Leena's Blog

First Blog

I joined the Stanford Earth Sciences High School Internship Program (the general program) this past week. I am working with two doctoral students and three other interns in Professor Dunbar’s geochemistry lab. My supervisor Neil studies different layers of coral cores from the South Pacific to analyze ocean acidity levels and climate conditions over time. I am primarily working with Sverre, a doctoral student who studies lake sediment cores from Patagonia. She is analyzing the carbon, nitrogen, and oxygen levels from different layers of cores to see how the precipitation and wind patterns have changed over the past.

At the start of my internship, I learned about lab and chemical safety and took two online courses. Neil and Sverre gave me the big picture of their research and a tour of the equipment in the lab. I am also reading an interesting book called the Two-Mile Time Machine, which discusses the study of paleoclimatology using ice cores.

My work in the lab this week included crushing and weighing sediment samples for analysis. One of the things I learned in my first week in this internship was the importance of careful methods and precise measurements in sample preparation. When weighing out samples, I had to keep within a specific range of micrograms in order for the data measured to be valid. I also learned that careful labeling and lab records are necessary to manage large research projects. I found that research requires a lot of repetitive work, as I crushed over a hundred sediment samples using the same process. Sverre showed me her data spreadsheets and explained some of her findings. I helped enter some data.

I enjoyed getting together with all the other interns for lunch this past Wednesday. Everyone shared experiences. It was interesting to hear about what others are doing, both in the general program and the History of Life Program. We rotated among tables to meet more people. Lunch was followed by a Geospatial Tools workshop during which we used Google Earth to simulate the drowning of San Francisco as sea levels rise. I am looking forward to these Wednesday lunches in which I am going to learn more about the experiences of other interns and about other earth sciences research topics.

Second Blog

These past three weeks of my internship have gone by really fast - with labwork, paper discussions, intern meetings, a field trip, and the occasional extended lunch break with my lab group to watch world cup games! The most memorable event of the past weeks was a field trip for the general Earth Science program interns. Our trip included pinpointing our location at Windy Hill using a compass and triangulation methods, sketching rock layers at San Gregorio beach, examining rocks at Pigeon point, and seeing fossils at Ano Nuevo beach.

In our lab, we interns (Sam, Max, Emma, and I) took turns to nominate and discuss scientific papers dealing with different areas of Earth Science. We have read papers discussing the topics of paleoclimate reconstructions with isotopes, the Southern Westerly Winds, and climate variability. These discussions run by Sverre (the graduate student) have been interesting and enjoyable, and they have broadened my view of the field of Earth Sciences.

The paper I enjoyed the most was about the use of stable isotopes to reconstruct paleoclimates (“Palaeoclimate interpretation of stable isotope data from lake sediment archives” by Leng and Marshall.) It directly links to work I am doing in the lab. As mentioned in my last blog post, I am assisting Sverre, who is analyzing lake sediment cores from Patagonia. She measures isotopes of carbon, nitrogen, and oxygen to reconstruct the climate and wind patterns of Patagonia over the past 10,000 years. Sverre primarily runs her sediment samples on three machines in the lab to see their isotope contents – the 252 machine, the Coulometer, and the Delta machine. I help prepare sediment samples for these machines, and have also been able to run the Coulometer. The paper we read helped me to understand that scientists use the isotopic ratio of oxygen-18 to oxygen-16 in samples to see the amount of precipitation and evaporation that occurred in an area. Oxygen-18 is a heavier isotope than oxygen-16. Therefore, O16 evaporates before O18 does during dry periods. If the climate at a certain time was dry, then the sediment cores have a higher O18 to O16 ratio. If the climate was wet, then the ratio difference will be smaller. The 252 machine measures the ratio of Oxygen-16 to Oxygen-18 in the samples. The 252 machine also occasionally behaves erratically and drops vials, to Sverre’s despair! I learned that the Coulometer measures carbon content in samples and the Delta also measures carbon and nitrogen content. The carbon-13 content indicates a rise in lake productivity. Since productivity usually increases due to factors such as sunlight and temperatures favorable to life, carbon-13 usually covaries with oxygen-18 content in lakes, since the oxygen-18 is left behind in evaporation in higher temperatures with more sunlight. I learned that the carbon to nitrogen ratio can tell scientists where the organic matter in their samples originated from – aquatic sources (from within the lake) or terrestrial sources (deposited in the lake through precipitation).

