Frost flowers growing in the Arctic ocean‐atmosphere–sea ice–snow interface: 1. Chemical composition

Douglas, Thomas A.; Dominé, Florent; Barret, Manuel; Anastasio, Cort; Beine, H. J.; Bottenheim, J. W.; Grannas, A. M.; Houdier, Stéphan; Netcheva, S.; Rowland, G. A.; Staebler, R. M.; Steffen, Alexandra

doi:10.1029/2011jd016460

Cited by 72 publications

(105 citation statements)

References 98 publications

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“…During that season, an exponential increase in reactive halogens ("bromine explosions") -of which bromine monoxide (BrO) is an indicator -induces (i) a boundary-layer ozone depletion and (ii) mercury deposition in the polar regions [see, e.g., Simpson et al, 2007;and references therein]. Frost flowers [Rankin et al, 2002] were the first candidate for the strong BrO source, because of their high content in brine, a potentially large specific surface area, and the associated enrichment in major ions compared to seawater [Douglas et al, 2012]. Backtracking atmospheric parcel trajectories identified young ice regions as sources of bromine explosions and ozone depletion in the Antarctic sea ice zone [Kaleschke et al, 2004;Jones et al, 2006].…”

Section: Sea Ice Surface Bromine and Tropospheric Ozone Chemistrymentioning

confidence: 99%

“…Frost flowers can develop within a few hours when the ice surface temperature is much larger than that of the overlying air, as is the case for newly forming sea ice [Style and Worster, 2009]. Frost flowers last a few days at most, then disappear, covered with condensation (hoar), entrained in winds, covered by snowfall, or flooded with seawater [see Douglas et al, 2012;and references therein].…”

Section: Sea Ice Surface Bromine and Tropospheric Ozone Chemistrymentioning

confidence: 99%

See 1 more Smart Citation

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Vancoppenolle

Meiners

Michel

et al. 2013

Quaternary Science Reviews

217

215

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International audienceObservations from the last decade suggest an important role of sea ice in the global biogeochemical cycles, promoted by (i) active biological and chemical processes within the sea ice; (ii) fluid and gas exchanges at the sea ice interface through an often permeable sea ice cover; and (iii) tight physical, biological and chemical interactions between the sea ice, the ocean and the atmosphere. Photosynthetic micro-organisms in sea ice thrive in liquid brine inclusions encased in a pure ice matrix, where they find suitable light and nutrient levels. They extend the production season, provide a winter and early spring food source, and contribute to organic carbon export to depth. Under-ice and ice edge phytoplankton blooms occur when ice retreats, favoured by increasing light, stratification, and by the release of material into the water column. In particular, the release of iron - highly concentrated in sea ice - could have large effects in the iron-limited Southern Ocean. The export of inorganic carbon transport by brine sinking below the mixed layer, calcium carbonate precipitation in sea ice, as well as active ice-atmosphere carbon dioxide (CO₂) fluxes, could play a central role in the marine carbon cycle. Sea ice processes could also significantly contribute to the sulphur cycle through the large production by ice algae of dimethylsulfoniopropionate (DMSP), the precursor of sulphate aerosols, which as cloud condensation nuclei have a potential cooling effect on the planet. Finally, the sea ice zone supports significant ocean-atmosphere methane (CH₄) fluxes, while saline ice surfaces activate springtime atmospheric bromine chemistry, setting ground for tropospheric ozone depletion events observed near both poles. All these mechanisms are generally known, but neither precisely understood nor quantified at large scales. As polar regions are rapidly changing, understanding the large-scale polar marine biogeochemical processes and their future evolution is of high priority. Earth system models should in this context prove essential, but they currently represent sea ice as biologically and chemically inert. Palaeoclimatic proxies are also relevant, in particular the sea ice proxies, inferring past sea ice conditions from glacial and marine sediment core records and providing analogues for future changes. Being highly constrained by marine biogeochemistry, sea ice proxies would not only contribute to but also benefit from a better understanding of polar marine biogeochemical cycles

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Section: Sea Ice Surface Bromine and Tropospheric Ozone Chemistrymentioning

confidence: 99%

Section: Sea Ice Surface Bromine and Tropospheric Ozone Chemistrymentioning

confidence: 99%

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Vancoppenolle

Meiners

Michel

et al. 2013

Quaternary Science Reviews

217

215

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“…The surfaces of the three sites ranged from a few-day-old frost flower field with some surface snow (new ice pan), an ice pan with surface snow and an ice pan with 1-2-day-old frost flowers in which we cut an open hole through the ice which quickly froze over. Frost flowers are formed from water vapour above the sea ice into intricate ice crystal clusters (Simpson et al, 2007;Douglas et al, 2012a) that have the appearance of flowers on the surface. Brine enriched in sea salts are wicked up through the ice into these crystals.…”

Section: Mercury Measurements Over the Sea Icementioning

confidence: 99%

Atmospheric mercury over sea ice during the OASIS-2009 campaign

et al. 2013

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Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (PHg) were collected on the Beaufort Sea ice near Barrow, Alaska, in March 2009 as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) and OASIS-Canada International Polar Year programmes. These results represent the first atmospheric mercury speciation measurements collected on the sea ice. Concentrations of PHg averaged 393.5 pg m⁻³ (range 47.1–900.1 pg m⁻³) and RGM concentrations averaged 30.1 pg m⁻³ (range 3.5–105.4 pg m⁻³) during the two-week-long study. The mean concentration of GEM during the study was 0.59 ng m⁻³ (range 0.01–1.51 ng m⁻³) and was depleted compared to annual Arctic ambient boundary layer concentrations. It is shown that when ozone (O₃) and bromine oxide (BrO) chemistry were active there is a positive linear relationship between GEM and O₃, a negative one between PHg and O₃, a positive correlation between RGM and BrO, and none between RGM and O₃. For the first time, GEM was measured simultaneously over the tundra and the sea ice. The results show a significant difference in the magnitude of the emission of GEM from the two locations, with significantly higher emission over the tundra. Elevated chloride levels in snow over sea ice are proposed to be the cause of lower GEM emissions over the sea ice because chloride has been shown to suppress photoreduction processes of RGM to GEM in snow. Since the snowpack on sea ice retains more mercury than inland snow, current models of the Arctic mercury cycle may greatly underestimate atmospheric deposition fluxes because they are based predominantly on land-based measurements. Land-based measurements of atmospheric mercury deposition may also underestimate the impacts of sea ice changes on the mercury cycle in the Arctic. The predicted changes in sea ice conditions and a more saline future snowpack in the Arctic could enhance retention of atmospherically deposited mercury and increase the amount of mercury entering the Arctic Ocean and coastal ecosystems

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“…Atmospheric mercury depletion events provide a mechanism for rapid deposition of substantial amounts of mercury (as RGM oxidised from GEM) from the atmosphere to frozen surfaces during polar sunrise, [236][237][238][239][240][241][242][243][244] and have been hypothesised to contribute significantly to the high Hg levels in some Arctic biota. [245] In contrast, it is now well established that the Hg deposited during AMDEs can be readily re-emitted from the snowpack during winter conditions following AMDEs [7,16,25,80,101,187,241,[246][247][248] and during snow metamorphism and melt.…”

Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

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123

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Frost flowers growing in the Arctic ocean‐atmosphere–sea ice–snow interface: 1. Chemical composition

Cited by 72 publications

References 98 publications

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Atmospheric mercury over sea ice during the OASIS-2009 campaign

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

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