2 has the fastest turnover rate. It can be produced during NO3assimilation, nitrification, and denitrification; however, it is immediately consumed again.Sony VAIO VPC-P111KX/W Battery

New vs. regenerated nitrogen

Nitrogen entering the euphotic zone is referred to as new nitrogen because it is newly arrived from outside the productive layer. The new nitrogen can come from below the euphotic zone or from outside sources. If the organic matter is eaten, respired, delivered to the water as ammonia, and re-incorporated into organic matter by phytoplankton it is considered recycled/regenerated production.Sony VAIO VPC-P112KX/B Battery


New production is an important component of the marine environment. One reason is that only continual input of new nitrogen can determine the total capacity of the ocean to produce a sustainable fish harvest. Harvesting fish from regenerated nitrogen areas will lead to a decrease in nitrogen and therefore a decrease in primary production. Sony VAIO VPC-P112KX/D Battery

This will have a negative effect on the system. However, if fish are harvested from areas of new nitrogen the nitrogen will be replenished.

Human influences on the nitrogen cycle

As a result of extensive cultivation of legumes (particularly soy, alfalfa, and clover), growing use of the Haber-Bosch process in the creation of chemical fertilizers, and pollution emitted by vehicles and industrial plants, human beings have more than doubled the annual transfer of nitrogen into biologically-available forms.Sony VAIO VPC-P112KX/G Battery

In addition, humans have significantly contributed to the transfer of nitrogen trace gases from Earth to the atmosphere, and from the land to aquatic systems. Human alterations to the global nitrogen cycle are most intense in developed countries and in Asia, where vehicle emissions and industrial agriculture are highest.Sony VAIO VPC-P112KX/P Battery

Nitrous oxide (N2O) has risen in the atmosphere as a result of agricultural fertilization, biomass burning, cattle and feedlots, and industrial sources. N2O has deleterious effects in the stratosphere, where it breaks down and acts as a catalyst in the destruction of atmospheric ozone. Sony VAIO VPC-P112KX/W Battery

In the atmosphere nitrous oxide is agreenhouse gas, and is currently the third largest contributor to global warming, after carbon dioxide and methane. While not as abundant in the atmosphere as carbon dioxide, it is for an equivalent mass, nearly 300 times more potent in its ability to warm the planet.Sony VAIO VPCP113KX/B Battery

Ammonia (NH3) in the atmosphere has tripled as the result of 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 (HNO3) that produces acid rain. Atmospheric ammonia and nitric acid damage respiratory systems.Sony VAIO VPC-P113KX/B Battery

All forms of high-temperature combustion have contributed to a 6 or 7 fold increase in the flux of NOx to the atmosphere. Its production is a function of combustion temperature - the higher the temperature, the more NOx is produced. Fossil fuel combustion is a primary contributor, but so are biofuels and even the burning of hydrogen.Sony VAIO VPCP113KX/D Battery

The higher combustion temperature of hydrogen produces more NOx than natural gas combustion. The very-high temperature of lightning produces small amounts of NOx, NH3, and HNO3.

Ammonia and nitrous oxides actively alter atmospheric chemistry. Sony VAIO VPC-P113KX/D Battery

They are precursors of tropospheric (lower atmosphere) ozone production, which contributes to smog, and acid rain, damages plants and increases nitrogen inputs to ecosystems. Ecosystem processes can increase with nitrogen fertilization, but anthropogenic input can also result in nitrogen saturation, which weakens productivity and can damage the health of plants, animals, fish, and humans.Sony VAIO VPCP113KX/G Battery

Decreases in biodiversity can also result if higher nitrogen availability increases nitrogen-demanding grasses, causing a degradation of nitrogen-poor, species diverse heathlands.

Wastewater treatment

Onsite sewage facilities such as septic tanks and holding tanks release large amounts of nitrogen into the environment by discharging through a drainfield into the ground.Sony VAIO VPC-P113KX/G Battery

Microbial activity consumes the nitrogen and other contaminants in the wastewater.

However, in certain areas, the soil is unsuitable and some or all of the wastewater, with the contaminants, enters the aquifers. These contaminants accumulate and eventually end up in drinking water. One of the contaminants most concerned about is nitrogen in the form of nitrates. Sony VAIO VPCP113KX/P Battery

A nitrate concentration of 10 ppm (parts per million) or 10 milligrams per liter is the current EPA limit for drinking water and typical household wastewater can produce a range of 20–85 ppm.

One health risk associated with drinking water (with >10 ppm nitrate) is the development of methemoglobinemia and has been found to cause blue baby syndrome. Sony VAIO VPC-P113KX/P Battery

Several American states have now started programs to introduce advanced wastewater treatment systems to the typical onsite sewage facilities. The result of these systems is an overall reduction of nitrogen, as well as other contaminants in the wastewater.

Environmental impacts

Additional risks posed by increased availability of inorganic nitrogen in aquatic ecosystems include water acidification; Sony VAIO VPCP113KX/W Battery

eutrophication of fresh and saltwater systems; and toxicity issues for animals, including humans. Eutrophication often leads to lower dissolved oxygen levels in the water column, including hypoxic and anoxic conditions, which can cause cause death of aquatic fauna.Sony VAIO VPC-P113KX/W Battery

Relatively sessile benthos, or bottom-dwelling creatures, are particularly vulnerable because of their lack of mobility, though large fish kills are not uncommon. Oceanic dead zones near the mouth of the Mississippi in the Gulf of Mexico are a well-known examples of algal bloom-induced hypoxia.Sony VAIO VPC-P114KX/B Battery

The New York Adirondack Lakes, Catskills, Hudson Highlands, Rensselaer Plateau and parts of Long Island display the impact of nitric acid rain deposition, resulting in the killing of fish and many other aquatic species. Sony VAIO VPC-P114KX/D Battery

Ammonia (NH3) is highly toxic to fish and the level of ammonia discharged from wastewater treatment facilities must be closely monitored. To prevent fish deaths, nitrification via aeration prior to discharge is often desirable. Land application can be an attractive alternative to the aeration.Sony VAIO VPC-P114KX/G Battery,Sony VAIO VPC-P114KX/P Battery,Sony VAIO VPC-P114KX/W Battery,Sony VAIO VPCP115JC Battery,Sony VAIO VPCP115JC/B Battery

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