Adventures in Isotopes

By Jane Hamel, Middlebury College

This year, my research group is planning to take snow samples from the same snowpit multiple times. We want to study how the snow changes over time as we experience different weather patterns such as rain and sunshine.  We are hoping that this will help us answer our big picture question for the summer: what affects the ratios of water isotopes on the Juneau Icefield.  

Now to explain a bit about isotopes and how we can use them in our project this summer!  Not all water molecules are the same.  Most are the same weight, but there are some that can be heavier.  By comparing the ratio of heavier to lighter water molecules in the snow, we can learn about the snow and the conditions in which it formed and fell.  We will give a more thorough explanation of isotopes in a later blog post.

We were excited to start this project and kick off our summer research.  We planned the pit location to be adjacent to our ski hill for easy access, as we would be coming back multiple times to hopefully get new samples.  The process of probing and digging went well; we had an idea that the pit would end up being about 160 cm deep.  After some digging and snacking we were more than halfway through our pit, at about 100 cm when the snow started getting slushy.  Confused, we dug a bit deeper and wider to see if the slush layer continued throughout the snowpit.  Not only was the slush layer continuous, but it was 60 cm deep in some places, continuing all the way to the bottom of the pit. After shoveling out some of the slush, we saw that digging further would not be possible; the slush turned to water after a few centimeters, and even if we could somehow remove all of the water, it would just fill in again.  We were all surprised to find out that glaciers can have water layers in them, and we definitely could not have predicted it or known that our location had this.  

Alex Ihle floats on his therm-a-rest in the pool while recording data in the group field notebook.  JJ Graham takes a snow sample form the pit while Jane Hamel labels sample bottles and Chelly Johnson organizes the samples. Photo credit: Jay Ach.

Alex Ihle floats on his therm-a-rest in the pool while recording data in the group field notebook.  JJ Graham takes a snow sample form the pit while Jane Hamel labels sample bottles and Chelly Johnson organizes the samples. Photo credit: Jay Ach.

We decided to have some fun with our discovery, converting half of the pit into a pool by clearing out the rest of the snow and slush layer.  Some brave JIRPers went in for the inaugural dip, hot after shoveling in the sun.  On the other side of the pit we prepared the wall for sampling by making it smooth all the way down.  After collecting snow samples from the wall, we decided to also take one from the water in the bottom of the pit to add to our data of the pit.  

Even though the pit didn’t turn out how we had expected, it was still a really interesting discovery that we could learn from and use in our project. We were still able to collect data for our project, just with a bit of tweaking.  Since the construction of the pit, we’ve had two rain storms and after each one we’ve been able to go back and take new samples.  We don’t know yet how the water layer is affecting the pit and our data, but we’re excited to get our results at the end of the summer.  This project taught us that field work often doesn’t go as planned, but that you can make do with what you have and still get good data.