Phyllosilicates galore

Today was a good example of the varied rhythm of research. Whereas yesterday was mostly packed with lab work, today I was based in the office, reading materials on different types of clay molecules in order to better understand the work we're doing in the lab. Our reading materials were from lecture supplements to Scott's soils course (Scott as in Scott Fendorf, the faculty member who runs our project and many others). I learned all about tetrahedral and octahedral oxygen-based clay structures... which sounded scary until Sarah brought out some models!

A simple model of a phyllosilicate comprised mainly of oxygen atoms (red).

A model of the muscovite we work with. One can see clearly on this image that there are two main "layers" connected by a sheet of potassium atoms (yellow, center). This space between the layers allows the phyllosilicate to physically expand in the presence of certain substances such as water or some ions.

The important thing to understand for our work from these structures is that these clays have a permanent negative charge. Many of the non-oxygen ions originally present in the structure are exchanged through long-term processes for ions with a lower charge, giving the once-neutral clays a negative charge. This greatly affects their behavior and has implications for our research on different ions' interactions with clay in water.

We also had the first of our weekly SESUR/SURGE/MUIR lunch seminars (between the three undergraduate research programs in the School of Earth Sciences). Today Assistant Professor Nicole Ardoin came to talk to us about her work studying environmental learning behaviors. It was a good way to take a break from the lab and meet the other students doing similar work on campus this summer.