Penguins & Particles
This morning, it’s all penguins all the time. Now that we’re nearing the end of the sea ice, wider cracks and small patches of open water ease the ship’s passage. It’s a perfect habitat for the small Adélie penguins, providing safe places to rest away from predators and for entry into the water to feed. They speed-waddle and slip (or often trip) onto their bellies and “swim” along the ice, calling raucously to each other all the while. The Weddell seals seem less abundant here, but we still see the occasional one sleeping on the ice.
Today, I visit with Pat in the aft dry lab, who explains a bit more about the processes he’ll use to pump, collect, and store particles from the seawater for later analysis back in the URI-GSO lab. Seawater will pass through two screens, each with different sized mesh, to catch both larger and smaller particles.
This matter is called “marine snow”—and it’s a constant rain of material down through the water column. As it descends, marine snow provides a rich feast for those who live in deeper waters. Some particles are captured by upwelling waters and return to the surface, where they might be consumed by the organisms living there. Diatoms, those microscopic plants we have come to study, use some of the nutrients provided by the decay of this organic matter. At each station, we will take samples of marine snow from a number of depths in the ocean and eventually determine what is in it.
I ask what kind of particles they expect to find.
“We'll be getting all kinds of stuff, really,” says Pat. “We ought to get diatom chains and large individual diatoms. We'll also get aggregates and pieces of zooplankton, fecal pellets, too—basically any bits and pieces that make it onto the two screens. We won’t know for sure until we take a look at them!”
Jessica has heated the combustion oven to 500 Celsius (about 930 Fahrenheit). Inside it are glass fiber filters, which will be fired for 5 hours to ensure any organic matter is burned off and the filters are sterilized. They will use these to store the particles they retrieve through the pumping process for analysis when we return to the States.
We watch the marine technicians setting up the piston corer, the piece of equipment the other scientific team from Lamont Doherty Earth Observatory will use to take samples of sediment (mud) from deep into the sea floor. These will hopefully will provide records that date back 30-150 thousand years. In contrast, our team will use a piece of equipment called a megacorer to take shallower samples of the marine snow that has reached the sea floor and accumulated as a thick oozy mud. When we return to the USA, we will have samples of living diatoms from the surface waters where they live, dead diatoms and other particles that are sinking as marine snow, and diatom skeletons hundreds to thousands of years old.
As they set up the piston corer, the marine technicians wear their flotation jackets and hardhats. They are hooked to lines attached to the ship to keep them from falling into the frigid water.
Becky and Pat work on the IC—an essential machine for measuring the amount of nitrate in sea water.
By mid-morning, we have left the sea ice behind. We’re still about two days from our first sampling station in the area long-known by sailors as the Screaming (or Shrieking) Sixties for its frequently ferocious seas and weather, but for now it is smooth, gentle sailing—perfect as we get our sea legs.