Welcome to the web site for Sediment and Solute Transport on Rivers and Margins (SSTORM) Research Group! Reide Corbett and J.P. Walsh from East Carolina University and the UNC Coastal Studies Institute lead the team.
Check out our research in/on wetlands, estuaries, barrier islands, shelves and groundwater.

Friday, February 21, 2014

Science at Sea

We are about 48 hours into our 5 days of science on the Laurence M
Gould. Wait a minute, let me give some background…

Our science has two components: 1) a nearshore focus that is trying to
quantify the amount of melt water and groundwater discharging to the
coastal ocean; AND 2) an offshore component that is focused on
evaluating the cross-shelf mixing of the freshwater discharged near the
coast (linking the nearshore with the offshore). So, our group has
spent ~7 weeks working in the nearshore at Palmer Station. Our time on
the LMG is focused on the offshore component. Although I will spend
almost 5 weeks on the Gould, I am only working on my science for ~5
days. We have about 8 days of transit between Punta Arenas and the
Antarctic and the LMG also has at least two additional operations that
it is completing besides the research of our group (i. another science
group focused on collecting organic rich soils from several islands
along the peninsula; ii. Collecting environmental samples from East
Base, an historic land mark around 68 degrees south). So, we all are
essentially sharing our time on the Gould.

OK, so that sort of puts our cruise in a broader context, logistically.
Again, we are 2 days into our 5 day cruise. The first picture is a
Google earth image of our cruise track (red line)…it shows the ships
current location (the orange ship), Palmer Station (yellow star), and
stations where samples were collected (white circles). So, we have been
working in two fjords (Beascochea and Baralari) and are now headed north
to Flanders Bay (a 5 hour steam and a fjord we sampled last year). We
will then start sampling stations moving away from shore on the
continental shelf (see picture of one of our lab benches on the LMG).
That's the basic plan…

Well, the best laid plan… We have not been without some problems
and delays along the way. Our cruise is primarily dependent on a
single instrument (or a composite of instruments) called the rosette
(see picture of complete rosette). The rosette has two primary
components, a CTD package and a bank of 30 liter (~7 gallons) niskin
bottles. The CTD measures conductivity (a proxy for salinity or the
amount of salts dissolved in the water), temperature, with depth. This
package also includes sensors to measure dissolved oxygen, fluorescence
(a proxy for the number of primary producers, known broadly as
phytoplankton in the ocean), and transmissivity (or essentially how
clear the water appears). Niskin bottles are containers used to collect
water samples from whatever depth the operator decides. So, we can
lower the rosette through the water column, all the while seeing
realtime how this list of parameters changes with depth. Then, with the
push of a button, we can close a niskin bottle, collecting a sample at
that specific depth of interest.

Well, we have been having some serious problems with the rosette so far
this cruise. The main problem is the communication with the niskin
bottles…so we can't tell them when to close. That's a problem
when you want to collect water from depth. Of course the show must go
on and when you are at sea, you MUST be flexible and deal with the hand
you are dealt…it's not like we can simply run out to Radio Shack and
buy a new one. At this point, we have stripped the rosette down (it is
now a naked rosette…see picture). We still want to get the
information from the CTD, so we have removed all the niskin bottles. If
you don't and send them to depth while they are closed, the bottles
(made of thick plastic) will simply implode! So, the naked rosette goes
down and gives us some understanding of the water column structure, then
we sample surface waters with our own pump (1 meter depth) and from the
ships intake (6 meter depth; see picture of Jared filling tank with
water from ship's intake). It is allowing us to measure our tracers
shallow in the water column and still have some idea of what the whole
water column looks like. At this point, it is the best we can do!

So, that's the water sampling (simply put anyway)…beyond that, we
are also collecting sediments from the ocean floor at each site (see
picture of coring from aft A-frame). This will help us determine
whether the tracers we are using to track groundwater and meltwater also
have a benthic (ocean bottom) source. These sediment samples are simply
being collected and stored…the analysis will be done when we return to
our home institutions.

Hope that gives you some idea what we are doing and how we do it…feel
free to post any questions you might have.

Reide aka Chief Scientist

1 comment:

  1. Thanks for the lesson Reide, and good luck with the rosette. Ughhhhhhhh