Featured Scientist: Rachel Thomas

Today on the blog, we have a guest post from Rachel Thomas, learn about her research objectives during this survey in the Gulf of Mexico!

Rachel takes the CTD down to 2500m in the Gulf of Mexico!

My name is Rachel Thomas and I’m a PhD student at Florida State University studying the marine nitrogen cycle with the Knapp Lab.

Filtering sea water

On this cruise, I am looking at the concentrations of nitrate, a nutrient required by primary producers, found in the upper 300 meters of the water column. Water samples are prepared using a colorimetric technique that will turn the water varying degrees of pink, depending on concentration, and analyzed at a certain wavelength. I am also collecting water samples from various depths ranging from a depth of 2500 meters and 3 meters below the surface. These samples will be taken back to FSU where we will look at the different nitrogen isotope signatures found in the water parcel.

Rachel examines nitrate concentrations

Think of an isotope signature as a fingerprint, where each source of nitrogen has its own unique fingerprint. By comparing the known signatures of each source to our water parcel, we will be able to determine where the nitrogen is coming from.

Collecting water from the CTD rosette 

It is important to understand where these nutrients are coming from to fuel primary producers in order to better understand how changes in nutrient sources will affect the GOM productivity.