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Gas exchange, dispersion, and biological productivity on the West Florida Shelf: Results from a Lagrangian Tracer Study
Author(s) -
Wanninkhof Rik,
Hitchcock Gary,
Wiseman William J.,
Vargo Gabe,
Ortner Peter B.,
Asher William,
Ho David T.,
Schlosser Peter,
Dickson MaryLynn,
Masserini Robert,
Fanning Kent,
Zhang JiaZhong
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl01757
Subject(s) - tracer , trace gas , environmental science , productivity , dispersion (optics) , remineralisation , carbon fibers , dissolved organic carbon , carbon dioxide , atmospheric sciences , hydrology (agriculture) , atmosphere (unit) , water column , environmental chemistry , chemistry , oceanography , meteorology , geology , materials science , physics , inorganic chemistry , geotechnical engineering , fluoride , organic chemistry , composite number , nuclear physics , optics , economics , composite material , macroeconomics
A Lagrangian tracer study was performed on the west Florida shelf in April 1996 using deliberately injected trace gases. Although such studies have been performed previously, this work is the first where the deliberate tracers, in conjunction with carbon system parameters, are used to quantify changes in water column carbon inventories due to air‐sea exchange and net community metabolism. The horizontal dispersion and the gas transfer velocity were determined over a period of 2 weeks from the change in both the concentrations and the concentration ratio of the two injected trace gases, sulfur hexafluoride (SF 6 ) and helium‐3 (³He). The second moment of the patch grew to 1.6 × 10³ km² over a period of 11 days. The gas transfer velocity, normalized to CO 2 exchange at 20°C, was 8.4 cm hr −1 at an average wind speed, U 10 , of 4.4 m s −1 for the duration of the experiment, which is in good agreement with empirical estimates. Remineralization rates exceeded productivity, causing an increase in dissolved inorganic carbon of about 1 µmol kg −1 day −1 in the water column. During this period of senescence, 80% of the increase in inorganic carbon is attributed to community remineralization and 20% due to invasion of atmospheric CO 2 .