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Ammonium concentrations at station TT007_6-TM6

Publication Date
DOI: 10.1594/pangaea.120541
  • 02172005 Tm-6
  • Ammonium
  • Ammonium Determination (Brzezinski
  • 1988)
  • Bottle
  • Multi Level Trace Metal
  • Equatorial Pacific
  • Jgofs
  • Joint Global Ocean Flux Study
  • Thomas G
  • Thompson
  • Tt007
  • Tt007_6-Tm6


BRZEZINSKI, MARK A. Vertical distribution of ammonium in stratified oligotrophic waters NOTES Limnol. Oceanogr., 33(5), 1988, 1176-I 182 0 1988, by the American Society of Limnology and Oceanography, Inc. Vertical distribution of ammonium in stratified oligotrophic waters Abstract-A method for measuring nanomolar concentrations of ammonium in seawater was used for the first time under field conditions in the Sargasso Sea and Gulf Stream. Ammonium concentrations ranged from below the limit of detection (3.5 nM) to 164 nM NH,+. Subsurface ammonium maxima (16-59 nM NH,+) occurred within the seasonal thermocline and near the deep chlorophyll a maximum in association with the primary nitrite maximum. The latter feature was observed in both the Sargasso Sea and Gulf Stream, suggesting that it may be common in stratified oligotrophic waters. VerticaIIy integrat- ed nitrite concentrations in the upper 140 m gen- erally exceeded those for ammonium, suggesting more efficient use of reduced nitrogen by the mi- croplankton. Nearly all of the organic nitrogen in the sea is converted to ammonium during re- mineralization by zooplankton and micro- heterotrophs (Dugdale and Goering 1967; Eppley and Peterson 1979; Harrison 1980). This is especially important in oligotrophic waters where ammonium can account for > 90% of the nitrogen necessary for primary production (Eppley I98 I). Ammonium also appears to be an important nitrogen source for heterotrophic bacteria in various marine systems (e.g. Laws et al. 1985; Wheeler and Kirchman 1986; Kokkinakis and Wheeler 1987) and serves as an energy source for ammonium-oxidizing bacteria. The impor- tance of ammonium to the marine nitrogen cycle has prompted many studies of its rate Acknowledgments Contribution 6829 from the Woods Hole Oceano- graphic Institution. This work was supported by a post- doctoral fellowship awarded to me by the Woods Hole Oceanographic Institution. I thank Robert Olson and Sallie

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