Korita Humphries

2010 JISAO Research Internship

The effect of atmospheric chemistry on climate change

Korita HumphriesThis summer I have had the intense pleasure of being a JISAO intern at the University of Washington in the Department of Atmospheric Sciences. In the eight grade, I developed a fascination for catastrophic events, and since then, I have grown up loving atmospheric science. Therefore, it was only expected that I would pursue this passion in my college career. I am a rising junior at Claflin University with a science and math background. Though I have been studying my major interests of catastrophic events and climatology on my own, this is my first opportunity to have any hands-on experience that will make a major impact.

I was placed under the mentorship of Becky Alexander and one of her graduate students, Eric Sofen. Her major research interests are understanding atmospheric chemistry and how it affects climate change. She works with the oxygen isotopes of sulfate and nitrate in snow pit samples, ice cores, aerosols, and water to determine various aspects of the past atmosphere. One of these aspects is determining the past oxidation capacity of the atmosphere, which controls atmospheric chemistry, and is usually defined by global mean OH concentrations. That is where the oxygen isotopes of sulfate and nitrate come in, as they provide a proxy to these past concentrations. This research breaks down into various facets, only one of which I played a part in.

My research focus this summer was improving the method for the analysis of the oxygen isotopic composition (D17O) of sulfate from small (< 1 mmol) samples, and then applying this method to snow pit samples from Summit, Greenland. The method involved converting three sulfate isotopic standards (dubbed Alpha, Beta, and Epsilon) of sodium sulfate (Na2SO4) into the silver form of silver sulfate (Ag2SO4) using the automated method of an Ion Chromatograph system, a cation exchange membrane, and a fraction collector, and the manual method of a cation exchange resin. Once the sulfate was in silver form, the samples could be dried using a Korita working in labfreeze dryer and transferred into quartz capsules. These capsules were then placed into an Isotope Ratio Mass Spectrometer where they are pyrolized to O2 and SO2 at a temperature of 1100 degrees Celsius. The resulting O2 is measured for its oxygen isotopic composition (d17O, d18O). With my research, the record of sulfate D17O values from a Greenland ice core can be extended from around 1700 until the present day.

My experience during this internship was been phenomenal. The weekly meetings with my mentor’s research group and the ones with the other interns allowed me the opportunity to learn about other scientists’ efforts in this field and how they are likewise impacting the world with their research. I have bonded with the other interns and, together, we have claimed the city of Seattle, whether it was our canoeing trip or hiking up Mount Rainier. This internship is one I will never forget, with memories I will take back home with me to St. Louis, MO!


Research poster

Korita's research poster

Click poster for larger view [PDF]