Blood Falls: Origins and Life in Subglacial Environments

Blood Falls sitting at the terminus of Taylor Glacier on GlacierHub
Blood Falls sitting at the terminus of Taylor Glacier, spilling its bright-red discharge onto Lake Bonney (Source: German Aerospace Center DLR/Flickr).

Amid Antarctica’s vast stretches of glittering white snow and ethereal blue glacier ice is the famous Blood Falls. Situated at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Blood Falls, which is an iron-rich, hypersaline discharge, spews bold streaks of bright-red brine from within the glacier out onto the ice-covered surface of Lake Bonney.

Australian geologist Griffith Taylor was the first explorer to happen upon Blood Falls in 1911, during one of the earliest Antarctic expeditions. At the time, Taylor (incorrectly) attributed the color to the presence of red algae. The cause of this color was shrouded in mystery for nearly a century, but we now know that the iron-rich liquid turns red when it breaches the surface and oxidizes––the same process that gives iron a reddish hue when it rusts.

The discharge from Blood Falls is the subject of a new study, published in the Journal of Geophysical Research: Biogeosciences, researchers sought to discern the origin, chemical composition, and life-sustaining capabilities of this subglacial brine. Lead author W. Berry Lyons of The Ohio State University and his co-researchers determined that the brine “is of marine origin that has been extensively altered by rock-water interactions.”  

Researchers used to believe that to be that Taylor Glacier was frozen solid from the surface to its bed. But as measuring techniques have advanced over time, scientists have been able to detect huge amounts of hypersaline liquid water at temperatures that are below freezing underneath the glacier. The large quantities of salt in hypersaline water enable the water to remain in liquid form, even below zero degrees Celsius.

IceMole at Taylor Glacier on GlacierHub
Overhead view of the IceMole, as it gradually descends into Taylor Glacier, melting ice as it goes (Source: German Aerospace Center DLR/Flickr).

Seeking to expand on this recent discovery, Lyons and his co-researchers conducted the first direct sampling of brine from Taylor Glacier using the IceMole. The IceMole is an autonomous research probe that clears a path by melting the ice that surrounds it, collecting samples along the way. In this study, the researchers sent the IceMole through 17 meters of ice to reach the brine beneath Taylor Glacier.

The brine samples were analyzed to obtain information on its geochemical makeup, including ion concentrations, salinity, and other dissolved solids. Based on the observed concentrations of dissolved nitrogen, phosphorus, and carbon, the researchers concluded that Taylor Glacier’s subglacial environment has, along with high iron and sulfate concentrations, active microbiological processes––in other words, the environment could support life.

To determine the origin and evolution of Taylor Glacier’s subglacial brine, Lyons and his co-researchers pondered other studies’ conclusions in comparison to their results. They decided the most plausible explanation was that the subglacial brine came from an ancient time period when Taylor Valley was likely flooded by seawater, though they did not settle on an exact time estimate.

An aerial view of Taylor Glacier and the location of Blood Falls on GlacierHub
An aerial view of Taylor Glacier and the location of Blood Falls (Source: Wikimedia Commons).

In addition, they found that the brine’s chemical composition was much different than that of modern seawater. This suggested that as the brine was transported throughout the glacial environment over time, weathering contributed to significant alterations in the chemical composition of the water.

This study provides insights not only for subglacial environments on Earth but also potentially to other bodies within our solar system. Seven bodies, including Europa (one of Jupiter’s moons), Enceladus and Titan (two of Saturn’s moons), Pluto, and Mars are thought to harbor sub-cryospheric oceans.

Lyons and his co-researchers concluded that this subglacial brine environment likely is conducive to life. The ability of sub-cryospheric environments such as this one to support life on Earth hints at an increased possibility of finding life in similar environments elsewhere in our solar system.

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Roundup: Ice Sheets, Cryoconite Holes and Turbulent Heat Fluxes

Late Quaternary Meltwater Pulses and Sea Level Change

From Journal of Quaternary Science: “After the Last Glacial Maximum (LGM) global mean sea level (GMSL) rise was characterized by rapid increases over short (decadal to centennial) timescales superimposed on a longer term secular rise and these have been termed meltwater pulses (MWPs). In this paper we review the timing, impact and nature of these and the effects of rapid drainage of large post‐glacial MWPs into the world’s oceans. We show that drainage of the known post‐glacial lakes in total produced less than around 1.2 m of the 125 m of GMSLR since the LGM.”

Read more about the article here.

Location of the Last Glacial Maximum and Lateglacial lakes (Source: Stephan Harrison, David E. Smith, Neil F. Glasser).

 

Island Biogeography of Cryoconite Hole Bacteria in Antarctica

From Frontier in Ecology and Evolution: “Cryoconite holes are holes in a glacier’s surface caused by sediment melting into the glacier. These holes are self-contained ecosystems that include abundant bacterial life within their sediment and liquid water, and have recently gained the attention of microbial ecologists looking to use cryoconite holes as “natural microcosms” to study microbial community assembly. This article applies models of island ecosystems to these holes because they are very much like islands in the sea, surrounded by a barrier to entry. ”

Read the details of the paper here.

Cryoconite Holes (Source: Alan Grinberg/Flickr).

 

Turbulent Heat Fluxes in Qilian Mountains, China

From JGR Atmospheres:” A study of using the bulk method to quantify the turbulent air flow and sublimation/condensation over glacier in August-One Glacier, Qilian Mountains, China. This article addresses the patterns of warming at different wind speeds. We tried to acquire reliable varying and intrinsic aerodynamic roughness length for momentum through its parametric analysis.”
For more details, click here.
Eight-One Glacier (Source: Yen L./Flickr).

