Monday, January 12, 2009

Oxygen, pt.1

One of my main duties aboard seems to be taking shape. I'll be
responsible not only for sampling water from the rosette, but for
analyzing the dissolved oxygen (DO) content of the seawater we bring
up from below. There are actually two sensors on the CTD which can
read the DO content -- however, these need to be calibrated to values
which we determine through a titration on board.

Most people have heard about scientitsts in the Antarctic who study
ice cores and the gasses trapped in them -- when we study DO we are
doing roughly the same thing except there are things living in the
water and the water can move around faster than ice.

Three processes that we're interested in can change the dissolved
oxygen content of seawater -- equlibration with the atmosphere when
the ocean "touches" it at the surface, biological use as
phytoplankton/fish/etc are broken down by bacteria and/or other
creatures, and interaction with glacial ice. Can anyone come up with
reasons how these processes might affect the oxygen content? Given
that info, can you think of ways we can use it to study circulation
around Antarctica?

Barney's class was looking at dissolved of in a freshwater system.
I'm interested what sort of concentrations they got?. How and why
does oxygen in freshwater change? What would happen if you kept
putting salmon in the same water? Maybe we can compare what's
happening to their water with what's happening here...

Life is going well here but the workload has increased due to a lot
of tests on the titrator and on our sampling technique. Mexican
night last night; that's a highlight for me so far. Lots of
crabeater seals out on the ice but fewer penguins so far!

1 comment:

  1. Oh boy. I'm going to have to think about that interaction question. Thinking about my old salmonoid tanks and working on the Columbia tributaries, I remember the flux of O2 levels depended on rain, water movement (in the tributary, meaning rip-rap and pooling within the current) and sediment influx. When we had high run off from melt or rain, we really saw increased DO levels and as the movement decreased, we saw drops. Of course the biology was influencing with various blooms as well.

    So what type of penguins? Or can you tell?