Large flux of iron from the Amery Ice Shelf marine ice to Prydz Bay, East Antarctica

Herráiz‐Borreguero, Laura; Lannuzel, Delphine; Merwe, Pier van der; Treverrow, Adam; Pedro, J. B.

doi:10.1002/2016jc011687

Cited by 63 publications

(67 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While low‐latitude environments of the Southern Ocean may receive atmospheric inputs of iron, coastal Antarctica generally does not (Heywood et al, ), except for places such as McMurdo Sound which is in close proximity to the dry valleys and Mount Erebus volcano (de Jong et al, ). The main sources of iron to coastal Antarctica are (1) melting ice shelves, glaciers, and icebergs, particularly if marine ice is present (Herraiz‐Borreguero et al, ; Lin et al, ); (2) upwelled iron‐rich mCDW interacting with Fe‐rich sediments (de Jong et al, ; Measures et al, ; Sherrell et al, ); and (3) sea ice (Lannuzel, Vancoppenolle, et al, ). We examine each of these sources in this and the following two sections.…”

Section: Discussionmentioning

confidence: 99%

Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas

et al. 2019

Self Cite

View full text Add to dashboard Cite

In the Southern Ocean, polynyas exhibit enhanced rates of primary productivity and represent large seasonal sinks for atmospheric CO2. Three contrasting east Antarctic polynyas were visited in late December to early January 2017: the Dalton, Mertz, and Ninnis polynyas. In the Mertz and Ninnis polynyas, phytoplankton biomass (average of 322 and 354 mg chlorophyll a (Chl a)/m2, respectively) and net community production (5.3 and 4.6 mol C/m2, respectively) were approximately 3 times those measured in the Dalton polynya (average of 122 mg Chl a/m2 and 1.8 mol C/m2). Phytoplankton communities also differed between the polynyas. Diatoms were thriving in the Mertz and Ninnis polynyas but not in the Dalton polynya, where Phaeocystis antarctica dominated. These strong regional differences were explored using physiological, biological, and physical parameters. The most likely drivers of the observed higher productivity in the Mertz and Ninnis were the relatively shallow inflow of iron‐rich modified Circumpolar Deep Water onto the shelf as well as a very large sea ice meltwater contribution. The productivity contrast between the three polynyas could not be explained by (1) the input of glacial meltwater, (2) the presence of Ice Shelf Water, or (3) stratification of the mixed layer. Our results show that physical drivers regulate the productivity of polynyas, suggesting that the response of biological productivity and carbon export to future change will vary among polynyas.

show abstract

Section: Discussionmentioning

confidence: 99%

Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Seasonal deficits in mixed‐layer TCO 2 were attributed to a combination of sea ice melt and biological production (Roden et al, ), similar to the drivers of TCO 2 depletion in the Dalton Polynya, resulting in low surface water f CO 2 and an air‐to‐sea flux of CO 2 . Recent studies in Prydz Bay propose that glacial meltwater from the nearby Amery Ice Shelf may bring a large, bioavailable source of dissolved iron from marine‐accredited ice beneath the ice shelf, locally enhancing primary productivity (Herraiz‐Borreguero et al, ). In contrast to the glacial meltwaters introduced by the intrusions of mCDW beneath the TIS and MUIS (warm‐regime) to Dalton Polynya, the glacial meltwaters introduced into Prydz Bay are the result of intrusions of cold Dense Shelf Water beneath the Amery Ice Shelf (cold regime; Silvano et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…In contrast to the glacial meltwaters introduced by the intrusions of mCDW beneath the TIS and MUIS (warm‐regime) to Dalton Polynya, the glacial meltwaters introduced into Prydz Bay are the result of intrusions of cold Dense Shelf Water beneath the Amery Ice Shelf (cold regime; Silvano et al, ). The resulting outflow of supercooled ISW can entrain subglacial dissolved iron into the marine ice layer beneath the ice shelf and, upon basal melting, can deliver dissolved iron onto the continental shelf in concentrations up to 4 orders of magnitude higher than typical Southern Ocean waters (Herraiz‐Borreguero et al, ). In the analysis by Arrigo et al (), the input of basal meltwater by nearby ice shelves can explain almost 60% of the variance in mean Chl a concentrations in Antarctic polynyas.…”

