Fate of Ammonia: Overview, Diagram, Sources and Fate

Edited By Irshad Anwar | Updated on Jul 02, 2025 06:57 PM IST

Definition Of Ammonia

Another very important compound, composed of nitrogen and hydrogen combined in molecular form as NH₃, is ammonia. Its fate is important in assessments because it is part of the nitrogen cycle, acting in effect as the critical intermediate in transforming nitrogen into forms usable by plants and other organisms.

This Story also Contains

Definition Of Ammonia
Sources Of Ammonia
The Nitrogen Cycle And Ammonia
Fate Of Ammonia In Different Environments

Moreover, the application of ammonia in agriculture as a fertilizer and its impact on environmental health—through eutrophication and atmospheric pollution—make studies on this molecule very essential. This paper will present a summary of the production of ammonia, its transformation in different ecosystems, and the environmental implications of its presence and movement.

Sources Of Ammonia

Ammonia is produced from the following sources:

Natural Sources

Decomposition of organic matter

This occurs in the natural decaying of plants and remains of animals that emit ammonia into the soil.

Animal waste

Excretes from domestic and wild animals excrete quite large amounts of ammonia to the environment.

Anthropogenic Sources

Agricultural activities

Application of nitrogen-based fertilizers and rearing animals leads to the emission of ammonia.

Industrial processes

The manufacturing processes of numerous chemicals, like fertilizers and plastics, emit ammonia.

Wastewater treatment

Wastewater from sewage and industrial waste results in the production of ammonia.

The Nitrogen Cycle And Ammonia

The nitrogen cycle is the process through which nitrogen is transformed from one of its chemical forms to another. This is a change that holds a significant value to the existence of life on this Earth.

Role Of Ammonia In The Nitrogen Cycle

An important intermediate in the nitrogen cycle is formed by the decay of organic matter. This is also the starting substance for several conversion processes

Conversion Processes Involving Ammonia

Nitrification: Ammonia gets oxidized to nitrites and then to nitrates, that too by the nitrifying bacteria, hence making nitrogen available to plants in a usable form.

Ammonification: It is the conversion of organic nitrogen into ammonia, done by decomposers like bacteria and fungi. This replaces the amount of ammonia in the soil and hence continues the cycle of nitrogen.

Fate Of Ammonia In Different Environments

The effect on ammonia varies based on the type of environment:

Soil Environment

All ammonia can potentially bind to soil particles therefore making the ammonium less available for uptake by plants but more stable in the soil
Soil microorganisms convert through oxidation the ammonia into nitrites and nitrates- plant-absorbable forms.
These nitrates turn over and get again reduced into nitrogen gas through denitrification and released into the atmosphere.

Aquatic Environment

Ammonia is easily soluble in water; hence, its concentration and bioavailability will vary in aquatic systems.
Ammonia can easily and readily be absorbed by aquatic plants and microorganisms.
It can readily provide the much-needed Nutrition that the said organisms can easily utilise.
On the contrary, large doses of ammonia represent lethal doses to fish and other forms of aquatic life.
Ammonia is reduced to nitrite and nitrate through microbial action the same as that in soil, and all these processes are of equal importance in the aquatic nitrogen cycle.

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Atmospheric Environment

The ammonia can be volatilised in the atmosphere, mainly from soil and water under high temperatures and alkaline conditions.
In the atmosphere itself, ammonia can react with acids to form ammonium salts, which affect air quality and atmospheric chemistry.
Through precipitation or any other kind of dry deposition, O-ammonia and other derivative products get re-deposited back to the earth's surface and finally find their way into the earth's soil and water systems to enter into the cycle of nitrogen again.

Frequently Asked Questions (FAQs)

1. What is the fate of ammonia in the environment?

The ammonia changes into other nitrogen compounds, like nitrate and nitrite, by different chemical and biological reactions of concern for the quality of the soil, water, and air.

2. How does ammonia affect the nitrogen cycle?

Ammonia is but one extremely important factor in the nitrogen cycle having roles in nitrification and ammonification processes as a basis for a proper balance in ecosystems.

