Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine

Gleitz, Markus; Loeff, Michiel Rutgers v. d.; Thomas, David N.; Dieckmann, Gerhard; Millero, Frank J.

doi:10.1016/0304-4203(95)00053-t

Cited by 198 publications

(208 citation statements)

References 32 publications

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“…For SIM (figure 4c), highest percentages are visible in the surface layers associated with the recent seasonal decrease in sea-ice extent (approx. stations [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. This reaches a maximum of 1.8% at station 84, equivalent to 0.8 m of sea-ice derived freshwater in an 85 m thick Surface Water (neutral density γ n < 27.55) layer.…”

Section: Resultsmentioning

confidence: 99%

“…For MET, the salinity endmember was set to 0, whilst for sea-ice a salinity of 5 [68] and a δ 18 O of +1.8 (taken as representative of surface waters in this region adjusted for the fractionation that occurs during freezing [69]) were used. Estimates of 'PO' were formulated from mean phosphate and oxygen measurements taken from Antarctic snow (for the meteoric endmember [70][71][72][73][74] and sea-ice [74][75][76][77][78]). The δ 18 O endmember for MET carries the greatest uncertainty, as it must represent a combination of both local (seasonally varying) precipitation and glacial melt, which can encompass a large variability in δ 18 O signal depending on the exact latitude and elevation at which the precipitation accumulated.…”

Section: (D) Determination Of Freshwater Sourcesmentioning

confidence: 99%

See 1 more Smart Citation

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Brown

Meredith

Jullion

et al. 2014

Phil. Trans. R. Soc. A.

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Full-depth measurements of δ 18 O from 2008 to 2010 enclosing the Weddell Gyre in the Southern Ocean are used to investigate the regional freshwater budget. Using complementary salinity, nutrients and oxygen data, a four-component mass balance was applied to quantify the relative contributions of meteoric water (precipitation/glacial input), sea-ice melt and saline (oceanic) sources. Combination of freshwater fractions with velocity fields derived from a box inverse analysis enabled the estimation of gyre-scale budgets of both freshwater types, with deep water exports found to dominate the budget. Surface net sea-ice melt and meteoric contributions reach 1.8% and 3.2%, respectively, influenced by the summer sampling period, and −1.7% and +1.7% at depth, indicative of a dominance of sea-ice production over melt and a sizable contribution of shelf waters to deep water mass formation. A net meteoric water export of approximately 37 mSv is determined, commensurate with local estimates of ice sheet outflow and precipitation, and the Weddell Gyre is estimated to be a region of net sea-ice production. These results constitute the first synoptic benchmarking of sea-ice and meteoric exports from the Weddell Gyre, against which future change associated with an accelerating hydrological cycle, ocean climate change and evolving Antarctic glacial mass balance can be determined.

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Section: Resultsmentioning

confidence: 99%

Section: (D) Determination Of Freshwater Sourcesmentioning

confidence: 99%

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Brown

Meredith

Jullion

et al. 2014

Phil. Trans. R. Soc. A.

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“…Brine samples from sea ice were obtained using the sack hole method (e.g., Gleitz et al, 1995). A 0.5 m depth hole was drilled below the ice surface using an ice corer, and then covered with a 5 cm-thick urethane lid to reduce heat and gas transfer across the brine/atmosphere interface.…”

Section: Measurements and Sampling Methodsmentioning

confidence: 99%

Rapid physically driven inversion of the air–sea ice CO2 flux in the seasonal landfast ice off Barrow, Alaska after onset of surface melt

Nomura

Eicken

Gradinger

et al. 2010

Continental Shelf Research

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The air-sea ice CO 2 flux was measured over landfast sea ice in the Chukchi Sea, off Barrow, Alaska in late May 2008 with a chamber technique. The ice cover transitioned from a cold early spring to a warm late spring state, with an increase in air temperature and incipient surface melt. During melt, brine salinity and brine dissolved inorganic carbon concentration (DIC) decreased from 67.3 to 18.7 and 3977.6 to 1163.5 μmol kg −1 , respectively. In contrast, the salinity and DIC of under-ice water at depths of 3 and 5 m below the ice surface remained almost constant with average values of 32.4±0.3 (standard deviation) and 2163.1±16.8 μmol kg −1 , respectively. The air-sea ice CO 2 flux decreased from +0.7 to −1.0 mmol m −2 day −1 (where a positive value indicates CO 2 being released to the atmosphere from the ice surface). During this early to late spring transition, brought on by surface melt, sea ice shifted from a source to a sink for atmospheric CO 2 , with a rapid decrease of brine DIC likely associated with a decrease in the partial pressure of CO 2 of brine from a supersaturated to an undersaturated state compared to the atmosphere. Formation of superimposed ice coincident with melt was not sufficient to shut down ice-air gas exchange.

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“…Brines were sampled using the sack-hole sampling technique at 20 and 40 cm below the ice surface (Gleitz et al, 1995). Each sack hole was covered with a plastic lid to prevent snow and ice shavings from falling into the pit (Thomas et al, 2010).…”

Section: Field Samplingmentioning

confidence: 99%

CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input

et al. 2014

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Abstract. We present the CH 4 concentration [CH 4 ], the partial pressure of CO 2 (pCO 2 ) and the total gas content in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. Fjord systems are characterized by freshwater runoff and riverine input and based on δ 18 O data, we show that > 30 % of the surface water originated from periodic river input during ice growth. This resulted in fresher sea-ice layers with higher gas content than is typical from marine sea ice. The bulk ice [CH 4 ] ranged from 1.8 to 12.1 nmol L −1 , which corresponds to a partial pressure ranging from 3 to 28 ppmv. This is markedly higher than the average atmospheric methane content of 1.9 ppmv. Evidently most of the trapped methane within the ice was contained inside bubbles, and only a minor portion was dissolved in the brines. The bulk ice pCO 2 ranged from 60 to 330 ppmv indicating that sea ice at temperatures above −4 • C is undersaturated compared to the atmosphere (390 ppmv). This study adds to the few existing studies of CH 4 and CO 2 in sea ice, and we conclude that subarctic seawater can be a sink for atmospheric CO 2 , while being a net source of CH 4 .

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Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine

Cited by 198 publications

References 32 publications

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Rapid physically driven inversion of the air–sea ice CO2 flux in the seasonal landfast ice off Barrow, Alaska after onset of surface melt

CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input

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Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine

Cited by 198 publications

References 32 publications

Freshwater fluxes in the Weddell Gyre: results from δ 18 O

Freshwater fluxes in the Weddell Gyre: results from δ 18 O

Rapid physically driven inversion of the air–sea ice CO2 flux in the seasonal landfast ice off Barrow, Alaska after onset of surface melt

CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in sea ice from a subarctic fjord under influence of riverine input

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Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input