|Standing on the glacier at Borup Fiord Pass and looking down-valley (Photo: John Spear)|
Borup Fiord Pass. I've said that name so many times that it almost feels like the name of a good friend. Last summer I had the opportunity to visit this remote place on the planet, far north of the northernmost cities of North America. The experience was incredible and something that I will cherish forever. My research team and I spent two weeks at Borup Fiord Pass, and when we left we brought back the samples that I'm now studying to better understand the relationships between living organisms and the chemical element sulfur.
Borup Fiord Pass is a valley in the Canadian High Arctic where yellow staining of the surface of a glacier is caused by large deposits of sulfur in its elemental form. This site gives us the opportunity to study the chemical and biological cycling of sulfur through various forms in a unique icy environment. Borup Fiord Pass also gives us a chance to study some of the biological processes we might expect to find on icy worlds with subsurface oceans, such as Jupiter's moon Europa, if life ever came to exist there.
|Europa, one of the most intriguing places in the solar system (NASA)|
Watch out where those huskies go...Borup Fiord Pass is located on Ellesmere Island, very near the North Pole, at the northern extreme of the Canadian territory of Nunavut. To get an idea of where this is, if you hold up a globe and point the North Pole directly toward yourself, then Borup Fiord Pass will be within the first 10 degrees of latitude from the center:
|Looking at the world with the North Pole at the center|
Benoit Beauchamp, of the University of Calgary, was the first person to see the yellow staining on the glacier at Borup. At least, that's what I've been told. There are military flights that pass overhead quite often. I wouldn't be too surprised if one of the pilots of a military plane was flying low and happened to see some large yellow patch on the white of the ice. Maybe that pilot thought, "huh, that's interesting." Or maybe some explorer decades ago chanced upon a glacier with a yellow icing that smelled of hydrogen sulfide, but the same explorer didn't see need to note the occurrence.
We really don't know how long this yellow staining has been happening, though we know it's been active since Benoit first noticed it during a helicopter fly-over in 1988. Once Steve Grasby, a geochemist with the Geological Survey of Canada and my collaborator, learned from Benoit about the yellow coloration on top of the glacier, he knew something special was happening and had to check it out.
|Steve Grasby sampling a sulfur deposit on one his earliest trips to Borup Fiord Pass|
The sulfur is deposited by springs that emerge on the glacier and which carry high levels of sulfide, the most electron-rich (reduced) form of sulfur, with a formal oxidation state of -2. In considering the chemical composition of the spring fluids and the isotopes of sulfur at the site, Steve Grasby and his colleagues determined that the sulfide is likely derived from sedimentary sulfate deep in the subsurface. Sulfate is the most electron-poor (oxidized) form of sulfur (since the sulfur atom in a sulfate molecule shares it's electrons with four oxygen atoms, giving the sulfur a formal oxidation state of +6). The transition from sulfate to sulfide implies that there must be microorganisms somewhere below the glacier which are using sulfate reduction (making sulfur more electron-rich) for their metabolisms.
After sulfur in groundwater has been processed by organisms in the subsurface, it then flows up through the glacier or along its base and emerges as springs at the surface. Many years, the springs are still quite active when researchers have arrived to investigate. Last summer, in 2014, there was no apparent spring activity, but rather an earlier spring had deposited a large sheet of sulfide-rich ice.
Where this icing dropped over the sides of a small canyon, we called the deposit "Sulfur Falls" (see image below). Near the glacier, in the middle of the icing, was a large circular structure that we called "The Blister". This structure may be the remnant of a sulfur-rich plume which had burst its way out from the subsurface and could possibly have formed the icing.
