Friday, July 19, 2013

Renee Renn : Weeks 2-5 : Field Work aboard the Oceanus

Greetings!  Yesterday I returned from a ten day cruise aboard the research vessel Oceanus.  I have had the amazing opportunity to experience first hand the fragile and laborious process of collecting data in the field.  I had the pleasure of sailing with twenty six other individuals, scientists and ship crew, and overall I had a positive experience learning the ways of conducting research on a ship.  Now I would like to take you on a journey of the incredible adventure.


Two days before we set sail, we were up bright and early loading all the supplies onto a flat bed truck at OSU.  We then made our way to Hatfield Research Center in Newport, OR to where the Oceanus is docked.  We spent the day loading our supplies onto the ship and setting up all of our equipment  in the various lab spaces we would be using throughout the next ten days.  There are three main lab areas that we utilize to proceed through the steps of processing samples.  Under the next section, I will go through the steps of this process in depth.


This image is of the apparatus used to collect sediment samples on the ocean floor.  It is called the muli-core collector.  It can collect eight samples with each deployment.  On this cruise we collected samples from a depth of 200m.  After waiting for several minutes while the crane is lowering the muli-core collector in the ocean, we hear the crane operator over the walkie state that they have reached the floor and that they are coming back up.  We all stand by for recovery of the apparatus.

Once the muli-core collector is back on deck, it is now time to inspect the the sediments retrieved and determine which ones will be kept for processing.  Although the apparatus can collect eight samples at a time, it is very rare that all eight will be worthy of keeping as useable data.  Sometimes not all eight core tube arms will activate.  This is the part that will swing down under the core to keep the sediments from spilling out on its journey back to the surface.  To get a better idea, here are a few images of the apparatus up close.  

After the careful inspection of each core, the best ones are then gently removed from the apparatus and carried in the cold van lab.  The lab is located on the main deck toward the back of the ship.  It is a special lab that is kept at 34 degrees.  To maintain the composition of the sediments it is imperative to keep them at cooler temperatures.  In the cold van, we work in a glove bag to separate the core into nine intervals starting at the top and working our way down through the layers of sediment.  A glove bag is able to seal off.  We are then able to run a line of nitrogen gas into the bag as to not expose our samples to oxygen at this point.  The samples are spooned into centrifuge tubes.  We take samples at nine intervals for each core.  The following are some images of the cold van.  In the first one we are setting up the table that we did all of our work at in the the van.

The next step in the process is to then take these tubes, and run them through the centrifuge.  We run each sample for 15 minutes at 10,000 rpm.  In this step we are essentially separating the sediment from the pore water.  Pore water, also known as interstitial water, is the water that is trapped in between the sediment particles as they settle to the ocean floor.  Fun fact... the centrifuge is suspended in a special table that allows it to swing back and forth because the ship is in constant motion and in order for the centrifuge to function properly is must always remain in a vertical position.  There are also lead weights that we place on top of the centrifuge to help it maintain this position throughout its cycle.   

As gently as we can on a rocking ship, the next step is to take the samples up to the lab that is located on the top floor.  The next step is also done in a glove bag filled with nitrogen gas.  We are extracting the pore water from each tube with a syringe and pushing the sample through a filter.  It is still important at this step to not expose the samples to oxygen.  The collection of pore water is kept organized by interval level.  When we return from sea, there are a series of lab experiments that will take place on these samples in the lab at OSU.  The experiments are done to take a closer look at the Rare Earth Elements (REE) which is also the lanthanide row on the periodic table.  REE's are important because their geochemical properties enable them to be powerful tracers of chemical process.     

Overall, I feel incredibly lucky to have been a part of this field work experience.  I learned a lot from my mentors, Jim and April about how to collect good data and also how to maintain a level of attention to details in an environment that is always working against you.  It is definitely an experience I would repeat.    

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