Late winter biogeochemical conditions under sea ice in the Canadian High Arctic

Findlay, Helen S.; Edwards, Laura A.; Lewis, Ceri; Cooper, Glenn A.; Clement, Robert; Hardman-Mountford, Nick J.; Vagle, Svein; Miller, Lisa A.

doi:10.3402/polar.v34.24170

Cited by 4 publications

(7 citation statements)

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“…The fundamental parameter driving this pump is the TA : TIC ratio in sea ice, which if only affected by ikaite should range from 2 : 1 (the theoretical maximum ratio) to approximately 1 : 1 (seawater typically has a ratio near 1 : 1, which should be reflected in sea ice if brine is rejected conservatively). Published results have reported ratios spanning 0.9 to 2.2 from a variety of different Arctic and Antarctic field sites (Rysgaard et al, 2007(Rysgaard et al, , 2009Miller et al, 2011a, b;Geilfus et al, 2012;Brown et al, 2015;Findlay et al, 2015). The absolute concentration values of TIC and TA in sea ice also span a significant range: for the above-listed studies, these values range from < 100 to > 700 µmol kg −1 for both species.…”

Section: Introductionmentioning

confidence: 95%

Variability in sea ice carbonate chemistry: a case study comparing the importance of ikaite precipitation, bottom-ice algae, and currents across an invisible polynya

et al. 2022

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Abstract. The carbonate chemistry of sea ice is known to play a role in global carbon cycles, but its importance is uncertain in part due to disparities in reported results. Variability in physical and biological drivers is usually invoked to explain differences between studies. In the Canadian Arctic Archipelago, “invisible polynyas” – areas of strong currents, thin ice, and potentially high biological productivity – are examples of extreme spatial variability. We used an invisible polynya as a natural laboratory to study the effects of inferred initial ice formation conditions, ice growth rate, and algal biomass on the distribution of carbonate species by collecting enough cores to perform a statistical comparison between sites located within, and just outside of, a polynya near Iqaluktuttiaq (Cambridge Bay, Nunavut, Canada). At both sites, the uppermost 10 cm ice horizon showed evidence of CO2 off-gassing, while carbonate distributions in the middle and bottommost 10 cm horizons largely followed the salinity distribution. In the polynya, the upper ice horizon had significantly higher bulk total inorganic carbon (TIC), total alkalinity (TA), and salinity potentially due to freeze-up conditions that favoured frazil ice production. The middle ice horizons were statistically indistinguishable between sites, suggesting that ice growth rate is not an important factor for the carbonate distribution under mid-winter conditions. The thicker (non-polynya) site experienced higher algal biomass, TIC, and TA in the bottom horizon. Carbonate chemistry in the bottom horizon could largely be explained by the salinity distribution, with the strong currents at the polynya site potentially playing a role in desalinization; biology appeared to exert only a minor control, with some evidence that the ice algae community was net heterotrophic. We did see evidence of calcium carbonate precipitation but with little impact on the TIC:TA ratio and little difference between sites. Because differences were constrained to relatively thin layers at the top and bottom, vertically averaged values of TIC, TA, and especially the TIC:TA ratio were not meaningfully different between sites. This provides some justification for using a single bulk value for each parameter when modelling sea ice effects on ocean chemistry at coarse resolution. Exactly what value to use (particularly for the TIC:TA ratio) likely varies by region but could potentially be approximated from knowledge of the source seawater and sea ice salinity. Further insights await a rigorous intercomparison of existing data.

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Section: Introductionmentioning

confidence: 95%

Variability in sea ice carbonate chemistry: a case study comparing the importance of ikaite precipitation, bottom-ice algae, and currents across an invisible polynya

et al. 2022

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“…Setting aside the TA:TIC ratio, the actual values of bulk ice TIC and TA (Table 4) that we observed are fairly consistent with other measurements from the Canadian Arctic Archipelago. Rysgaard et al (2009), Miller et al (2011a), Findlay et al (2015 and Brown et al (2015) all report values between ~300-400 µmol kg -1 for TA, and 350-450 µmol kg -1 for TIC. Higher values (up to ~700 µmol kg -1 for both TIC and TA) have been reported in deep Arctic basins and around Greenland (Rysgaard et al, 2009).…”

Section: Implications For Understanding Ikaite In Sea Icementioning

confidence: 98%

“…But average TA:TIC ratios in our samples were close to 1.05 in the bottom and middle ice horizons (Table 1), and not meaningfully different from our estimate of the source seawater TA:TIC ratio (1.04). While the original formulation of the sea ice pump hypothesis (Rysgaard et al, 2007) reported bulk TA:TIC ratios approaching 2:1, the majority of studies since have reported values close to 1:1 below the surface ice layers (Miller et al, 2011a(Miller et al, , 2011bGeilfus et al, 2012;Brown et al, 2015;Findlay et al, 2015).…”

