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Field observations of the ocean‐atmosphere exchange of ammonia: Fundamental importance of temperature as revealed by a comparison of high and low latitudes
Author(s) -
Johnson Martin T.,
Liss Peter S.,
Bell Thomas G.,
Lesworth Timothy J.,
Baker Alex R.,
Hind Andrew J.,
Jickells Timothy D.,
Biswas Karabi F.,
Woodward E. Malcolm S.,
Gibb Stuart W.
Publication year - 2008
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2007gb003039
Subject(s) - atmosphere (unit) , seawater , latitude , ocean gyre , environmental science , oceanography , atmospheric sciences , sea surface temperature , ammonium , ammonia , climatology , geology , chemistry , subtropics , meteorology , geography , geodesy , organic chemistry , fishery , biology
Simultaneous measurements of NH 3 in the atmosphere and NH 4 + in the ocean are presented from fieldwork spanning 10 years and 110 degrees of latitude, including the first such simultaneous measurements in the remote marine environment at >55°N. At high latitudes, fluxes were almost exclusively from air to sea, in contradiction with previous lower‐latitude studies, which have suggested that the open oceans are predominantly sources of ammonia to the atmosphere. Sensitivity analysis demonstrates that the direction and magnitude of the ocean‐atmosphere NH 3 exchange is highly dependent on water temperature. This temperature effect is sufficiently strong to outweigh the effects of variability in concentrations in seawater and atmosphere in many parts of the (open) ocean. This is highlighted in data from the Atlantic oligotrophic gyres, where fluxes were found to be predominantly out of the ocean despite extremely low dissolved ammonium concentrations in surface waters.