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Evidence of O 2 consumption in underway seawater lines: Implications for air‐sea O 2 and CO 2 fluxes
Author(s) -
Juranek Lauren W.,
Hamme Roberta C.,
Kaiser Jan,
Wanninkhof Rik,
Quay Paul D.
Publication year - 2010
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 - 10.1029/2009gl040423
Subject(s) - seawater , environmental science , environmental chemistry , oceanography , atmospheric sciences , chemistry , geology
We observed O 2 deficits of 0.5 to 2.0% (1 to 4 μ mol/kg) in the underway seawater lines of three different ships. Deficits in O 2 /Ar and isotopic enrichments in dissolved O 2 observed in underway seawater lines indicate a respiratory removal process. A 1% respiratory bias in underway lines would lead to a 2.5–5 μ atm (2.5–5 μ bar) enhancement in surface water p CO 2 . If an underway p CO 2 bias of this magnitude affected all measurements, the global oceanic carbon uptake based on p CO 2 climatologies would be 0.5–0.8 Pg/yr higher than the present estimate of 1.6 Pg/yr. Treatment of underway lines with bleach for several hours and thorough flushing appeared to minimize O 2 loss. Given the increasing interest in underway seawater measurements for the determination of surface CO 2 and O 2 fluxes, respiration in underway seawater lines must be identified and eliminated on all observing ships to ensure unbiased data.