Un-ionized ammonia

What is Un-ionized ammonia?

Un-ionized ammonia meaning The neutral form of ammonia-nitrogen in water, usually occurring as NH4OH. Un-ionized ammonia is the principal form of ammonia that is toxic to aquatic life. The relative proportion of un-ionized to ionized ammonia (NH4+) is controlled by water temperature and pH. At temperatures and pH values typical of most natural waters, the ionized form is dominant.

 

reference: USGS – National Water-Quality Assessment (NAWQA) Project