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Effect of glacial drainage water on the CO 2 system and ocean acidification state in an A rctic tidewater‐glacier fjord during two contrasting years
Author(s) -
Fransson Agneta,
Chierici Melissa,
Nomura Daiki,
Granskog Mats A.,
Kristiansen Svein,
Martma Tõnu,
Nehrke Gernot
Publication year - 2015
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010320
Subject(s) - fjord , alkalinity , glacial period , ocean acidification , carbonate , total inorganic carbon , seawater , salinity , oceanography , glacier , dissolved organic carbon , calcite , environmental science , dolomite , geology , carbon dioxide , hydrology (agriculture) , chemistry , mineralogy , geomorphology , geotechnical engineering , organic chemistry
In order to investigate the effect of glacial water on the CO 2 system in the fjord, we studied the variability of the total alkalinity (A T ), total dissolved inorganic carbon (C T ), dissolved inorganic nutrients, oxygen isotopic ratio (δ 18 O), and freshwater fractions from the glacier front to the outer Tempelfjorden on Spitsbergen in winter 2012 (January, March, and April) and 2013 (April) and summer/fall 2013 (September). The two contrasting years clearly showed that the influence of freshwater, mixing, and haline convection affected the chemical and physical characteristics of the fjord. The seasonal variability showed the lowest calcium carbonate saturation state (Ω) and pH values in March 2012 coinciding with the highest freshwater fractions. The highest Ω and pH were found in September 2013, mostly due to CO 2 uptake during primary production. Overall, we found that increased freshwater supply decreased Ω, pH, and A T . On the other hand, we observed higher A T relative to salinity in the freshwater end‐member in the mild and rainy winter of 2012 (1142 μmol kg −1 ) compared to A T in 2013 (526 μmol kg −1 ). Observations of calcite and dolomite crystals in the glacial ice suggested supply of carbonate‐rich glacial drainage water to the fjord. This implies that winters with a large amount of glacial drainage water partly provide a lessening of further ocean acidification, which will also affect the air‐sea CO 2 exchange.