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Title: Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

The carbonate chemistry in the Dalton Polynya in East Antarctica (115°–123°E) was investigated in summer 2014/2015 using high‐frequency underway measurements of CO2fugacity (fCO2) and discrete water column measurements of total dissolved inorganic carbon (TCO2) and total alkalinity. Air‐sea CO2fluxes indicate this region was a weak net source of CO2to the atmosphere (0.7 ± 0.9 mmol C m−2day−1) during the period of observation, with the largest degree of surface water supersaturation (ΔfCO2= +45 μatm) in ice‐covered waters near the Totten Ice Shelf (TIS) as compared to the ice‐free surface waters in the Dalton Polynya. The seasonal depletion of mixed‐layer TCO2(6 to 51 μmol/kg) in ice‐free regions was primarily driven by sea ice melt and biological CO2uptake. Estimates of net community production (NCP) reveal net autotrophy in the ice‐free Dalton Polynya (NCP = 5–20 mmol C m−2day−1) and weakly heterotrophic waters near the ice‐covered TIS (NCP = −4–0 mmol C m−2day−1). Satellite‐derived estimates of chlorophylla(Chla) and sea ice coverage suggest that the early summer season in 2014/2015 was anomalous relative to the long‐term (1997–2017) record, with lower surface Chlaconcentrations and a greater degree of sea ice cover during the period of observation; the implications for seasonal primary production and air‐sea CO2exchange are discussed. This study highlights the importance of both physical and biological processes in controlling air‐sea CO2fluxes and the significant interannual variability of the CO2system in Antarctic coastal regions.

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Author(s) / Creator(s):
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Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Journal of Geophysical Research: Oceans
Page Range / eLocation ID:
p. 5634-5653
Medium: X
Sponsoring Org:
National Science Foundation
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