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2022-11-2314:10 Anhui
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Text: Medsch technology
Total nitrogen, TN for short, and total nitrogen content in water is one of the important indexes to measure water quality.
The definition of total nitrogen is the total amount of inorganic nitrogen and organic nitrogen in water. Include inorganic nitrogen such as NO3, NO2 and NH4, and organic nitrogen such as protein, amino acids and organic amines, calculated in milligrams of nitrogen per liter of water. It is often used to indicate the pollution degree of nutrients to water.
Ammonia nitrogen refers to nitrogen in the form of free ammonia (NH3) and ammonium ion (NH4+) in water. The nitrogen content of animal organic matter is generally higher than that of plant organic matter. At the same time, the nitrogen-containing organic matter in human and animal feces is unstable and easily decomposed into ammonia. Therefore, when the content of ammonia nitrogen in water increases, it refers to the combined nitrogen in the form of ammonia or ammonium ions.
Nitrate nitrogen (NO3) is the main component in surface water and groundwater. Ammonia nitrogen in the form of free ammonia (NH3) and ammonium ion (NH4+) in nitrogen-polluted water is called hydrated ammonia, also known as nonionic ammonia. Non-ionic ammonia is the main factor causing toxicity of aquatic organisms, while ammonium ion is relatively basically non-toxic. The concentration of nonionic ammonia in Class III surface water is ≤0.02 mg/L. Ammonia nitrogen is a nutrient in water, which can lead to eutrophication, is the main oxygen-consuming pollutant in water, and is toxic to fish and some aquatic organisms.
Total nitrogen is not the same as ammonia nitrogen. Total nitrogen is all nitrogen in water, including organic and inorganic, and ammonia nitrogen is nitrogen existing in the state of ammonia free radical or free ammonia.
Total nitrogen contains ammonia nitrogen. Total nitrogen is now generally determined by ultraviolet spectrophotometry.
Ammonia nitrogen is generally measured by Nessler photometry or salicylic acid method, using visible light.
Theoretically, total nitrogen = ammonia nitrogen+nitrite nitrogen+nitrate nitrogen+organic nitrogen. Ammonia nitrogen = kjeldahl nitrogen-organic nitrogen. Ammonia nitrogen+nitrite+nitrate nitrogen