Science Source

Temperature Decouples Ammonium and Nitrite Oxidation in Coastal Waters

Defines nitrification as a two-step process linking the reduced and oxidized sides of the nitrogen cycle; these steps are typically tightly coupled with the primary intermediate, nitrite, rarely accumulating in coastal environments
Experiments examining the response to temperature shifts of a nitrifying assemblage composed of the same organisms found in the field indicate that ammonia- and nitrite-oxidation become uncoupled between 20 and 30 °C, leading to nitrite accumulation
This suggests that nitrite peaks in coastal waters might be explained by differences in the responses of ammonia- and nitrite-oxidizers to increased summer temperatures
Analyzes field data from 270 stations in 29 temperate and subtropical estuaries and lagoons
Shows that transient accumulation of nitrite is driven primarily by water temperatures, rather than by hypoxia
Concludes that increased climate variability and warming coastal waters may therefore increase the frequency of these nitrite peaks, with potential ecosystem consequences that include increased N2O production, NO2– toxicity, and shifts in phytoplankton community composition