Lab Rat

Some of my (Colby) fans have asked me to recount a day in the life of a pre-doctoral graduate fellow at the Smithsonian Institution. I am working on my dissertation research which is aimed at understanding the social networks that may have existed among people living in the Kuril Islands in the Russian Far East some 800 to 3,000 years ago. By using obsidian artifacts and tracing them to their volcanic source, I hope to understand where the obsidian came from, the routes and extent that people moved through in the Kuril Islands, and how people might have participated in local as well as regional social networks to maintain reproductive success and access to subsistence resources.

However, unlocking these secrets of the past requires me to spend 8 hours a day in front of various instruments using elemental analysis methods to determine the geochemical make-up of each of my 1,300 obsidian flakes. The instrument pictured above is a laser-ablation inductively-coupled mass-spectrometer (LA-ICP-MS). Each obsidian flake is put into a chamber where a laser vaporizes a tiny amount of the flake, and this vapor is transported by argon gas into a plasma ion source at 8000 deg. C where ions are generated and separated and then collected according to their mass to charge ratio. Unknown specimens (elements) can then be identified and measured by this extremely sensitive instrument.

I have also used X-ray fluorescence (XRF) on a part of my artifact sample. XRF utilizes an X-ray source to excite electrons in the obsidian material, causing ionization of the component atoms that releases energy when the electrons move out of their shells. The energy (fluorescence) is measured by a detector and the instrument determines the elemental composition of the sample material (for the Mid-Z elements).

So on a typical day, I arrive at the lab about 8:30am and pick up where I left off in running my artifact samples through analysis. Sometimes this requires testing the instrument settings and making adjustments, and re-running samples that returned ambiguous or suspect results. After a break for lunch from about 12:30-1:00pm, its back in front of the instrument for another four hours or so until its time to pack up and catch the Smithsonian shuttle back downtown so I can take the DC Metro home.

The work can be slow-going and tedious, but at times there are interesting discoveries, and often frustrating technical glitches, to break up the day. This is Science with a capitol 'S'.