Ammonia Nitrogen In Water: Understanding The Causes Of Pollution

Ammonia is a colourless, strong-smelling gas that is highly soluble in water. It is toxic to aquatic life and can cause direct harm to aquatic ecosystems. Ammonia is produced for commercial fertilizers and other industrial applications, and can enter aquatic environments through municipal effluent discharges, animal waste, nitrogen fixation, air deposition, and runoff from agricultural lands. Natural sources of ammonia include the decomposition of organic waste matter, gas exchange with the atmosphere, forest fires, and animal and human waste. The increasing levels of ammonia in water have adverse effects on aquatic life and human health.

Characteristics and Values of Ammonia Nitrogen Pollution in Water

Natural sources of ammonia include the decomposition of organic waste matter

Ammonia is one of several forms of nitrogen that exist in aquatic environments. Unlike other forms of nitrogen, ammonia can have direct toxic effects on aquatic life. Natural sources of ammonia include the decomposition or breakdown of organic waste matter.

The decomposition of organic waste matter occurs through both aerobic and anaerobic processes. Aerobic decomposition requires a significant amount of oxygen and does not produce the unpleasant odours associated with anaerobic decomposition. In both cases, microorganisms break down organic waste and use nitrogen, phosphorus, and other nutrients to live and develop cell protoplasm. However, they reduce organic nitrogen to organic acids and ammonia.

Anaerobic decomposition occurs in environments where oxygen is absent, such as in the organic muds at the bottom of marshes or in buried organic materials. This process is slower and less efficient than aerobic decomposition. It is characterised by the production of disagreeable odours, such as hydrogen sulfide and reduced organic compounds containing sulfur, known as mercaptans.

The decomposition of organic waste matter, especially in anaerobic conditions, can lead to the formation of ammonia. This process is a significant contributor to ammonia pollution in aquatic environments. The ammonia produced through the decomposition of organic waste can accumulate in sediments and leach into the water, posing toxic effects on aquatic organisms.

In addition to natural sources, ammonia pollution in water can also be attributed to various human activities. These include municipal effluent discharges, animal waste, agricultural runoff, and industrial processes that release ammonia as a byproduct. The increase in ammonia concentrations in water can have detrimental effects on aquatic ecosystems, including fish kills and negative impacts on fish growth, gill condition, and organ weights.

Municipal effluent discharges and animal waste are direct contributors to ammonia in water

Ammonia is one of the forms of nitrogen that exist in aquatic environments. Unlike other forms of nitrogen, ammonia can directly harm aquatic life. It is produced for commercial fertilizers and other industrial applications. Natural sources of ammonia include the decomposition or breakdown of organic waste matter, gas exchange with the atmosphere, forest fires, animal and human waste, and nitrogen fixation processes.

Municipal effluent discharges and animal waste are direct contributors to the presence of ammonia in water. Municipal waste treatment plants and publicly owned treatment works (POTWs) process domestic waste and operate within permit limits designed to protect receiving water bodies from excess inputs of pollutants. However, municipal wastewater treatment plants have been shown to discharge high levels of ammonia into freshwater bodies.

Animal waste, including manure and urine, is a primary source of ammonia emissions. The conversion of feed to animal products is often inefficient, with 50-80% of the nitrogen in the feed being excreted in animal waste. Ammonia is generated due to the nitrogen in the feces and urine of pigs and cattle and the uric acid in poultry manure. Ammonia is formed from the biological and chemical breakdown of manure protein, uric acid, and urea during manure storage and decomposition.

Agricultural activities, livestock, and poultry farming are significant contributors to ammonia emissions. Among these sectors, dairy and beef cattle production contribute about 54% of total ammonia emissions, poultry production contributes 33%, and swine production contributes 12%. Ammonia emissions from animal waste operations can cause soil acidification and eutrophication of surface water.

To address the issue of ammonia in water, various methods have been explored to remove ammonia nitrogen from municipal waste treatment effluents, including the use of natural minerals and sorbents. The activation process involves mixing natural sorbents with aqueous solutions of sodium chloride, and the suspension is then stirred, filtered, and washed with distilled water. The wet material is dried, and the NH4+ adsorption capacity and removal efficiency are calculated.

Nitrogen fixation, air deposition, and agricultural runoff are indirect causes

Nitrogen Fixation

Nitrogen fixation is a microbially-driven process that plays a critical role in the fate of nitrogen in Earth's ecosystems. It is responsible for converting nitrogen into a form that can be used by plants and other microorganisms for growth. While nitrogen fixation is essential for sustaining life, human activities have significantly altered the global nitrogen cycle, leading to unintended consequences. For example, the excessive use of nitrogen-based fertilizers in agriculture can result in nitrogen runoff into nearby water bodies, contributing to ammonia nitrogen pollution.

