Inorganic carbon transport during sea ice growth and decay: A carbon pump in polar seas

Rysgaard, Søren; Glud, Ronnie N.; Sejr, Mikael K.; Bendtsen, Jørgen; Christensen, P. B.

doi:10.1029/2006jc003572

Cited by 218 publications

(382 citation statements)

References 32 publications

(43 reference statements)

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“…Results in situ, however, demonstrate that this limitation may act only within a low range of CO 2 concentrations, up to a threshold of about 150 µatm, below which nutrient depletion would outweigh CO 2 limitation. Surface water in the European Arctic in the spring is depleted in CO 2 owing to strong net community production during the bloom 2,13 and freshening by sea-ice melting 10 , resulting in the lowest p CO 2 values reported anywhere in the ocean 11 , with values as low as 135 µatm found in our field survey, and 45 µatm reported in the literature 21 .…”

mentioning

confidence: 52%

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

et al. 2015

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The Arctic Ocean is warming at two to three times the global rate 1 and is perceived to be a bellwether for ocean acidification 2,3 . Increased CO 2 concentrations are expected to have a fertilization e ect on marine autotrophs 4 , and higher temperatures should lead to increased rates of planktonic primary production 5 . Yet, simultaneous assessment of warming and increased CO 2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO 2 -enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO 2 enhances GPP (by a factor of up to ten) over a range of 145-2,099 µatm; however, the greatest e ects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO 2 -enhanced primary production has significant implications for metabolic balance in a warmer, CO 2 -enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.Primary production in the Arctic Ocean supports significant fisheries 6 and renders it an important sink for anthropogenic carbon 2 ; however, climate change has the potential to alter these capacities. Accelerated ice loss is opening surface area across the Arctic, resulting in observations of increased rates of primary production 7 . The reduced salinity caused by melting ice, combined with increasing temperatures, however, increases stratification, restricting turbulent nutrient supply to surface layers 8 . Ice loss also increases surface area for air-sea CO 2 exchange, causing an uptake from the atmosphere into surface waters with already low p CO 2 (ref. 9), and ice melt introduces freshwater with low alkalinity and dissolved inorganic carbon, further lowering the carbon content of surface waters 10 . The surface waters of the Arctic Ocean are largely undersaturated with respect to CO 2 throughout spring and summer 2 . In the European sector of the Arctic Ocean (BarentsGreenland Sea/Fram Strait), p CO 2 varies seasonally by more than 200 µatm, with values as low as 100 µatm in spring months 11 owing to strong net community production associated with the spring bloom of ice algae followed by that of planktonic algae

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confidence: 52%

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

et al. 2015

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“…Overall, a weak trend toward higher d 13 C DIC with increasing meltwater contribution is seen in some datasets. This pattern may be related to the notion that sea-ice meltwater adds nutrients to the water column and, thereby, enables biological production and also adds to the DIC pool [40]. However, there is no indication of an effect of sea-ice formation and thus sea-ice related brines on d 13 C as .…”

Section: Influence Of River D 13 C Dic and Brine Enriched Watersmentioning

confidence: 93%

A baseline for the vertical distribution of the stable carbon isotopes of dissolved inorganic carbon (δ13CDIC) in the Arctic Ocean

Bauch

Polyak

Ortiz

2015

Arktos

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Stable carbon isotopes of dissolved inorganic carbon (d 13 C DIC ) in the ocean are generally not well understood as they are governed by a complex interplay of biological processes and air-sea exchange. In the Arctic Ocean, d 13 C DIC values are prone to change in the near future with rapidly changing climate conditions. This study provides a baseline to assess the d 13 C DIC of the Arctic Ocean with a focus on upper to intermediate waters (to *500 m). Measured d 13 C DIC values in the Arctic Ocean range from *-0.6 to ?2.2 %. In the Eurasian Basin, the d 13 C DIC values lie between *1 and 1.5 % and exhibit little variation within the upper layers. In the Canada Basin, d 13 C DIC values reach 2 % in the surface layer, with lowest values of *-0.6 % found at *200 m water depth. At greater depth, d 13 C DIC values range from *1 to 1.5 % within both basins. In the Canada Basin, nutrient levels are higher than in the Eurasian Basin and associated variations in d 13 C DIC are clearly related to biological processes. However, low d 13 C DIC values in the Canada Basin are also strongly influenced by non-equilibrium air-sea exchange processes. The different d 13 C DIC patterns between the Canada Basin and the Eurasian Basin appear to be linked to differences in transport processes within the Arctic Ocean halocline. The upper layers in the Canada basins have direct contributions of waters from the Laptev, East Siberian and Chukchi shelves, which contain elevated fractions of river waters and sea-ice related brines, whereas their counterparts, in the Eurasian Basin, are mostly formed by halocline waters from the Barents and Kara seas. River waters have low d 13 C DIC of *-8 % on average, but in the Arctic basins this signal is mostly lost and d 13 C DIC values show only a weak correlation to river water fractions contained in the water mass. No relation between d 13 C DIC and sea-ice related brine contribution is apparent.

