Tom's Blog

Blog Post #1

For the last two weeks I have been working with Sverre, a graduate student, on her project in the General Program. Over the last two years, Sverre has been working in Patagonia, collecting lake bed core samples from isolated and pristine waters to determine how the westward winds, circling Antarctica, have changed over the last 10,000 years.

During my first week Sverre worked on teaching me relationships between wind, weather, isotopes in the lake water and so on. To do this I read parts of a scientific paper called "Paleoclimate interpretation of stable isotope data from lake sediment archives". After each night of reading Sverre and I discussed what I had read. Here is (some of) what I learned (to list everything would take a while):

Through studying silicates and carbonates in sediment, the ratio of oxygen 16 and oxygen 18 isotopes can be compared over the years. There are many things that the change in the ratio can inform a scientist of. In evaporation, heavier isotopes tend to evaporate last, so a year without much weather could result in a larger percent composition of oxygen 18. Additionally, the change in isotope composition can inform of how the temperature changed. As temperature increases the percent composition of oxygen 18 decreases. The percent composition of these isotopes can also be affected by the catchment, precipitation, and any vital affects. Overall, there are many things for Sverre and I to look for, and I am excited to learn how to handle so many factors while trying to find a conclusion.

Blog Post #2

For the last two weeks Sverre and I have moved on from talking about the science and detail of the works of the project to preparing samples to analyze for her project. For the first week after my first blog post I started off by dissecting sediment core samples.

First we would fetch the cores that we were about to bag that day from the refrigerator. Then, after descending into a basement lab of the Mitchell Building, we would mark each centimeter of sediment, making extra marks on every ten centimeters. Once this was done we labeled 150 or so bags with GAM 14 -18 - 1, 2, 3 or 4 (I will never forget this phrase! (: ) and the centimeter number. (GAM stands for Gulfo Admiralante Monte, the fjord location, 14 means that the core was done in 2014, 18 is the location site, and the last number is the core section. Also something that may be of interest is that the core comes in one and a half meter sections, with the bottom core labeled as 1 because it is the oldest section, however, the centimeter at the top of each section is considered the first centimeter so that cores can be compared more easily.) Anyways, after all the bags have been labeled, we would uncover the core and cut centimeter slices of mud from the center of the core (to avoid smear overlap from other centimeters) and put them in the bags. I am proud to say that I am now a professional mud slicer, now that I have done this process for about 5 meters of core. Finally we would separate sample bags with more bags and put everything back in the fridge, finishing about one core per day.

For the next couple of days Sverre and I worked on learning how to write a good abstract. After reading several papers and trying to write one myself, I felt fairly confident with the task. Finally, the last thing that we have done up to now is try to sieve some samples to see how Sverrre's bulk samples compare to analysis of purely authigenic samples (if there was a change in offset between the bulk and authigenic, it would mean that the biogenic data would also have to be considered in her work). Fortunately, but sadly, there were not very many signs of biogenic life in Sverre's core. This means that she doesn't have to take into account the change in oxygen isotopes in ostracods with temperature (authigenic material does not change with temperature) from skewing her bulk samples.

Now you are up to date. I hope you enjoyed my blog!