Air Deposition

Air deposition, or atmospheric deposition, is another significant indirect cause of ammonia nitrogen pollution in water. This occurs when nitrogen compounds, such as ammonia and nitrogen oxides, are released into the atmosphere and subsequently deposited into water bodies. The sources of these nitrogen compounds can be natural, such as chemical reactions and fossil fuel combustion, or anthropogenic, including motor vehicles, energy production, and agricultural emissions. Once deposited in water, these nitrogen compounds can cause ecological imbalances and harm aquatic life.

Agricultural Runoff

Agricultural practices are a major contributor to ammonia nitrogen pollution in water through runoff. Farmers apply chemical fertilizers and animal manure to their fields to provide crops with the necessary nitrogen and phosphorus for growth. However, when these nutrients are not fully utilized by the plants, they can be washed away from the fields during rainfall or snowmelt events, leading to nutrient-rich runoff. This runoff carries excess nitrogen into nearby waterways, increasing the risk of eutrophication, harmful algal blooms, and adverse effects on aquatic ecosystems and human health.

To mitigate the impact of agricultural runoff, farmers can implement conservation tillage practices, which involve reducing the frequency and intensity of tilling. This helps improve soil health, reduce erosion, and minimize the chances of nutrients reaching waterways. Additionally, managing livestock access to streams and engaging in watershed efforts can further reduce nutrient pollution from agricultural sources.

Ammonia in water is toxic to aquatic life, causing tissue and blood damage

Ammonia is a colourless, pungent-smelling gas that dissolves in water to form ammonium hydroxide solution. It is produced for commercial fertilizers and other industrial applications. Natural sources of ammonia include the decomposition or breakdown of organic waste matter, gas exchange with the atmosphere, forest fires, animal and human waste, and nitrogen fixation processes.

Ammonia is toxic to aquatic life, causing tissue and blood damage. It is one of several forms of nitrogen that exist in aquatic environments. Unlike other forms of nitrogen, which can cause nutrient over-enrichment of a body of water at elevated concentrations and indirect effects on aquatic life, ammonia causes direct toxic effects on aquatic life. When ammonia is present in water at high enough levels, it is difficult for aquatic organisms to sufficiently excrete the toxicant, leading to toxic buildup in internal tissues and blood. This buildup can cause internal organ damage, nervous system dysfunction, and impaired respiration.

Environmental factors, such as pH and temperature, can affect ammonia toxicity to aquatic animals. Unionized ammonia (NH3) is very toxic to aquatic animals, particularly fish, because it can readily diffuse across gill membranes. Ionized ammonia does not pass as easily through gill membranes, so it is significantly less toxic than the unionized form. In most fish, ammonia is excreted by passive diffusion of ammonia across the gills according to its partial pressure gradient. Disruption of this gradient causes internal ammonia concentrations to increase, affecting internal organs, nervous system function, and respiration.

Sources associated with agriculture, urbanization, industry, and aquaculture can directly increase ammonia inputs to aquatic systems via four main transport pathways: stormwater runoff, leakage or leachate into groundwater sources, atmospheric emissions and deposition, or direct effluent discharges. Ammonia is a key component of the nitrogen cycle in streams, where it may be dissolved in the water column or associated with sediments. At high enough concentrations, ammonia can be toxic to aquatic organisms.

Human health is also at risk from the adverse effects of ammonia in water

Ammonia (NH3) is a colourless gas with a pungent, suffocating odour. It is one of the most commonly produced industrial chemicals in the United States, used in agriculture as fertilizer, as well as in water purification and the manufacture of plastics, explosives, textiles, pesticides, dyes, and other chemicals. Natural sources of ammonia include the decomposition of organic waste matter, gas exchange with the atmosphere, forest fires, animal and human waste, and nitrogen fixation processes.

Ammonia is toxic to both humans and aquatic life. Human health is also at risk from the adverse effects of ammonia in water. Most people are exposed to ammonia through inhalation of the gas or vapours. Exposure to high concentrations of ammonia in the air causes immediate burning of the nose, throat, and respiratory tract, leading to bronchiolar and alveolar edema, and airway destruction resulting in respiratory distress or failure. Inhalation of lower concentrations can cause coughing, and nose and throat irritation.

Ammonia interacts with moisture in the skin, eyes, oral cavity, respiratory tract, and mucous surfaces to form the caustic ammonium hydroxide, which causes the destruction of cells and tissues. Ingesting ammonia causes similar corrosive effects and requires immediate decontamination and treatment. There is no antidote for ammonia poisoning, but most people recover with treatment.

Ammonia can enter the aquatic environment through direct means, such as municipal effluent discharges and the excretion of nitrogenous wastes from animals, and indirect means such as nitrogen fixation, air deposition, and runoff from agricultural lands. When present in water at high enough levels, ammonia is toxic to aquatic organisms, causing a toxic buildup in internal tissues and blood, potentially leading to death.

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