A method of measuring the ammonia nitrogen concentration of a water body

Abstract

The invention belongs to the technical field of water quality monitoring, and relates to a method of measuring the ammonia nitrogen concentration of a water body. The method includes a step of preparatory work, a step of mapping an ammonia nitrogen standard curve, a step of mapping nitrite nitrogen standard curve, a step of mapping a curve of influences of nitrite nitrogen concentrations on ammonia nitrogen measurement absolute errors and a step of measuring the ammonia nitrogen concentration, which are five steps. Wider-range ammonia nitrogen and nitrite nitrogen concentrations in a high-salinity water body can be measured. Hypobromite oxidation time is shortened from 30 min to 10 min. Hydrochloric acid is adopted in place of phosphoric acid for a nitrite nitrogen color developing agent, thus reducing pollution. A hydrochloric acid solution of sulfanilamide and an aqueous solution of N-(1-naphthyl)ethylenediamine dihydrochloride are mixed, and therefore nitrite nitrogen concentration measuring steps are simplified. The upper limit of nitrite nitrogen concentration measurement is increased to a value that is three or more times of the upper limit in the national standard method in China. In a nitrite nitrogen concentration range of 0-0.75 mg / L, accuracy of measurement of ammonia nitrogen concentrations in a range of 0-1.25 mg / L is good. The method has characteristics of a simple process, reliable principles, short operation time, environment protection, energy conservation, a low economic cost, high operationality and high measurement result accuracy.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of water quality monitoring, and in particular relates to a method for measuring the ammonia nitrogen value in a water body. On the premise of eliminating the interference of nitrite nitrogen (nitrite nitrogen), the upper limit value for the determination of the ammonia nitrogen concentration in the water body is improved, and at the same time the The upper limit of the determination of nitrite nitrogen concentration is used in water purification, aquatic animal and plant cultivation and breeding and other occasions. [0003] Background technique: [0004] Ammonia nitrogen refers to the free ammonia (NH 3 ) and ammonium ions (NH 4 +) The nitrogen in the form of nitrogen mainly comes from the decomposition of organic nitrogen and the reduction of nitrate nitrogen and nitrite nitrogen. Ammonia nitrogen has a great impact on human health and the ecological environment: ammonia nitrogen in water is conve...

AI Technical Summary

Problems solved by technology

[0004] Ammonia nitrogen refers to the free ammonia (NH 3 ) and ammonium ions (NH 4 +) The nitrogen in the form of nitrogen mainly comes from the decomposition of organic nitrogen and the reduction of nitrate nitrogen and nitrite nitrogen. Ammonia nitrogen has a great impact on human health and the ecological environment: ammonia nitrogen in water is converted into nitrite under certain conditions. Drinking, nitrite will combine with protein to form strong carcinogenic nitrosamines, which is extremely harmful to human health; the harm of ammonia nitrogen to aquatic organisms mainly includes reduced food intake, slowed growth, tissue damage, reduced oxygen transport between tissues, It can lead to hyperactivity of aquatic organisms, loss of balance in the water, convulsions, and even death in severe cases. The fish among them are sensitive to ammonia nitrogen. When the ammonia nitrogen content is high, the fish will die; ammonia nitrogen is very polluting to the marine environment. Can not be ignored; Therefore, the ammonia nitrogen concentration value is one of the important water quality monitoring indicators of close attention in aquaculture nursery and culture, and the mensuration of the ammonia nitrogen concentration in the mariculture water body is the important foundation of mariculture production management and scientific research work; In the prior art, The methods for determining the concentration of ammonia nitrogen mainly include Nessler's reagent colorimetric method, ion chromatography, gas phase molecular absorption method, indophenol blue spectrophotometry and hypobromite oxidation method, wherein Nessler's reagent colorimetric method utilizes mercuric iodide and The alkaline solution of potassium iodide reacts with ammonia to form a light reddish brown colloidal compound. The chromaticity is proportional to the concentration of ammonia nitrogen. The concentration of ammonia nitrogen is calculated after measuring the absorbance in the wavelength range of 410-425nm. However, due to the large amount of calcium and Magnesium ions, while calcium and magnesium ions react with Nessler's reagent, resulting in turbidity of the water sample, which interferes with the determination accuracy of the ammonia nitrogen concentration value, and is not suitable for the determination of the ammonia nitrogen concentration value in seawater; the ion chromatography and gas phase molecular absorption method used The measuring instrument has the problems of high purchase price and high maintenance cost, which is not convenient for popularization and use; the indophenol blue spectrophotometric method has a long reaction time and is not suitable for the rapid determination of ammonia nitrogen value in seawater, and its use is limited; the hypobromite oxidation method There is no highly toxic substance in the determination process, and the determination is fast and convenient. In the national standard, the total concentration of ammonia nitrogen and nitrite nitrogen is measured by the hypobromite oxidation method, and then the concentration of nitrite nitrogen is deducted to obtain the determination result of ammonia nitrogen. Experiments have confirmed that in the presence of nitrite nitrogen, when using the hypobromite oxidation method to measure the ammonia nitrogen value of water, the measured value of ammonia nitrogen is quite different from the actual value, and there is a non-negligible error, even in the presence of lower concentrations of nitrite nitrogen In the case of nitrite nitrogen, there are still non-negligible errors. The higher the concentration of nitrite nitrogen, the greater the difference between the measured value and the actual value of ammonia nitrogen concentration, and the concentration of nitrite nitrogen is linearly positively correlated with the absolute error of ammonia nitrogen concentration measurement; Therefore, in water bodies where nitrite nitrogen exists, it is difficult to accurately measure the concentration of ammonia nitrogen in seawater with the traditional national standard method. At present, there is no accurate, economical and efficient method for determining the concentration of ammonia nitrogen in seawater.

Images