Effects of salinity on nitrification in the East River

The rates of nitrification in water samples obtained from different locations of the East River in New York, N.Y., from December 1971 to March 1972 were determined. The oxidation of ammonium to nitrite and of nitrite to nitrate could be increased by diluting the water with freshwater nutrient media. The rates of nitrification in the water of the inner part of the East River were higher than those in the water toward New York Harbor and Long Island Sound. Salinity was one main factor responsible for the inhibition of nitrification. Pure cultures of nitrifying bacteria isolated from the river water showed varying degrees of NaCl tolerance.