Climate versus geological controls on glacial meltwater micronutrient production in southern Greenland

Aciego, S.; Stevenson, Emily; Arendt, Carli A.

doi:10.1016/j.epsl.2015.05.017

Cited by 35 publications

(51 citation statements)

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“…Seasonal Fe limitation has however been found in parts of the high latitude North Atlantic (Nielsdottir et al, 2009;Ryan-Keogh et al, 2013). As high concentrations of dissolved and particulate Fe have been reported in meltwater from the Greenland Ice Sheet (Statham et al, 2008;Bhatia et al, 2013b;Hawkings et al, 2014) and glaciers around parts of Antarctica have been demonstrated to supply Fe to adjacent polynyas Sherrell et al, 2015), there is a clear interest in determining whether or not increasing volumes of meltwater discharge from Greenland could affect Fe supply to offshore marine ecosystems (Yde et al, 2014;Aciego et al, 2015;Hopwood et al, 2015). As most calved ice melts within this fjord (Bendtsen et al, 2015), the summer outflow of the low salinity surface layer along Godthåbsfjord is the most likely direct export mechanism for the particulate and dissolved Fe in meltwater to coastal seas.…”

Section: Fe Input and Potential Export To Coastal Seasmentioning

confidence: 99%

Seasonal Changes in Fe along a Glaciated Greenlandic Fjord

et al. 2016

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Greenland's ice sheet is the second largest on Earth, and is under threat from a warming Arctic climate. An increase in freshwater discharge from Greenland has the potential to strongly influence the composition of adjacent water masses with the largest impact on marine ecosystems likely to be found within the glaciated fjords. Here we demonstrate that physical and chemical estuarine processes within a large Greenlandic fjord are critical factors in determining the fate of meltwater derived nutrients and particles, especially for non-conservative elements such as Fe. Concentrations of Fe and macronutrients in surface waters along Godthåbsfjord, a southwest Greenlandic fjord with freshwater input from six glaciers, changed markedly between the onset and peak of the meltwater season due to the development of a thin (<10 m), outflowing, low-salinity surface layer. Dissolved (<0.2 µm) Fe concentrations in meltwater entering Godthåbsfjord (200 nM), in freshly melted glacial ice (mean 38 nM) and in surface waters close to a land terminating glacial system (80 nM) all indicated high Fe inputs into the fjord in summer. Total dissolvable (unfiltered at pH <2.0) Fe was similarly high with concentrations always in excess of 100 nM throughout the fjord and reaching up to 5.0 µM close to glacial outflows in summer. Yet, despite the large seasonal freshwater influx into the fjord, Fe concentrations near the fjord mouth in the out-flowing surface layer were similar in summer to those measured before the meltwater season. Furthermore, turbidity profiles indicated that sub-glacial particulate Fe inputs may not actually mix into the outflowing surface layer of this fjord. Emphasis has previously been placed on the possibility of increased Fe export from Greenland as meltwater fluxes increase. Here we suggest that in-fjord processes may be effective at removing Fe from surface waters before it can be exported to coastal seas.

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Section: Fe Input and Potential Export To Coastal Seasmentioning

confidence: 99%

Seasonal Changes in Fe along a Glaciated Greenlandic Fjord

et al. 2016

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“…Each sample site is located directly at the outflow terminus of a Greenland ice sheet outlet glacier (between 12-40 km in length), and sits atop bedrock of varying ages and lithologies. Each glacial outflow was sampled during peak melt as inferred from local; climatological data (Aciego et al, 2015), in summary:…”

Section: Location Of Glacial Outletsmentioning

confidence: 99%

“…Samples were collected from five land terminating glaciers around the western and southern margin of the Greenland Ice sheet (Aciego et al, 2015), and the Saqqarliup Sermia (GIL) (Fig. 1).…”

Section: Location Of Glacial Outletsmentioning

confidence: 99%

“…Subglacial water was filtered using a Masterflex modular peristaltic pump and a Perfluoroether (PFA) 47 mm filtration unit (Savillex). Hydrophobic Polyvinylidene fluoride Aciego et al (2015), see text for further lithological details. (b) The Qoorqup Sermia (GNR) rests on part of the Garder Intrusive Complex but the ice sheet is primarily resting on granite/granodiorite (1.8 Ga).…”

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confidence: 99%

“…The dissolved and suspended loads of glacial outflow are sampled from glaciers that vary in bedrock geology, size, and local seasonal climate (Aciego et al, 2015), in order to evaluate the hypothesis that the extent of chemical weathering controls the Fe isotopic composition of dissolved Fe. The data demonstrate that, within a given glacial system, the d…”

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confidence: 99%

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The iron isotopic composition of subglacial streams draining the Greenland ice sheet

Stevenson

Fantle

Das

et al. 2017

Geochimica et Cosmochimica Acta

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High export of dissolved silica from the Greenland Ice Sheet

Meire

Struyf

et al. 2016

Geophysical Research Letters

110

151

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Silica is an essential element for marine life and plays a key role in the biogeochemistry of the ocean. Glacial activity stimulates rock weathering, generating dissolved silica that is exported to coastal areas along with meltwater. The magnitude of the dissolved silica export from large glacial areas such as the Greenland Ice Sheet is presently poorly quantified and not accounted for in global budgets. Here we present data from two fjord systems adjacent to the Greenland Ice Sheet which reveal a large export of dissolved silica by glacial meltwater relative to other macronutrients. Upscaled to the entire Greenland Ice Sheet, the export of dissolved silica equals 22 ± 10 Gmol Si yr−1. When the silicate‐rich meltwater mixes with upwelled deep water, either inside or outside Greenland's fjords, primary production takes place at increased silicate to nitrate ratios. This likely stimulates the growth of diatoms relative to other phytoplankton groups.

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Climate versus geological controls on glacial meltwater micronutrient production in southern Greenland

Cited by 35 publications

References 50 publications

Seasonal Changes in Fe along a Glaciated Greenlandic Fjord

Seasonal Changes in Fe along a Glaciated Greenlandic Fjord

The iron isotopic composition of subglacial streams draining the Greenland ice sheet

High export of dissolved silica from the Greenland Ice Sheet

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