3. What are the sources of ammonia emissions?

Natural sources of ammonia emissions include the variety associated with organic matter and decomposition of dung, while anthropogenic sources include those dealing with agriculture, industries, and wastewater treatment.

4. What are the health effects of ammonia exposure?

Respiratory and skin problems are just some serious health hazards that could be caused by ammonia exposure at higher concentrations, with the ensuing serious conditions determined by the length of time exposed.

5. How can ammonia emissions be controlled?

Control of the emission of ammonia can be ensured by better agricultural practices, industrial emission controls, efficient treatment of wastewater, and rigorous enforcement of environment-related laws and regulations.

6. What is ammonia and why is it important in plant biology?

Ammonia (NH3) is a nitrogen-containing compound that plays a crucial role in plant biology. It's important because it's the primary form of nitrogen that plants can directly assimilate into amino acids and other organic compounds. Plants need nitrogen for growth, protein synthesis, and overall metabolism.

7. What is the difference between ammonium (NH4+) and ammonia (NH3) in terms of plant uptake?

Ammonium (NH4+) is the ionic form of ammonia (NH3). Plants primarily take up nitrogen in the form of ammonium rather than ammonia. Ammonium is positively charged and water-soluble, making it easier for plants to absorb through their roots. Ammonia, being a gas, can be toxic and is not typically absorbed directly. The balance between NH4+ and NH3 in the soil depends on pH, with more NH4+ at lower pH levels.

8. What is the role of ammonium transporters in plants?

Ammonium transporters are membrane proteins that facilitate the uptake of ammonium (NH4+) into plant cells. They play crucial roles in:

9. How do plants transport ammonia within their tissues?

Plants primarily transport nitrogen in organic forms rather than as free ammonia. After assimilation, nitrogen is often transported as amino acids (especially glutamine and asparagine) or amides through the xylem and phloem. Some plants can transport small amounts of ammonium ions, but this is carefully regulated to prevent toxicity.

10. What happens if a plant accumulates too much ammonia?

If a plant accumulates too much ammonia, it can lead to toxicity symptoms. These may include leaf chlorosis (yellowing), stunted growth, and in severe cases, cell death. Excess ammonia can disrupt cellular pH, interfere with photosynthesis, and cause oxidative stress. Plants have evolved various mechanisms to prevent this, including rapid assimilation and compartmentalization.

11. What is the "fate of ammonia" in plants?

The "fate of ammonia" refers to what happens to ammonia once it's inside the plant. Generally, it's quickly incorporated into organic compounds to prevent toxicity. The main fates are: 1) Assimilation into amino acids, 2) Storage in vacuoles, 3) Transport to other parts of the plant, and 4) In some cases, loss through volatilization.

12. Why can't plants store large amounts of free ammonia?

Plants can't store large amounts of free ammonia because it's toxic at high concentrations. Ammonia can disrupt pH balance, interfere with electron transport in photosynthesis, and damage cellular membranes. Therefore, plants rapidly convert ammonia into non-toxic organic compounds.

13. What is the primary enzyme responsible for ammonia assimilation in plants?

The primary enzyme responsible for ammonia assimilation in plants is glutamine synthetase (GS). This enzyme catalyzes the ATP-dependent condensation of ammonia with glutamate to form glutamine, which is the first step in incorporating nitrogen into organic compounds.

14. How does the GS-GOGAT cycle work in ammonia assimilation?

The GS-GOGAT cycle involves two main enzymes: Glutamine Synthetase (GS) and Glutamate Synthase (GOGAT). GS combines ammonia with glutamate to form glutamine. GOGAT then transfers the amide group from glutamine to α-ketoglutarate, forming two molecules of glutamate. One glutamate is used to continue the cycle, while the other is used for other biosynthetic processes.

