Station 4

We are now finished with our third station and are currently in a 10 hour transit to our next sampling location. Station 4 was a lot of fun for me because I got to start work on my undergraduate thesis project. I have been taking classes towards an honors degree and one of the last requirements is that I do my own research project. My project examines photodecomposition of methlymerucry in seawater, a portion of the mercury cycle that has been given little attention. While there are many experiments in freshwater systems, including a study done by Dr. Hammerschmidt and colleagues in Artic Alaska lakes, little has been done to understand the mechanism in seawater. My research models experiments of methlymercury photodecomposition in freshwater systems and applies them to seawater.

Before arriving at a station, I have to "order" water to use for my experiments. Because my project is studying photodecomposition, I need to make sure that I am getting seawater from the surface and the from the top 10 meters which receive the most sunlight. The water sampling Rossettes are programmed at each station to open and close at different locations, enabling us to collect water from various depths. Once I have my water, a majority is filtered and transferred into 500mL Teflon bottles. The bottles are then spike with known concentrations of methlymercury and stored in incubation chambers. The incubation chambers are clear plexiglass boxes that have a constant supply of fresh surface sea water being pumped in/drained out (I'll try to post pictures soon!). Light is able to penetrate both the incubation box and the Teflon bottle and this will be assured by using a device to measure photosynthetic active radiation or PAR inside and outside of the box.

I will be running four different experiments with variations in initial methlymercury concentration, filtered v. unfiltered seawater, different amounts of PAR, and different locations/sources of seawater. I will collect and freeze my samples at sea to bring back to Ohio for analysis at Wright State! It will be exciting to see how much methlymercury is broken down by the sun and to compare that process to what we have observed in freshwater.

-Katlin