The formation of NH 3 is favoured at higher pHs but is also affected by temperature. This means that while the concentration of total ammonia may remain constant in a water body, the proportion of un-ionized ammonia fluctuates with temperature and pH. Significant formation of NH 3 can occur within a single day as water temperatures fluctuate. In 1996, ammonia was ranked first by the National Pollutant Release Inventory in terms of amounts released by industry to the Canadian environment. Ammonia is also a naturally occurring compound required by most organisms for protein synthesis and a waste product of animal, fish and microbial metabolism. The primary human use of ammonia is as a nitrogen source in fertilizers, especially anhydrous ammonia and urea.
Ammonia is released into the environment by many industries and other human activities.
Negative environmental impacts on some aquatic ecosystems are occurring from this source. Agricultural releases of ammonia to water cannot be quantified because of the diffuse nature of agriculture in Canada and the difficulty in quantifying such releases. The major industries are pulp and paper mills, mines, food processing and fertilizer production. Through modelling and measuring ammonia deposition in areas influenced by agricultural emissions and studying the situation in Europe, it was determined that some areas of Canada, like the Lower Fraser Valley, are potential impact regions. It was determined from reviewing toxicity and exposure data that freshwater organisms are most at risk from releases of ammonia in the aquatic environment.