What does ammonia nitrogen refer to in water quality testing (what is the testing standard for ammonia nitrogen in water quality)

Ammonia nitrogen refers to nitrogen that exists in the form of free ammonia (NH3) and ammonium ions (NH4+) in water. The reason why we pay so much attention to the ammonia nitrogen index in water is that the level of ammonia nitrogen in the water body has a significant positive correlation with the eutrophication of the water body, and Ammonia nitrogen in drinking water can be converted into nitrite under certain conditions. If you drink it for a long time, the nitrite in the water will combine with protein to form nitrosamine, which is a strong carcinogen and is extremely harmful to human health.

In 2020, the amount of ammonia nitrogen discharged from wastewater nationwide was 984,000 tons. Among them, ammonia nitrogen emissions from industrial sources were 21,000 tons, accounting for 2.2% of the national ammonia nitrogen emissions; ammonia nitrogen emissions from agricultural sources were 254,000 tons, accounting for 25.8% of the national ammonia nitrogen emissions; ammonia nitrogen emissions from living sources were 707,000 tons, It accounts for 71.8% of the national ammonia nitrogen discharge; the ammonia nitrogen discharge in the wastewater (including leachate) of centralized pollution control facilities is 2,000 tons, accounting for 0.2% of the national ammonia nitrogen discharge.

What is the standard for ammonia nitrogen testing in water quality?

1. 'HJ 535-2009 Water Quality Determination of Ammonia Nitrogen Nessler Reagent Spectrophotometry'

Principle: Ammonia nitrogen in the form of free ammonia or ammonium ions reacts with Nessler reagent to form a light reddish-brown complex. The absorbance of the complex is proportional to the content of ammonia nitrogen. The absorbance is measured at a wavelength of 420nm. It is suitable for the detection of ammonia nitrogen content in surface water, groundwater, domestic sewage and industrial wastewater.

2. 'HJ 536-2009 Water Quality Determination of Ammonia Nitrogen Salicylic Acid Spectrophotometry'

Principle: In the presence of an alkaline medium (pH = 11.7) and sodium nitroferricyanide, ammonia and ammonium ions in water react with salicylate and hypochlorite ions to form blue compounds, which are spectrophotometrically measured at 697nm. meter to measure absorbance. It is suitable for the detection of ammonia nitrogen content in groundwater, surface water, domestic sewage and industrial wastewater.