9530187 MONTOYA Denitrification (=respiration of oxidized nitrogen to dinitrogen gas) results in the loss, from the biosphere, of combined nitrogen, a critical nutrient for plant growth. The magnitude of denitrification affects the rates of decomposition of organic matter in the water column. Changes in these rates can alter the balance between the amount of carbon that reaches the deep ocean and the amount of CO2 available in the atmosphere. The project will be conducted in the Eastern Tropical North Pacific where suitably low oxygen waters persist. Various measurements of denitrification in this environment will address research questions that are crucial to understanding nitrogen and carbon cycling in the ocean. State-of-practice N-15 techniques and isotope ratio mass spectrometry will be used to determine dinitrification rates. ***
