06 June 2004

Joined: 23 Mar 2004 Posts: 87

June 6, 2004 Sunday
10:30 PM Alaska time

We are in transit toward the East Barrow Line. During a break from my writing, I went to the Aft Conn. The Aft Conn is located on the same deck where I write my journal entries and is a good place to go when I need a break. There are windows and excellent views of the starboard (right) and stern (back) of the ship. The Healy can be steered from the Aft Conn so there is also a large amount of instrumentation and it is fun to watch the ship's cameras.

Stern view from Aft Conn.

Jeremy Mathis was also taking a break in the Aft Conn. Jeremy is a PhD student from the University of Miami-Rosensteil School of Marine and Atmospheric Science-Division of Marine Chemistry. He is working very closely with Christine Pequignet from the Bermuda Biological Station for Research during this SBI cruise. Jeremy and Christine work for co-Principle Investigators, Dr. Dennis Hansell and Dr. Nick Bates, respectively. Together, they are collecting samples for the major forms of carbon within the water column: dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and particulate organic material (POM).

Jointly, they are trying to determine how much of the carbon in the water column is organic and how much is inorganic, if there are seasonal changes between spring and summer, and how the general distribution changes between the continental shelves and deep ocean basins. They need many samples to provide high-resolution data to address their questions. Therefore, they both sample all CTD service casts and take water from all collected depths whenever possible, concentrating especially in the top 200 m of the water column.

Both Christine and Jeremy filter water and store the samples to be analyzed at their home laboratories. However, their treatment of the samples is very different. Christine collects four liters of water into large plastic bottles from each depth. She uses an elaborate GF/F filtering apparatus that allows her to filter 1-4 liters for many samples at the same time. After filtering, she dries the filters and discards the water. When she returns to Bermuda, the entire sample will be peeled from each filter and analyzed for particulate organic carbon.

Christine uses a filtering apparatus that allows her to filter many samples simultaneously.

In contrast, Jeremy needs only 60 ml of water and uses an inline GF/F that allows him to filter as he is collecting his sample from the CTD. Jeremy keeps the water and discards the filter. He stores his water samples in a 0 degree F freezer. When he returns to the University of Miami, 10 mls will be analyzed for dissolved organic carbon using the Shimadzu TOC-V system. The remainder will be stored for potential future analysis. This fall Jeremy is going to try to "catch an eddy" to look at the bulk transport of DOC/DIC/POC and determine how much carbon is being moved and locked away in the deep basin.

Jeremy is attaching an inline filter to a Niskin bottle.

In addition to collecting water for filtering, Christine also fills two, 250 ml bottles from each depth. She fixes each water sample with 100 microliters of mercuric chloride to stop all organic processes and stores the bottles at room temperature. Upon her return to Bermuda, the bottles will be analyzed for how much CO2is in the sample (the total amount of dissolved inorganic carbon) and how much of each carbonate form exists in the sample (the alkalinity concentrations).

Christine is packing 250 ml bottles to be shipped to Bermuda for analysis.

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