Section: Implications For Understanding Ikaite In Sea Icementioning

confidence: 99%

“…ikaite should range from 2:1 (the theoretical maximum ratio) to approximately 1:1 (seawater typically has a ratio near 1:1, which should be reflected in sea ice if brine is rejected conservatively). Published results have reported ratios spanning 0.9 to 2.2 from a variety of different Arctic and Antarctic field sites (Rysgaard et al, 2007(Rysgaard et al, , 2009Miller et al, 2011aMiller et al, , 2011bGeilfus et al, 2012;Brown et al, 2015;Findlay et al, 2015). The absolute concentration values of TIC and TA in sea ice also span a significant range:…”

Section: Introductionmentioning

confidence: 98%

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Variability in sea ice carbonate chemistry: A case study comparing the importance of ikaite precipitation, bottom ice algae, and currents across an invisible polynya

Else

Cranch

Sims

et al. 2021

Preprint

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Abstract. The carbonate chemistry of sea ice is known to play a role in global carbon cycles, but its importance is uncertain in part due to disparities in reported results. Variability in physical and biological drivers is usually invoked to explain differences between studies. In the Canadian Arctic Archipelago, “invisible polynyas” – areas of strong currents, thin ice, and potentially high biological productivity – are examples of extreme spatial variability. We used an invisible polynya as a natural laboratory to study the effects of inferred initial ice formation conditions, ice growth rate, and algal biomass on the distribution of carbonate species by collecting enough cores to perform a statistical comparison between sites located within, and just outside of, a polynya near Iqaluktuttiaq (Cambridge Bay, Nunavut, Canada). At both sites, the uppermost 10-cm ice horizon showed evidence of CO2 offgassing, while carbonate distributions in the middle and bottommost 10-cm horizons largely followed the salinity distribution. In the polynya, the upper-ice horizon had significantly higher bulk total inorganic carbon (TIC), total alkalinity (TA), and salinity, potentially due to freeze-up conditions that favoured frazil ice production. The middle-ice horizons were statistically indistinguishable between sites, suggesting that ice growth rate is not an important factor for the carbonate distribution under mid-winter conditions. The thicker (non-polynya) site experienced higher algal biomass, TIC, and TA in the bottom horizon. Carbonate chemistry in the bottom horizon could be explained by the salinity distribution, with the strong currents at the polynya site potentially playing a role in desalinisation; biology did not have a noticeable impact. We did see evidence of calcium carbonate precipitation, but with little impact on the TIC : TA ratio, and little difference between sites. Because differences were constrained to relatively thin layers at the top and bottom, vertically averaged values of TIC, TA, and especially the TIC : TA ratio were not meaningfully different between sites. This provides some justification for using a single bulk value for each parameter when modeling sea ice effects on ocean chemistry at coarse resolution. Exactly what value to use (particularly for the TIC : TA ratio) likely varies by region but could potentially be approximated from knowledge of the source seawater and sea ice salinity. Further insights await a rigorous intercomparison of existing data.

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“…Two of these (Findlay, Gibson et al 2015;Kę dra et al 2015) also present scenarios of future change, and the conclusions of the third paper (Wegner et al 2015) serve a similar purpose. Four papers cover case studies of the plankton responses to temperature increase and changing conditions in the Arctic Ocean over short and long timeframes (Nö thig et al 2015) and in experimental studies , patterns and trends of benthic macrofauna in the deep Arctic Ocean and winter biogeochemical conditions under sea ice in the Canadian High Arctic (Findlay, Edwards et al 2015). It is anticipated that further papers stemming Foreword to the ART thematic cluster M. Kę dra et al from the Sopot workshop and other ART meetings, for example, the Integrating Spatial and Temporal Scales in the Changing Arctic System workshop in Plouzané in 2014, will be published elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Foreword to the thematic cluster: the Arctic in Rapid Transition—marine ecosystems

et al. 2015

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Late winter biogeochemical conditions under sea ice in the Canadian High Arctic

Cited by 4 publications

References 60 publications

Variability in sea ice carbonate chemistry: a case study comparing the importance of ikaite precipitation, bottom-ice algae, and currents across an invisible polynya

Variability in sea ice carbonate chemistry: a case study comparing the importance of ikaite precipitation, bottom-ice algae, and currents across an invisible polynya

Variability in sea ice carbonate chemistry: A case study comparing the importance of ikaite precipitation, bottom ice algae, and currents across an invisible polynya

Foreword to the thematic cluster: the Arctic in Rapid Transition—marine ecosystems

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