15. What role do plant roots play in ammonia acquisition?

Plant roots play a crucial role in ammonia acquisition by: 1) Directly absorbing ammonium ions from the soil, 2) Providing a habitat for nitrogen-fixing bacteria in legumes, 3) Absorbing nitrates which can be reduced to ammonia, and 4) Secreting compounds that influence soil microbial activity and nitrogen availability.

16. What is photorespiration and how does it relate to ammonia production in plants?

Photorespiration is a process that occurs in C3 plants when the enzyme RuBisCO fixes oxygen instead of carbon dioxide. This process produces toxic glycolate, which is converted to glycine in peroxisomes. When two glycine molecules are converted to serine in mitochondria, ammonia is released as a byproduct, contributing to the plant's internal ammonia pool.

17. What is the role of nitrite reductase in ammonia production?

Nitrite reductase is an enzyme that catalyzes the reduction of nitrite (NO2-) to ammonia (NH3). This is part of the nitrate assimilation pathway in plants. After nitrate is reduced to nitrite by nitrate reductase, nitrite reductase completes the process by converting nitrite to ammonia. This ammonia can then be assimilated into organic compounds through the GS-GOGAT cycle.

18. What is the significance of ureides in nitrogen transport for some plants?

Ureides, such as allantoin and allantoic acid, are important nitrogen transport compounds in some plants, particularly in tropical legumes. They have a high nitrogen-to-carbon ratio, making them efficient for nitrogen transport. Ureides are produced in root nodules after nitrogen fixation and are transported through the xylem to shoots, where they are broken down to release ammonia for assimilation.

19. How does salt stress affect ammonia metabolism in plants?

Salt stress can significantly impact ammonia metabolism in plants. It can: 1) Reduce nitrogen uptake from the soil, 2) Interfere with the activity of enzymes involved in ammonia assimilation, 3) Cause accumulation of toxic levels of ammonia due to protein breakdown, 4) Alter the balance between ammonium and nitrate uptake, and 5) Affect the transport of nitrogenous compounds within the plant.

20. How do C3, C4, and CAM plants differ in their ammonia metabolism?

C3, C4, and CAM plants have differences in their ammonia metabolism:

21. How do plants typically acquire ammonia?

Plants acquire ammonia through several methods: 1) Direct absorption of ammonium ions (NH4+) from the soil, 2) Reduction of nitrates (NO3-) absorbed from the soil into ammonia, 3) Nitrogen fixation by symbiotic bacteria in root nodules of legumes, and 4) Recycling of ammonia from protein breakdown within the plant.

22. How do legumes differ from other plants in terms of ammonia acquisition?

Legumes have a unique ability to form symbiotic relationships with nitrogen-fixing bacteria (rhizobia) in their root nodules. These bacteria can convert atmospheric nitrogen (N2) into ammonia, which the plant can then use. This gives legumes an advantage in nitrogen-poor soils.

23. What is the role of glutamine in ammonia metabolism?

Glutamine plays a central role in ammonia metabolism in plants. It's the primary product of ammonia assimilation by glutamine synthetase. Glutamine serves as a nitrogen donor for the synthesis of other amino acids and nucleotides. It's also a key compound for nitrogen storage and transport within the plant.

24. What is ammonia volatilization and why is it a concern for plants?

Ammonia volatilization is the process by which ammonia gas is released from plant tissues into the atmosphere. It's a concern because it represents a loss of valuable nitrogen from the plant. This can occur when ammonia accumulates faster than it can be assimilated, often due to stress conditions or in plants with high nitrogen content.

25. How do plants handle ammonia produced during protein catabolism?

When proteins are broken down (catabolized), ammonia is released. Plants handle this by: 1) Reassimilating the ammonia through the GS-GOGAT cycle, 2) Incorporating it into transport amino acids like glutamine and asparagine, 3) In some cases, storing it temporarily in vacuoles, and 4) Using it for the synthesis of new proteins or other nitrogen-containing compounds.

