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Decadal changes in the CaCO 3 saturation state along 179°E in the Pacific Ocean
Author(s) -
Murata Akihiko,
Saito Shu
Publication year - 2012
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 - 10.1029/2012gl052297
Subject(s) - isopycnal , aragonite , seawater , saturation (graph theory) , oceanography , pacific ocean , latitude , geology , ocean acidification , mineralogy , environmental science , calcite , mathematics , geodesy , combinatorics
To assess degrees of ocean acidification, we mainly investigated decadal changes in the saturation state of seawater with respect to aragonite (Ω arg ), which is a more vulnerable mineral form of CaCO 3 , along the 179°E meridian (WOCE P14N) in the Pacific Ocean. We found a maximum decrease of Ω arg of −0.48 (−0.034 a −1 ) at 200–300 dbar (isopycnal surfaces of 24.0–25.8 kg m −3 ) at 20°N. Between 1993 and 2007, the saturation horizon rose by 17 dbar (1.2 dbar a −1 ) at latitudes 10°N–50°N. Although ΔΩ arg mostly reflected changes in normalized dissolved inorganic carbon (ΔnC T ), it was larger than could be explained by anthropogenic CO 2 storage alone. Decomposition of ΔnC T revealed that ΔΩ arg was enhanced by approximately 50% by a non‐anthropogenic CO 2 contribution represented by changes in apparent oxygen utilization. Our results suggest that ocean acidification can be temporarily accelerated by temporal changes in oceanic conditions.