22 May 2004 - Part 1

Joined: 23 Mar 2004 Posts: 87

May 22, 2004 Saturday
8:00 AM Alaska time

There are many projects being conducted during this SBI cruise. It can
be a bit overwhelming so I thought I would introduce you to one project
at a time. Ron Benner and Richard Daw from the University of South
Carolina are studying the dissolved material in the water. The
questions they are trying to answer related to the SBI project are:
“Does shelf material get transported into the Arctic Ocean basin?” and
“How much material is transported?”

Terrestrial (land-based) matter is transported down rivers to the ocean.
Some of the material is dissolved and some of it is particulate matter
in the water column. Each river drains from a specific area of land and
the composition of the material feeding into a river is fairly unique
giving each river its own signature. Therefore, it is possible to
analyze ocean water samples and identify where the water and terrestrial
matter originated.

Ron and Richard take water samples to test for DOC (dissolved organic
carbon), DON (dissolved organic nitrogen), amino acids and sugars in the
water. They also isolate a material found in terrestrial plants called
lignin. On the Healy, they use a process called Solid Phase Extraction
to take lignin out of the water. When they return to the University of
South Carolina, the samples will be broken down into smaller components
that are then separated and analyzed. Using the analysis, Ron and
Richard will be able to trace from which river the water originated.

Richard Daw standing in front of the Solid Phase Extraction Cartridge.

Of course, it is not as easy as it sounds. Sunlight and microbes in the
water remove and change the lignin complicating the identification
process. (Note - In the Arctic Ocean, sunlight probably is not a
dominant degrader because the ice acts like a barrier, reducing the
amount of solar radiation exposure). Ron and Richard are conducting
additional experiments to account for the degradation. In one
experiment they filter seawater through a filter with holes 1000 times
smaller than a millimeter. Then they put the filtered water in a dark
cold place for 16 weeks and allow the remaining bacteria to degrade the
material. In another experiment Ron and Richard add a fresh Alaskan
river sample to seawater and measure the degradation over time. A
comparison of the two degradations should give interesting results.

Ron Benner filtering water for bacteria degradation experiment.

To see photographs taken by Steve Roberts of UCAR/JOSS, click here.