An ammonium enrichment event in the surface ocean: Wind forcing and potential ramifications

article Ammonium is a nutrient frequently preferred by microorganisms that photosynthesize at the base of the marine food web and remove atmospheric carbon dioxide via carbon fixation. Because their photosynthesis is concentrated in the ocean's thin euphotic zone, its nutrient concentrations are critical to oceanic carbon fixation. Identification of replacement processes for euphotic-zone ammonium thus becomes important. These processes were investigated in a two-experiment, Lagrangian field study that produced results consistent with an apparent inverse effect of wind forcing on upper-ocean ammonium concentrations. At low wind speeds (especially ≤4ms −1 ), continuoussea-