We also read two papers from Science titled “Shifting Westerlies” and “Uncorking the Southern Ocean’s Vintage CO2.” These discussed the phenomenon of the southern westerly winds which circle Antarctica. I learned that paleoclimate evidence suggests that at the end of the last ice age 17,000 years ago, the westerly winds shifted south. When they shifted, it is believed that they caused upwelling of the Southern Ocean, causing CO2 rich water to move from the deep ocean up to the surface. Scientists are currently debating what factors caused the Westerlies to shift south 17,000 years ago and what effects that shift caused. Their findings are extremely relevant to today’s world, since the westerly winds are currently shifting south towards Antarctica!

Our group discussed two papers about climate variability’s effect on oceanic ecosystems (“Effects of interdecadal climate variability on the oceanic ecosystems of the NE Pacific” by Francis and Hare) and the Pacific Decadal Oscillation (“The Pacific Decadal Oscillation” by Mantua and Hare. I learned about a phenomenon known as the Pacific Decadal Oscillation (PDO) that is a pattern of climate variability that changes every 20-30 years. The PDO changes in sea surface pressure and sea-water temperature directly impact marine organisms, with some thriving and some nearly dying out (an example is that of Alaskan salmon and Pacific salmon). Scientists have not completely formed a model of PDO, and this effort is crucial, due to the immense scope of the PDO’s influence on the world’s climate.

In addition to receiving a broad education about topics in the field of Earth Science, working with graduate students in a research lab has allowed me to experience what their life is like. I learned how their research is a part of a larger community of scientific work. I have seen that contributing to scientific knowledge includes a lot of routine work – getting data points on a graph of hundreds includes multiple routine tasks. I also learned that food, particularly free food, is an important part of a grad student’s life. Every other Friday, we interns walked with Sverre to the Y2E2 building for free bagels and fruit! That small room was packed with people from the Earth Science department.

Last Friday, I attended a doctoral dissertation defense in the School of Earth Sciences. The thesis was about arsenic contamination in Asia’s groundwater. This was an interesting experience. The public defense seemed to be a celebration of the student’s completion of his doctorate degree – his friends and family members also attended. After the public defense was over, we left, and his committee stayed for a few more hours. This exposure made me realize the high level of effort a PhD requires – 6 years for this student. I feel that if I become passionate about a topic, pursuing a PhD would definitely be worth the commitment.

Third Blog

The weeks of this summer internship have gone by quickly. I have learned a lot during this amazing experience, and this last blog post is a reflection on my time in the Stanford Earth Sciences High School Internship Program.

I experienced what it was like to work in a science lab as a researcher. I saw how all the tasks that I performed – cutting, grinding, and weighing sediment samples from lake sediment cores from Patagonia, contributed to the data for the study of paleoclimates that Sverre was conducting. Though precise, repetitive laboratory tasks may be tedious, I better appreciate how essential they are to conducting credible scientific research. From weekly intern meetings and from my lab group’s discussions of scientific journal papers, I developed a broad exposure to the problems being researched in the field of Earth Sciences. I understand how global scientific problems are solved through an international community of scientists and researchers from different fields who are constantly disproving and proving each other’s theories. Through my interactions with my lab group, I found that the life of a graduate student is challenging, satisfying, and fun, and often centered around free food.

In this last week, we interns presented our summer experiences to each other. On Tuesday we visited the Stanford farm, the summer interns there showed us around, and we all made pizza in a clay oven. On Wednesday, I enjoyed presenting my work together with the other general program interns and the History of Life interns.

As I completed my last two days of this internship, I realized how I had become a part of this small group of researchers. I will miss my research mentor, Sverre, Neil, and the other interns. I hope that I will be able to attend Sverre’s doctoral dissertation defense in the near future.

I leave with many thanks to Jenny, Sverre, Neil, and Elizabeth for this amazing learning experience.