Accidental Science: Seminar Sum-Ups

It is well known many scientific discoveries have been made by accident and the work Martin Sharp explained in a recent seminar I attended is no exception. Martin and his team have been working on on the Devon Ice Cap (Figure 1) supported by the University of Alberta. They began their investigations due to the lack of research within Canadian glaciology and choose the Devon Ice Cap purely as it was the closest in location to the support bay. It therefore provided the easiest and cheapest access, a lucky chance that has paid off!

Figure 1: Location of the Devon Ice Cap, Canada. Both in map (left) and satellite (right) image, covering an area of over 12,000km2, (Google Maps). 

 Martin presented his research findings in two parts concentrating first on the discovery of two hyper saline subglacial lakes under the Devon Ice Cap.
Note: Hypersaline subglacial lakes – A hypersaline lake is a body of water with significant salt concentrations and therefore has a higher salinity than ocean water so more than 3.5%. Subglacial implies the lake is under a glacial, ice cap or ice sheet. 

Evidence

There were four key lines of evidence Martin that led to the discovery:


- Radar Echo Sounding (RES) identified two areas of unusually high reflectivity.

- Relatively flat hydraulic heads calculated at each lake location

- Basal ice temperatures well below fresh water melting point

- Salt-bearing geology near the two lakes

RES

Radar surveys revealed over two topographic troughs bed reflectivity was especially high in these two areas in comparison to the surrounding area. A contact between ice and rock would lead to lower reflective sounds. This therefore led to the conclusion that water must contact the basal ice and indicates the presence of a subglacial lake in each of these two troughs. 

Hydraulic Head

To identify subglacial lakes the concept of a ‘flat’ hydraulic head is often used. Hydraulic head is the measure of pressure between the sub glacial water and overlying ice and if flat represent the ice is floating o the water so is evidence the water body is a sub glacial lake.  

Basal Ice Temperature

The basal ice temperatures measured were far lower (-18 to -30⁰C) than the melting point of fresh water and this indicates there must be high quantities of salt. Hyper salinity significantly decreases the freezing point and provides a reason for the unusually low temperatures.

Salt-bearing Geology

Despite the basal ice temperature evidence, it is also necessary to explain where this extra salt content could originate from. The team carried out geological mapping of the area from published data and drill cores. A formation, Bay Fiord Formation is present and inferred to lie surrounding the two troughs. This formation includes a bedded salt sequence which provides a suitable supply of salt through dissolution to create hyper saline water bodies.


Figure 2: Location of the two troughs where the hypothesised hypersaline subglacial lakes (T1&T2) lie. Highlighted in yellow is the inferred presence of the Bay Fiord Formation which could provide the quantities of salt required to create hyper salinity within the water bodies, (Rutishauser et al., 2018).

 These four lines of evidence provide conformation that two subglacial hypersaline lakes lie in bedrock troughs under the Devon Ice Cap in Canada.

Martin and his team are keen to do further research with geophysical work and carry out sterile drilling to gain information on the water chemistry. The formation and origin of the lakes are still unknown, so this research could provide important insights. One potential hypothesis detail that the area may have become fully deglaciated at one point and as ice formed it concentrated the salinity. Taylor Glacier in Antarctica is the only other subglacial lake with similar features and microbial life has been found. Martin and his team therefore suggest that microbial life could also be present in the subglacial lakes beneath the Devon Ice Cap. This provides another important reason further research should be carried out and reveals an interesting link that the Martian polar ice caps could or did also harbour similar lakes and maybe even life.


Other Research

Sverdup Meltwater Tunnels

The second part of Martin’s seminar showed some fascinating pictures from their time exploring tunnels under Sverdup Glacier in Arctic Canada. From snow melting the water can carve pools and create tunnels underneath glaciers. Some of the tunnels they explored were up to 2m high and air temperatures of +1⁰C allowing evaporation and condensation processes to create impressive ice crystals. The chemistry of the basal ice revealed interesting indication that microbes must be present using the nutrients within the ice and channel water that flowed through the tunnels. Martin hopes more research can be done in this area to better understand the complex subglacial drainage system and the life forms that could be present.

Figure 3: Example of a tunnel carved by meltwater under a glacier, The Matanuska Glacier, Southcentral Alaska.

Wider Context 

The work that Martin does is not just imperative to decipher if unique life forms live in these hostile environments here and on Mars, but it is also so important in this time of global change. Ice Caps throughout the globe are rapidly evolving and it is so important to understand what we can to mitigate and predict their future responses as they adjust to our new warming world. His work also shows just how interesting accidental science can be!


Meg
Links you might be interested in:

The paper published by Martin and his team in Science Advances -

Rutishauser, A., Blankenship, D.D., Sharp, M., Skidmore, M.L., Greenbaum, J.S., Grima, C., Schroeder, D.M., Dowdeswell, J.A. and Young, D.A., 2018. Discovery of a hypersaline subglacial lake complex beneath Devon Ice Cap, Canadian Arctic. Science advances, 4(4), p.eaar4353.

Some of Martin’s other work on Ice Caps –
https://www.scientia.global/professor-martin-sharp-melting-ice-understanding-the-shrinking-arctic-ice-caps/







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