|This is me kneeling on a pile of glacial till in front of the toe of the glacier at Borup Fiord Pass. The yellow coloration of the ice behind me is caused by the deposition of elemental sulfur at this site. (Photo: John Spear)|
The sulfide-rich water and ice that forms at the surface then provides the material for the oxidation of sulfide (stripping of electrons from sulfur) to form elemental sulfur (sulfur with a formal oxidation state of 0 and which only forms bonds with other sulfur atoms). Elemental sulfur forms one of the most beautiful minerals on Earth:
|Elemental sulfur: the mineral is yellow in solid state, |
turns blood red when melted, and burns a bright blue (Image: Volty)
Another interesting question comes from the presence of the yellow sulfur itself. Given the chemistry of the fluid at the ice surface and the presence of oxygen from the atmosphere, the sulfur should be oxidized the whole way to sulfate, yet the yellow staining persists throughout the summer (at least until the snow begins to fall at this site). Much of my work is now focused on quantifying the different chemical forms of sulfur at Borup Fiord Pass. Expect more posts from me in the near future that details some of the various types of instruments and methods that I'm using in this endeavor.
|Using the Field Microsensor Multimeter from Unisense to measure sulfide (Image: Alexis Templeton)|
The Connection to EuropaThere's been a lot of buzz in the press and social media lately regarding Europa. Europa is one of the four Galilean Moons of Jupiter and is definitely one of the more intriguing places in our solar system for astrobiologists. Europa bears a deep subsurface ocean, and that ocean might have been in recent communication with the surface. If life ever came about in the ocean of Europa, we might have the potential to find signs of such life near the surface of that moon. We're now working on the next spacecraft that will explore Europa.
Europa's awesome surface textures and deep subsurface ocean are enough to scientifically justify a mission to that moon, but the possibility for life detection in materials at Europa have bolstered scientific and public support together and now it looks like we might soon see a Europa mission on its way to Jupiter. For us to better understand what signs of life we may find on Europa, it's a good idea to study life in icy environments here on Earth. Places like Lake Vostok and Blood Falls in Antarctica and Borup Fiord Pass, my field site, in the Arctic can aide in this type of research. Indeed, Borup Fiord Pass has gotten its fair share of press as a Europa analogue site. Here are articles from Wired, Space.com, Popular Science, and CBC News that report on the importance of Borup Fiord Pass in our search for life on Europa.
With Lake Vostok and other ice-covered Antarctic lakes, as well as some recent research on a drilling project to study the organisms living under the Ross Ice Shelf, we can explore ecosystems in lakes and oceans deep below icy environments. Research in these areas may highlight the techniques we'll need if we ever want to get through the ice on Europa and explore the ocean below. However, that ice is very thick (probably at least 1 km but maybe more than 10 km in thickness), and it will take us a long time to build a spacecraft with the right technology to get down there. In the meantime, there's a lot that we have to learn about Europa's ocean and the possibility for signs of life to be found in the near-surface of the ice through an orbiter mission and our first lander mission. That's where our work at Borup Fiord Pass comes in. By studying the connection of subsurface microbial processes to the chemical and biology processes that occur where fluids make their way through the ice and to the surface, we might be able to highlight some key signs of life to look for near the Europan surface.
I was recently at NASA's Ames Research Center for the Workshop on the Potential for Finding Life in a Europa Plume. There are a lot of us who are now trying to figure out what the best instrumentation is to send to Europa to capture signs of life. You might have read recently about the potential discovery of water plumes coming out of Europa. Although some of us are highly skeptical of the data in that study, if there are water plumes at Europa, they may offer even more insight into the processes that are occurring in the subsurface ocean. Even if the plumes are not there, we still have a lot to learn with the mission that we'll be sending to Europa. If we can get data about the chemistry of the surface or, better yet, the near subsurface, then we may be able to find signs of life from the subsurface ocean. This of course requires that fluid from the ocean has made its way through the ice and to the near surface. There's a lot of "ifs" involved, but that's part of the fun of science.
In the coming months, I'll be writing up posts that detail the importance of sulfur for astrobiology as well as the importance of Borup Fiord Pass in our exploration of Europa (and other worlds). These are important topics for me, especially since they'll be included in my Ph.D. dissertation. Before I leave you, though, here's a sweet infographic from NASA regarding Europa, one of the most intriguing worlds in our solar system: