Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Jones, Elizabeth M.; Bakker, Dorothee C E; Venables, Hugh J.; Whitehouse, Martin J.; Korb, Rebecca E.; Watson, Andrew

doi:10.3402/tellusb.v62i5.16611

Cited by 10 publications

(17 citation statements)

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“…The release of excess AT to the surface waters may drive additional f CO 2 undersaturation, and elevated Ω and pH. However, our conventional salinity normalization assumes that sea ice melt water, the primary source of freshening in this system, makes a zero contribution to alkalinity, which may not be the case [e.g., Jones et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…Seasonal depletions in mixed‐layer TCO 2 were estimated from the difference between (observed) summer concentrations and an inferred winter concentration. For stations located to the north of the Adélie Sill (see Figure , in blue), the winter concentrations were estimated from the observed TCO 2 concentrations at the depth of the temperature minimum [e.g., Ishii et al ., ; Jones et al ., ]. Because the temperature minimum is not as well defined on the shelf, this method of defining the winter concentration may not be appropriate in the marginal ice zone, where some of our stations are located [e.g., Shadwick et al ., ].…”

Section: Methodsmentioning

confidence: 99%

“…The “alk” term refers to the impact of carbonate mineral formation or dissolution on TCO 2 . Because the precipitation or dissolution of CaCO 3 results in a 2:1 change in TA:TCO 2 , we estimate the “alk” term based on the AT deficit, after accounting for changes in salinity and nitrate [e.g., Jones et al ., ]. The remaining “bio + gas” term represents changes due to biological processes and gas exchange and are grouped together.…”

Section: Methodsmentioning

confidence: 99%

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Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

2017

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A marked reconfiguration of the Mertz Polynya following the 2010 calving of the Mertz Glacier Tongue has been associated with a decrease in the size and activity of the polynya. We report observations of the oceanic carbonate (CO2) system in late‐summer 2013, the third post‐calving summer season. Estimates of seasonal net community production (NCP) based on inorganic carbon deficits and the oxygen‐argon ratio indicate that the waters on the shelf to the east of Commonwealth Bay (adjacent to the Mertz Glacier) remain productive compared to pre‐calving conditions. The input of residual or excess alkalinity from melting sea ice is found to contribute to the seasonal enhancement of carbonate saturation state and pH in shelf waters. Mean rates of NCP in 2012–2013 are more than twice as large as those observed in the pre‐calving summers of 2001 and 2008 and suggest that the new (post‐calving) configuration of the polynya favors enhanced net community production and a stronger surface ocean sink for atmospheric CO2 due at least in part to the redistribution of sea ice and associated changes in summer surface stratification.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

2017

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“…− ] + [CO 3 2− ]) for the air-sea CO 2 flux have received little attention. Currently, the TCO 2 and CO 2 flux mechanisms associated with sea ice in polar seas are driven by the aforementioned sea ice-ocean TCO 2 transport (Anderson et al, 2004;Rysgaard et al, 2007;Semiletov et al, 2004) and air-sea CO 2 exchange mediated by biological, physical and chemical changes in sea-ice brines (Jones and Coote, 1981;Gleitz et al, 1995;Tison et al, 2002;Delille et al, 2007;Dieckmann et al, 2008Dieckmann et al, , 2010Jones et al, 2010) and in surface oceanic waters (Rysgaard et al, 2009;Jones et al, 2010). Here, we report a conceptual model on the season-dependent processes by which sea ice controls air-sea CO 2 exchange, and quantify the air-sea flux of CO 2 modulated by sea ice formation and decay.…”

Section: Introductionmentioning

confidence: 99%

Sea ice contribution to the air–sea CO<sub>2</sub> exchange in the Arctic and Southern Oceans

Rysgaard¹,

Bendtsen²,

Delille³

et al. 2011

Tellus B

123

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Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO 2 and the subsequent effect on air-sea CO 2 exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air-sea CO 2 exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO 2 uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO 2 uptake in ice-free polar seas. This sea-ice driven CO 2 uptake has not been considered so far in estimates of global oceanic CO 2 uptake. Net CO 2 uptake in sea-ice-covered oceans can be driven by; (1) rejection during sea-ice formation and sinking of CO 2-rich brine into intermediate and abyssal oceanic water masses, (2) blocking of air-sea CO 2 exchange during winter, and (3) release of CO 2-depleted melt water with excess total alkalinity during sea-ice decay and (4) biological CO 2 drawdown during primary production in sea ice and surface oceanic waters.

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“…Those authors point to the persistent O 2 deficit as an indicator that gas exchange is reduced in winter. In contrast to these observations Bakker et al [1997] observed CO 2 supersaturation in the Weddell Gyre as ice cover retreated, implying a flux of CO 2 to the atmosphere, and Jones et al [2010] report that both phytoplankton and alkalinity, deposited in the surface ocean during sea ice melt may result in high CO 2 uptake during summer. However, as Yager et al [1995] noted, the seasonal rectification of CO 2 in the surface ocean depends upon the rate of air‐sea gas exchange and upon the upwelling and diapycnal exchange into the mixed layer, which cannot be inferred from oxygen and inorganic carbon alone.…”

Section: Introductionmentioning

confidence: 70%

Sea ice and its effect on CO₂ flux between the atmosphere and the Southern Ocean interior

Loose

Schlosser

2011

J. Geophys. Res.

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[1] The advance and retreat of sea ice produces seasonal convection and stratification, dampens surface waves and creates a separation between the ocean and atmosphere. These are all phenomena that can affect the air-sea gas transfer velocity (k 660 ), and therefore it is not straightforward to determine how sea ice cover modulates air-sea flux. In this study we use field estimates k 660 to examine how sea ice affects the net gas flux between the ocean and atmosphere. An inventory of salinity, 3 He, and CFC-11 in the mixed layer is used to infer k 660 during the drift of Ice Station Weddell in 1992. The average of k 660 is 0.11 m d −1 across nearly 100% ice cover. In comparison, the only prior field estimates of k 660 are disproportionately larger, with average values of 2.4 m d −1 across 90% sea ice cover, and 3.2 m d −1 across approximately 70% sea ice cover. We use these values to formulate two scenarios for the modulation of k 660 by the fraction of sea ice cover in a 1-D transport model for the Southern Ocean seasonal ice zone. Results show the net CO 2 flux through sea ice cover represents 14-46% of the net annual air-sea flux, depending on the relationship between sea ice cover and k 660 . The model also indicates that as much as 68% of net annual CO 2 flux in the sea ice zone occurs in the springtime marginal ice zone, which demonstrates the need for accurate parameterizations of gas flux and primary productivity under partially ice-covered conditions. Citation: Loose, B., and P. Schlosser (2011), Sea ice and its effect on CO 2 flux between the atmosphere and the Southern Ocean interior,

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Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Cited by 10 publications

References 0 publications

Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

Sea ice contribution to the air–sea CO<sub>2</sub> exchange in the Arctic and Southern Oceans

Sea ice and its effect on CO₂ flux between the atmosphere and the Southern Ocean interior

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Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Cited by 10 publications

References 0 publications

Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

Late‐summer biogeochemistry in the Mertz Polynya: East Antarctica

Sea ice contribution to the air–sea CO<sub>2</sub> exchange in the Arctic and Southern Oceans

Sea ice and its effect on CO2 flux between the atmosphere and the Southern Ocean interior

Contact Info

Product

Resources

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Sea ice and its effect on CO₂ flux between the atmosphere and the Southern Ocean interior