Sailors and explorers have reported seeing strange green icebergs in parts of Antarctica since the early 1900s.
The bizarre phenomenon has baffled scientists for more than a century - but now researchers believe they've solved the mystery.
A new study suggests the green hue is the result of iron oxides in rock dust from Antarctica’s mainland.
Researchers collected data during a 2016 voyage to the Amery Ice Shelf in East Antarctica.
They published the findings from their study 'Green Icebergs Revisited' in the Journal for Geophysical Research in January.
Arctic sailors and explorers have reported seeing strange green icebergs near parts of Antarctica since the early 20th century
An oceanographer who tested an ice core from Amery Ice Shelf found frozen sea water known as 'marine ice,' located near the bottom of the core, contained almost 500 times more iron than the glacial ice above
Scientists discovered large amounts of iron in the polar ice and theorized that 'foreign constituents' in seawater, particularly iron-oxide, can change its color.
'Previously, dissolved organic carbon (DOC) had been proposed to be responsible for the green color,' authors Stephen Warren, Collin Roesler, Richard Brandt, and Mark Curran explained in their findings.
'Subsequent measurements of low DOC values in green icebergs, together with the recent finding of large concentrations of iron in marine ice from the Amery Ice Shelf, suggest that the color of green icebergs is caused more by iron‐oxide minerals than by DOC.'
Icebergs that form from glacier ice that breaks off from the continent-sized Antarctic ice sheet can include frozen seawater collected at the glaciers' bases.
The green ice at the bottom of some ice bergs becomes visible when the icebergs occasionally capsize
Researchers with the Journal for Geophysical Research collected data from their study of the Amery Ice Shelf in East Antarctica during a 2016 voyage to the frozen continent
The scientists discovered large amounts of iron in the polar ice and theorized that 'foreign constituents' in seawater, particularly iron-oxide, can change its color.
That frozen sea water, known as marine ice, can contain organic and inorganic particles that can add shades of green to ice that normally comes in shades of blue or white.
The green ice at the bottom of the ice bergs becomes visible when the icebergs occasionally capsize.
Warren, the study's lead author, is a glaciologist at the University of Washington who has been studying green icebergs since 1988.
In his report, he recalled an oceanographer who tested an ice core from Amery Ice Shelf and found marine ice near the bottom of the core contained almost 500 times more iron than the glacial ice above.
Warren suspected the iron oxides were what was changing the marine ice from blue to green.
The study authors said the green marine ice contains iron that can help feed organisms like phytoplankton as the green icebergs float out into the ocean
The phenomenon isn't just noteworthy because of its beauty.
Marine ice contains iron carried by these glaciers, which could help feed organisms as they float deeper into the ocean.
'It’s like taking a package to the post office,' Warren said in a statement.
'The iceberg can deliver this iron out into the ocean far away, and then melt and deliver it to the phytoplankton that can use it as a nutrient.'
'We always thought green icebergs were just an exotic curiosity, but now we think they may actually be important,' he added.
The normally blue hue of icebergs is caused by the absorption of more red light than blue light.
The study authors said they want to sample more green icebergs to study their iron content.
Link hienalouca.com
https://hienalouca.com/2019/03/06/scientists-solve-the-mystery-of-rare-green-icebergs-seen-only-in-antarctica/
Main photo article Sailors and explorers have reported seeing strange green icebergs in parts of Antarctica since the early 1900s.
The bizarre phenomenon has baffled scientists for more than a century – but now researchers believe they’ve solved the mystery.
A new study suggests the green hue is the r...
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Dianne Reeves US News HienaLouca
https://i.dailymail.co.uk/1s/2019/03/06/02/10631830-6775869-image-a-33_1551840980492.jpg
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