title: Baseline monitoring of the western Arctic Ocean estimates 20% of Canadian basin surface waters are undersaturated with respect to aragonite.
abstract: Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ≈ 20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean's largest area of aragonite undersaturation to sea ice melt and atmospheric CO2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.
authors.affiliation: St. Petersburg Coastal and Marine Science Center, United States Geological Survey, St. Petersburg, Florida, United States of America.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Robbins
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Wynn
authors.forename: John T
authors.initials: JT
authors.lastname: Lisle
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Yates
authors.forename: Paul O
authors.initials: PO
authors.lastname: Knorr
authors.forename: Robert H
authors.initials: RH
authors.lastname: Byrne
authors.forename: Xuewu
authors.initials: X
authors.lastname: Liu
authors.forename: Mark C
authors.initials: MC
authors.lastname: Patsavas
authors.forename: Kumiko
authors.initials: K
authors.lastname: Azetsu-Scott
authors.forename: Taro
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D001110:Arctic Regions; D002119:Calcium Carbonate / Q000032:analysis*; D002170:Canada; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D064308:Ecological Parameter Monitoring / Q000379:methods*; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry*; D005843:Geography; D006863:Hydrogen-Ion Concentration; D046448:Ice Cover / Q000737:chemistry; D009792:Oceans and Seas; D010103:Oxygen Isotopes / Q000032:analysis; D010313:Partial Pressure; D054712:Salinity; D012623:Seawater / Q000737:chemistry*
chemical_list: D010103:Oxygen Isotopes; D002245:Carbon Dioxide; D002244:Carbon; D002119:Calcium Carbonate
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