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“…2004; Nomura et al, 2006;Papadimitriou et al, 2004;Rysgaard et al, 2007Rysgaard et al, , 2011Rysgaard et al, , 2012Rysgaard et al, , 2013.…”

Section: Introductionunclassified

“…The coupling of the air-ice-ocean carbonate system has been suggested to drive a significant annual net uptake of CO 2 , through convective sequestration of CO 2 to intermediate and deeper ocean layers during wintertime sea-ice formation and subsequent CO 2 uptake from the atmosphere during springtime sea-ice melt (Rysgaard et al, 2009;Rysgaard et al, 2007). Together with seasonal biological carbon uptake within the ice (Thomas and Dieckmann, 2010;Lizotte, 2001), this outlines the basis for a seasonal carbon imbalance, which may drive CO 2 uptake from the atmosphere during springtime melting of sea ice, and mineral dissolution of trapped calcium carbonate (CaCO 3 ) within the brine channels.…”

Section: Introductionmentioning

confidence: 99%

“…Together with seasonal biological carbon uptake within the ice (Thomas and Dieckmann, 2010;Lizotte, 2001), this outlines the basis for a seasonal carbon imbalance, which may drive CO 2 uptake from the atmosphere during springtime melting of sea ice, and mineral dissolution of trapped calcium carbonate (CaCO 3 ) within the brine channels. The net uptake associated with this sea-ice-driven carbon pump has been estimated to be 50 MT C yr −1 in the Arctic alone (Rysgaard et al, 2007) and constitutes an important fraction of the total CO 2 uptake of the Arctic Ocean (66-199 MT C yr −1 ) (Parmentier et al, 2013). The size of these estimates highlights the importance of the annual sea-ice cycle on the global carbon cycle, particularly since the sea-ice cover is becoming more ephemeral over a range of space and timescales .…”

Section: Introductionmentioning

confidence: 99%

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Winter observations of CO<sub>2</sub> exchange between sea ice and the atmosphere in a coastal fjord environment

et al. 2015

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Abstract. Eddy covariance observations of CO 2 fluxes were conducted during March-April 2012 in a temporally sequential order for 8, 4 and 30 days, respectively, at three locations on fast sea ice and on newly formed polynya ice in a coastal fjord environment in northeast Greenland. CO 2 fluxes at the sites characterized by fast sea ice (ICEI and DNB) were found to increasingly reflect periods of strong outgassing in accordance with the progression of springtime warming and the occurrence of strong wind events: F ICE1 CO 2 = 1.73 ± 5 mmol m −2 day −1 and F DNB CO 2 = 8.64 ± 39.64 mmol m −2 day −1 , while CO 2 fluxes at the polynya site (POLYI) were found to generally reflect uptake F POLY1 CO 2 = −9.97 ± 19.8 mmol m −2 day −1 . Values given are the mean and standard deviation, and negative/positive values indicate uptake/outgassing, respectively. A diurnal correlation analysis supports a significant connection between site energetics and CO 2 fluxes linked to a number of possible thermally driven processes, which are thought to change the pCO 2 gradient at the snow-ice interface. The relative influence of these processes on atmospheric exchanges likely depends on the thickness of the ice. Specifically, the study indicates a predominant influence of brine volume expansion/contraction, brine dissolution/concentration and calcium carbonate formation/dissolution at sites characterized by a thick sea-ice cover, such that surface warming leads to an uptake of CO 2 and vice versa, while convective overturning within the sea-ice brines dominate at sites characterized by comparatively thin sea-ice cover, such that nighttime surface cooling leads to an uptake of CO 2 to the extent permitted by simultaneous formation of superimposed ice in the lower snow column.

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Inorganic carbon transport during sea ice growth and decay: A carbon pump in polar seas

Cited by 218 publications

References 32 publications

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

A baseline for the vertical distribution of the stable carbon isotopes of dissolved inorganic carbon (δ13CDIC) in the Arctic Ocean

Winter observations of CO<sub>2</sub> exchange between sea ice and the atmosphere in a coastal fjord environment

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Inorganic carbon transport during sea ice growth and decay: A carbon pump in polar seas

Cited by 218 publications

References 32 publications

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

A baseline for the vertical distribution of the stable carbon isotopes of dissolved inorganic carbon (δ13CDIC) in the Arctic Ocean

Winter observations of CO&lt;sub&gt;2&lt;/sub&gt; exchange between sea ice and the atmosphere in a coastal fjord environment

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Winter observations of CO<sub>2</sub> exchange between sea ice and the atmosphere in a coastal fjord environment