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Vertical distribution of ammonium in stratified oligotrophic waters
Author(s) -
Brzezinski Mark A.
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.5.1176
Subject(s) - ammonium , thermocline , sargasso sea , oceanography , seawater , nitrite , environmental chemistry , environmental science , chlorophyll a , stratification (seeds) , nitrogen , chemistry , nitrate , geology , biology , botany , seed dormancy , biochemistry , germination , organic chemistry , dormancy
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 4 + . Subsurface ammonium maxima (16–59 nM NH 4 + ) 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. Vertically integrated nitrite concentrations in the upper 140 m generally exceeded those for ammonium, suggesting more efficient use of reduced nitrogen by the microplankton.