High Nitrite Levels off Northern Peru: A Signal of Instability in the Marine Denitrification Rate

During February and March 1985, nitrite levels along the northern (approximately 7° to 10°S) Peruvian coast were unusually high. These accumulations occurred in oxygen-deficient waters, suggesting intensified denitrification. In a shallow offshore nitrite maximum, concentrations were as high as 23 micromoles per liter (a record high). Causes for the unusual conditions may include a cold anomaly that followed the 1982-83 El Nino. The removal of combined nitrogen (approximately 3 to 10 trillion grams of nitrogen per year) within zones of new or enhanced denitrification observed between 7° to 16°S suggests a significant increase in oceanic denitrification.