• We are using radium isotopes as tracers to study the movement of shelf water, which is believed to be a primary source of iron for the Southern Scotia Sea. We will also study thorium as a tracer of particle flux in the upper ocean.

  Isotopes – variants of a chemical element

  Radium, thorium – types of chemical elements

  Flux - flow

• In the austral summer of 2005-2006, we conducted a study in this area. Preliminary data show that the shelf water is rapidly transported offshore. Our data correspond with the high iron inventory that the Measures group (University of Hawaii) observed in 2004.

• We hope to better understand the movement of shelf water. Comparison between winter and summer data might help us understand dynamics of shelf water movements. Understanding these water movements will help us further identify the source of iron as a limited nutrient in the study area.
  

• Most importantly, this is our first cruise. As graduate students, we have been learning how oceanographers conduct research at sea. Learning about different projects from biological, physical, and chemical oceanographers and seeing them work together as a team are some of the best experiences.. We are really lucky to be part of this cruise on the Palmer, the gigantic floating science laboratory.

• Besides gaining scientific knowledge from our project, we will share and discuss results with other oceanographers. Our collaborative works might reveal some interesting facts about the Southern Ocean’s nature.

• The study area is in the southern Drake Passage region, specifically the eastern and the western sides of the Shackleton Transverse Ridge. This location is important since it is a mixing zone between the ACC (Antarctic Circumpolar Current) and the shelf water. These two distinct water masses influence distributions of chemical elements and phytoplankton community in the region.

• For the radium analysis:

  • First, we collect about 550 liters of water in barrels.
  • Next, we filter seawater through manganese oxide infused acrylic fibers. These fibers will extract all the radium from the sample.
  • Then, we use custom made radiation detectors to measure the activity of radium in fibers.
  • Later, we will use radium activity data to calculate the export flux of the shelf water and associated iron.
    

Radium is a chemical element, which has the symbol Ra and atomic number 88 (see the periodic table) Image by Daniel Mayer or GreatPatton and released under terms of the GNU FDL

For our thorium analysis:

• We collect 4 liter bottles of seawater.
• To this we will add a thorium tracer, certain acids and bases, potassium permanganate and manganese chloride.
• We filter the solutions and bring the samples back to Woods Hole for the processing and counting of the thorium isotope of interest.
  

Thorium is a chemical element in the periodic table that has the symbol Th and atomic number 90. As a naturally occurring, slightly radioactive metal, it has been considered as an alternative nuclear fuel to uranium. Link