 

 

 

 

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Geochemical Evolution of Meltwater from Glacier Snow to Proglacial Lake

Glaciers around the world are making headlines for their rapid retreat due to warming. Unlike some of these glaciers, however, dry valley glaciers, while accumulating only about 10 cm of snow annually, are neither retreating nor warming. Sarah Fortner, a geochemistry professor at Wittenberg University in Ohio, examined the meltwater of Canada Glacier, a dry valley glacier located in the Taylor Valley of Antarctica, and published a paper focused on two of its proglacial streams, Anderson Creek and Canada Stream.

Canada Glacier flowing into the Taylor Valley, Antarctica (Source: Anthony Powell).

Melting of glaciers develops an important part of a glacier’s anatomy known as “supraglacial streams,” which are conduits of water on top of glaciers. These supraglacial streams often become a source of water for “proglacial streams,” like the Anderson Creek and Canada Stream, narrow channels of rivers that issue from glaciers supply water to lakes located below the glaciers.

Fortner studied the meltwater of Canada Glacier during the 2001 to 2002 austral summer in the southern hemisphere (from November to March) and the contribution of the proglacial stream and glacial surface to water in Lake Hoare, which is located in front of Canada Glacier.

In her study, Fortner determines the crucial role of the wind in redistributing the geochemistry of the glacial surface as well as the two proglacial streams. By looking at the geochemistry of the two proglacial streams and the role of the wind in bringing valley sediments to the supraglacial and ultimately proglacial streams, Fortner found that the glaciers that contributed to the proglacial lakes are not dilute like glacier snow.

Large pond formed from supraglacial melt on the surface of Canada Glacier. (Source: Fortner)

Contrary to expectations, the chemistry between the two streams was quite different. “While they are roughly five miles apart, they were very different,” she told GlacierHub. “Located on the east side of the glacier, Canada Stream was teaming with life, with multiple mosses, lichen, algae, and invertebrates. If you were to press your hand into these, it would feel like a sponge. On the west side of the glacier, Anderson Creek looks barren in comparison. There is life in the stream, but not as abundant or diverse as the Canada Stream.”

In an attempt to find the source of the difference, Fortner and a team of scientists sampled water from supraglacial channels with high discharge for chemical analysis. Through this analysis, Fortner aimed to map the evolution of the chemicals in the meltwater at Canada Glacier from unmelted glacier snow to supraglacial streams to proglacial streams and finally to Lake Hoare located in front of the glacier.

Taylor Valley and Lake Hoare (Source: 77DegreesSouth).

With the chemical mass balance analysis of the samples from the glacier, Fortner first wanted to see whether the chemical composition of the supraglacial stream would be diluted like the unmelted glacier snow, their primary precipitation. According to Fortner, unmelted glacier snow would naturally be very dilute, with a low concentration of any chemical solute, and we would expect the same level of chemical concentration from the supraglacial streams, located on top of the glacier body itself and created as a result of glacier snow melting. However, she found that supraglacial streams were rich in major ions like calcium, sodium, and sulfate. 

“This begins to highlight the importance of wind-blown sediment as control of water chemistry in these Antarctic ecosystems,” Fortner said.

In her paper, she explains that the strong west to east Föhn wind (Foehn wind), a parcel of dry and warm air moving down the lee (downwind side) of the mountain, brought sediments from the floor of Taylor Valley, abundant with carbonate ( CO3(2-)) and gypsum (CaH4O6S) minerals, which are the sources of the high calcium (Ca2+) and sulfate ion (SO2-4) found in the supraglacial streams. In short, the wind delivered sediment that influenced the chemistry of the streams on the surface of the glacier.

Diagram of Föhn wind (Source: ipfs).

“Both sides of the valley floor contributed to the sediment received on the glacier surface which explained major chemical differences found in supraglacial and proglacial streams versus the original unmelted snow. It is also clear that the Föhn wind coming off of the ice sheet had the greatest influence on depositing chemistry,” Fortner explained.

Furthermore, the west to the east direction of the wind causes a difference in chemical composition between the proglacial streams in the western and eastern sides of Canada Glacier, preferentially depositing more sulfate in the western proglacial streams (Anderson Creek) than in the eastern proglacial streams (Canada Stream).

“As a result of the west to east wind, supraglacial streams flowing into Anderson Creek have much higher concentrations of both calcium and sulfate than supraglacial streams flowing into Canada Stream,” Fortner explained.

Map of the Ross Sea. Lake Hoare is located within the Taylor Valley, showing its proximity to Ross Sea. (Sources: USGSantarctic.eu).

The chemical deliveries from the stream channel to the proglacial lake is crucial to examine, as Anderson Creek contributes over 40 percent of the water to Lake Hoare, the final recipient of the meltwater from Canada Glacier, during the low-melt season. However, Fortner said it is just as important to examine the chemical deliveries from the glacial surface (direct runoff).

“While one would think streams would deliver far more chemistry, as glaciers and their direct runoff are typically dilute, glacier surface can be just as important source of chemistry because of the low accumulation and wind delivered sediment,” she added.

Dry valley glaciers are unique in that the glacier surface is an important contributor of chemistry to downstream ecosystems. Unlike many other glaciers, it isn’t just about chemistry from stream channels, but also about glacier surfaces. If more melt continues in response to the wind, this could result in potential changes in the chemical delivery into Lake Hoare. Furthermore, such changes can extend to the continental outline of Antarctica into Ross Sea, the southern extension of the Pacific Ocean.

 

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