26. What is the connection between carbon metabolism and ammonia assimilation in plants?

Carbon metabolism and ammonia assimilation are closely linked in plants. The assimilation of ammonia into amino acids requires carbon skeletons, which are provided by the carbon metabolism pathways. For example, α-ketoglutarate from the citric acid cycle is used in the GS-GOGAT cycle. Additionally, both processes compete for energy (ATP) and reducing power (NADPH).

27. How do plants regulate ammonia assimilation?

Plants regulate ammonia assimilation through several mechanisms: 1) Controlling the expression and activity of key enzymes like glutamine synthetase, 2) Adjusting the uptake of nitrogen from the soil, 3) Modulating the transport of nitrogenous compounds within the plant, 4) Responding to the carbon/nitrogen balance, and 5) Hormonal control, particularly by cytokinins.

28. What is the role of asparagine in ammonia metabolism?

Asparagine plays an important role in ammonia metabolism as a nitrogen storage and transport compound. It has a high N:C ratio, making it efficient for nitrogen storage. Asparagine is often synthesized when there's excess ammonia or during periods of stress. It can be easily transported through the xylem and stored in vacuoles without causing toxicity.

29. How do environmental factors affect ammonia assimilation in plants?

Environmental factors greatly influence ammonia assimilation. Light availability affects the energy supply for assimilation. Temperature impacts enzyme activity. Soil pH influences the form of nitrogen available (ammonium or nitrate). Drought stress can reduce nitrogen uptake and assimilation. Nutrient availability, especially of elements needed for enzyme cofactors, also plays a role.

30. How do aquatic plants handle ammonia differently from terrestrial plants?

Aquatic plants often have a higher tolerance for ammonia than terrestrial plants. They can absorb ammonium directly from the water through their leaves as well as their roots. Some aquatic plants have specialized structures for ammonia uptake and can use ammonia as their primary nitrogen source, whereas most terrestrial plants prefer nitrate.

31. How does nitrogen deficiency affect ammonia metabolism in plants?

Under nitrogen deficiency, plants alter their ammonia metabolism in several ways: 1) They increase the efficiency of nitrogen uptake and assimilation, 2) They may increase the expression of high-affinity ammonium transporters, 3) They often reallocate nitrogen from older to younger tissues, 4) They may increase the activity of enzymes involved in nitrogen assimilation, and 5) They may reduce overall growth to conserve nitrogen.

32. How do plants detoxify ammonia?

Plants detoxify ammonia primarily through rapid assimilation into organic compounds. The main strategies include: 1) Quick incorporation into glutamine via glutamine synthetase, 2) Conversion to other amino acids and amides, 3) Temporary storage in vacuoles (in some species), 4) Transport to other parts of the plant for assimilation or storage, and 5) In extreme cases, volatilization through leaves.

33. What is the role of mycorrhizal fungi in plant ammonia acquisition?

Mycorrhizal fungi form symbiotic relationships with plant roots and play a significant role in ammonia acquisition. They can: 1) Increase the surface area for nutrient absorption, 2) Access nitrogen sources that are unavailable to plant roots, 3) Convert organic nitrogen to ammonium, making it available to plants, 4) In some cases, directly transfer ammonium to plant roots, and 5) Improve overall plant nitrogen status, indirectly affecting ammonia metabolism.

34. How does the presence of other ions in the soil affect ammonium uptake by plants?

The presence of other ions in the soil can significantly affect ammonium uptake:

35. How does ammonia assimilation differ between roots and leaves?

Ammonia assimilation differs between roots and leaves in several ways:

36. What is the relationship between ammonia metabolism and amino acid biosynthesis?

Ammonia metabolism and amino acid biosynthesis are closely interlinked:

37. How do plants cope with ammonia toxicity in waterlogged soils?

In waterlogged soils, where ammonia can accumulate, plants cope through several mechanisms:

38. What is the role of glutamate dehydrogenase (GDH) in plant ammonia metabolism?

Glutamate dehydrogenase (GDH) plays a complex role in plant ammonia metabolism:

39. How does nitrogen fertilization affect plant ammonia metabolism?

Nitrogen fertilization can significantly impact plant ammonia metabolism: