Nitrate (NO3-) forms in water when bacteria use dissolved oxygen to oxidize ammonium. Nitrate is mobile and may seep into streams, lakes and estuaries from ground water enriched by animal or human wastes or commercial fertilizers. High concentrations of nitrate can enhance the growth of algae and aquatic plants.
The YSI nitrate sensor consists of a silver/silver chloride wire electrode in a custom filling solution. The internal solution is separated from the sample medium by a polymer membrane, which selectively interacts with nitrate ions.