SEA-ICE OPS
Some criteria to consider for selecting a station:
a. Ice floe with enough size to have the trace metal (TM) clean operations distant from
ship and adequately separate TM from non-TM ops (generators and pumped water
discharge).
b. Wind, sea ice/ship drift, direction of the current (can we get the ship in the perfect
position for all involved?)
c. Estimate of the ice thickness from ice broken at the side of the ship
d. Melt pond(s) abundance
e. Lead or ice floe edge for sampling
f. Enough snow to meet sample volume requirements
1.
Choose a suitable piece of ice that meets all the requirements for PIs to achieve their
research goals.
We would like to be as far from the ship as the captain and crew are comfortable,
based on the atmospheric conditions (fog, snow, ice thickness etc), to avoid
contamination issues.
A safety meeting likely precedes each ice station (with the CG in the hangar). This is
(or was) their policy. All ice sampling gear was staged there in the past. We should
be able to provide them with feedback after a test station (if we do one) and really
have this roped for ice station 1.
Kadko note: the first station will likely also serve as the test station. I suggest that to
accomplish this we allow for as much time as needed to work out all the kinks at this
station—even if more than 10 hours (with a break in between) is needed. No reason
why we could not to stay at this site for as long as is needed. This way we won’t sacrifice
time for setting up a separate test site, we will accomplish the goals of a test site.. and
sample successfully at site #1.
2. Try and position the ship so we are not drifting over the water column we are
attempting to sample.
3. Through clear discussions with the safety diver and polar bear guard, point out the
pre-selected areas where we will want to sample. Presumably, the two CG personnel
will get onto the ice prior to any scientist and test the ice. We would like for them to
avoid stepping over the sampling areas we selected when choosing the ice floe.
4. Offload personnel and gear. From the time we select an ice floe to the start of
sampling (getting the brow down, all equipment and personnel on the ice) could be an
hour or sometimes more.
5. Establish a path to the sampling site and always use the same path to minimize our
footprint on the ice. (I say this because we have a defined area for collecting cores.
This will allow us to better understand heterogeneity i.e. whether we can characterize
a piece of ice in a defined area (1 m2) or do random cores that result in the same
variability in TM concentrations.)
6. From this point it is up to individual researchers to collect their samples.
A. TM group is self-contained. They have hired a technician from Hajo Eikens’ lab
who is experienced and is being trained to be TM clean. For snow, ice cores and
high-res water samples we will follow something close to this (in order):
a. Set up tent, drill water-sampling hole and cover the hole. We will come back to
this hole after all other sampling is done. This separates water collection from drilling
by a substantial amount of time (4-6 hours). We are building a TM clean auger
similar to our ice corer.
b. Collect snow from the sea ice surface.
c. Transport snow samples back to the freezer on the ship.
d. Determine the approximate ice thickness at our site.
e. Collect cores
f. Collect ice algae sample
g. Collect core(s) for nutrients and other parameters.
h. Transport cores to the freezer if possible.
i. Set up water sampling gear.
1.
Teflon tubing for water sample collection will be attached to Sonde cable and will
extend to just below the Sonde.
2.
Sonde external display will give us a live reading for all instrument parameters
including depth.
3.
Water from just below the ice will be collected for the community at the sea ice
interface. Sampling will be done inside a tent. Pumped samples will be filtered
through an Acropak and unfiltered samples will be collected and distributed to PIs
(per our proposal). Higher resolution sampling for our purposes will be based on the
Sonde profile. (All water pumped up through the hole will be pumped into a bucket
and discarded.)
j.
We were offered an EM ice-thickness measurement backpack to fully characterize
ice thickness at each ice floe. This basically entails walking over the ice in a grid
pattern and gives us a map of the ice thickness. I am not sure we will do this but in
any case this would be done at the end of our work if time permits.
The following will be performed between the TM sampling and the ship:
B. Melt Pond sampling (W. Landing)
a) sampled at melt pond edge.
C. 7Be sampling (D. Kadko and M. Stephens)
a) performed in a tent
b) pump driven by a gas-generator
c) APL personnel (D. Stewart) to drill sampling hole.
D. Ice Edge sampling (C. Measures)
a) pumping from lead or ice edge to ~ 10m. Likely this group will also sample through
the TM opening for comaparison.