Wilson-Piedemont Glacier

Monday was a spectacular day and we had no trouble getting out to collect samples on the Wilson-Piedemont Glacier. WP is a broad coastal glacier at the northwestern most extent of McMurdo Sound. Because the wind often blows from the southeast the WP is ideally located to collect small particles eroded from the surface of sea ice in the Sound. WP, like other glaciers, is almost entirely fresh. Researchers have shown that glaciers do contain small amounts of sea salts however, and there is further evidence that some of these salts may come from frost flowers. Glacial sea salts are just a little bit depleted in sulfate relative to the other ions, suggesting that the salt must have come from ice so cold that it contained no sodium sulfate (see “Pass the salt” for a further explanation). Frost flowers, saline snow, and other similar cold salty features at the sea ice surface seem like a logical source for this salt.

Our task at WP was to collect enough ice to determine whether bacteria and bacterial genes present within frost flowers might also be present within glacial ice. There aren’t a lot of bacteria within glacial ice – maybe 1,000 bacteria per milliliter compared to 100 times that many for sea ice – so we have to collect a lot of it. It took two helicopter flights to get us and all of our sampling containers to and from the glacier. We didn’t count the number of ice cores we pulled from the glacier surface but we later estimated that it took around 60 to fill 12 of our 20 gallon sample containers. Loaded each container weighs around 90 lbs, getting them back on the helicopter for the flight out was no easy chore!

The dependence on helicopter flights and large sample volumes meant that we had very little time for exploration. This was too bad as the view from WP is truly spectacular. Our site was located next to the Bay of Sails, so named because large icebergs calving from the Ross Ice Shelf on the other side of Ross Island are frequently trapped in an eddy and driven aground in the bay. It looks like someone anchored a fleet of icebergs here, and the more distant ones really do look like sails. It isn’t difficult to imagine the frustrations of early explorers anxiously awaiting the arrival of a relief ship and trying to convince themselves of what was and wasn’t an iceberg.

Fortunately we will be visiting WP one more time, to collect fresh snow drifted near the edge of the glacier. In the meantime we’ll be working hard to get caught up on labwork. We have a flight to Taylor Glacier on Friday and over a thousand pounds of ice to melt and filter before then!