Section: Discussionmentioning

confidence: 99%

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Arroyo¹,

Shadwick

Tilbrook

2019

JGR Oceans

View full text Add to dashboard Cite

The carbonate chemistry in the Dalton Polynya in East Antarctica (115°–123°E) was investigated in summer 2014/2015 using high‐frequency underway measurements of CO2 fugacity (fCO2) and discrete water column measurements of total dissolved inorganic carbon (TCO2) and total alkalinity. Air‐sea CO2 fluxes indicate this region was a weak net source of CO2 to the atmosphere (0.7 ± 0.9 mmol C m−2 day−1) during the period of observation, with the largest degree of surface water supersaturation (ΔfCO2 = +45 μatm) in ice‐covered waters near the Totten Ice Shelf (TIS) as compared to the ice‐free surface waters in the Dalton Polynya. The seasonal depletion of mixed‐layer TCO2 (6 to 51 μmol/kg) in ice‐free regions was primarily driven by sea ice melt and biological CO2 uptake. Estimates of net community production (NCP) reveal net autotrophy in the ice‐free Dalton Polynya (NCP = 5–20 mmol C m−2 day−1) and weakly heterotrophic waters near the ice‐covered TIS (NCP = −4–0 mmol C m−2 day−1). Satellite‐derived estimates of chlorophyll a (Chl a) and sea ice coverage suggest that the early summer season in 2014/2015 was anomalous relative to the long‐term (1997–2017) record, with lower surface Chl a concentrations and a greater degree of sea ice cover during the period of observation; the implications for seasonal primary production and air‐sea CO2 exchange are discussed. This study highlights the importance of both physical and biological processes in controlling air‐sea CO2 fluxes and the significant interannual variability of the CO2 system in Antarctic coastal regions.

show abstract

“…These dFe sources are thought to include seafloor sediments and benthic detritus [ Hatta et al ., ; Marsay et al ., ], melting sea ice [ Lannuzel et al ., ; Schallenberg et al ., ; Sedwick and DiTullio , ], melting glacial ice and icebergs [ Gerringa et al ., ; Lin et al ., ; Raiswell et al ., ], subglacial meltwaters [ Death et al ., ; Herraiz‐Borreguero et al ., ], upwelling Circumpolar Deep Water [ McGillicuddy et al ., ; Prézelin et al ., ; Sedwick et al ., ], and deposition of iron‐bearing aerosols [ Cassar et al ., ; Edwards and Sedwick , ; Winton et al ., ]. In addition, relatively high concentrations of particulate iron (pFe) have been measured in surface waters over the Antarctic continental shelves [ Coale et al ., ; Fitzwater et al ., ; Planquette et al ., ], although the potential availability of this iron pool to phytoplankton, either directly or via conversion to dFe, remains to be established.…”

Section: Introductionmentioning

confidence: 99%

Distributions, sources, and transformations of dissolved and particulate iron on the Ross Sea continental shelf during summer

et al. 2017

View full text Add to dashboard Cite

We report water column dissolved iron (dFe) and particulate iron (pFe) concentrations from 50 stations sampled across the Ross Sea during austral summer (January–February) of 2012. Concentrations of dFe and pFe were measured in each of the major Ross Sea water masses, including the Ice Shelf Water and off‐shelf Circumpolar Deep Water. Despite significant lateral variations in hydrography, macronutrient depletion, and primary productivity across several different regions on the continental shelf, dFe concentrations were consistently low (<0.1 nM) in surface waters, with only a handful of stations showing elevated concentrations (0.20–0.45 nM) in areas of melting sea ice and near the Franklin Island platform. Across the study region, pFe associated with suspended biogenic material approximately doubled the inventory of bioavailable iron in surface waters. Our data reveal that the majority of the summertime iron inventory in the Ross Sea resides in dense shelf waters, with highest concentrations within 50 m of the seafloor. Higher dFe concentrations near the seafloor are accompanied by an increased contribution to pFe from authigenic and/or scavenged iron. Particulate manganese is also influenced by sediment resuspension near the seafloor but, unlike pFe, is increasingly associated with authigenic material higher in the water column. Together, these results suggest that following depletion of the dFe derived from wintertime convective mixing and sea ice melt, recycling of pFe in the upper water column plays an important role in sustaining the summertime phytoplankton bloom in the Ross Sea polynya.

show abstract

Large flux of iron from the Amery Ice Shelf marine ice to Prydz Bay, East Antarctica

Cited by 63 publications

References 76 publications

Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas

Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas

Summer Carbonate Chemistry in the Dalton Polynya, East Antarctica

Distributions, sources, and transformations of dissolved and particulate iron on the Ross Sea continental shelf during summer

Contact Info

Product

Resources

About