2 August, 2002

We are on station on the East Barrow Canyon transect. A transect is the sampling line we follow in a given area. So far we have sampled on our way up along the Alaskan Coast, and we have completed one transect, Barrow Canyon. If you check the cruise course map on the main page of the website, you can see that, on the East Barrow transect, the stations are fairly close together. We finished our benthic sampling by midnight last night, moved to the next station, and began the first CTD cast at 1 AM. The stations are also shorter in general because we are only at 500 meters, and we will be moving to more shallow depths as we progress along the transect. Once we move onto the next transect line, we will go from shallow waters over the shelf to deeper waters on the slope again.

Today I spoke with Christine Pequignet and Paul Lethaby. Although Christine is from France and Paul is from Wales, they are both research technicians working at the Bermuda Biological Station for Research. You can check out the place where they work by going to www.bbsr.edu. Christine works with Nick Bates, co-Principal Investigator (PI) on this project, and Paul works on a program called BATS (Bermuda Atlantic Time Series). Since 1988, the BATS program has provided monthly data about the biological, physical, geological, and chemical features of the Atlantic Ocean water at one parcticular site off Bermuda. On this SBI cruise, Christine and Paul are sampling water to measure carbon in the water column (at different depths).

Each time the CTD service cast comes on board, Paul and Christine take two bottles of water from each of the twelve bottles on the CTD rosette. Each bottle is about one quarter of a liter (about the amount in a can of soda), and each one must be transported back to Bermuda for analysis. All totaled, Christine and Paul will bring home 1000 bottled samples from this summer cruise to add to the 800 bottles from the spring SBI cruise. Once they are back at the lab in Bermuda, someone else will process each bottle at a rate of ten bottles/day. Paul is smiling in the picture below (next to the boxes of bottles) because he is not the one who has to process all the samples. His job will be to compile all the data on the computer.

During one step of the carbon cycle, carbon dioxide (CO2) is exchanged between the atmosphere and the surface of the ocean where it is dissolved in the water to become dissolved inorganic carbon (DIC) or dissolved CO2. Once in the water, the CO2 can be used by phytoplankton which convert it into parcticulate organic carbon (POC) or it can remain dissolved in the water in organic (DOC) or inorganic (DIC) form. If the phytoplankton die and sink to the bottom they become a part of the sediments that Jackie is sampling. That’s one way that the ocean removes CO2 from the atmosphere. When you read in the newspaper that oceans can be a “sink” for CO2, they are referring to the removal of CO2 from the atmosphere. Sometimes the carbon from the dead phytoplankton stays in the sediments, and sometimes it dissolves and is released into the water again. The combination of the parcticulate organic carbon (POC) and the dissolved organic carbon (DOC) makes up the total organic carbon (TOC). Christine and Paul filter the water samples they take to determine POC. Do you remember Cindy Moore (see my journal for July 20)? Cindy is analyzing DOC, and her results will be combined with those from Paul and Christine to get TOC. So POC + DOC = TOC. Get it? It’s important to know what happens to the carbon in the Arctic Ocean so scientists can tell if the ocean is a sink (takes up carbon from the atmosphere) or a source (adds carbon to the atmosphere).

Christine and Paul also sample the water from each depth to measure the alkalinity of the water. That will help them to know how much of the CO2 is re-dissolved in the water. The data from the science service team is critical because the amount of CO2 that is re-dissolved depends on the chemistry (temperature, salinity, etc.) of the water. By knowing the amount that is re-dissolved, they can get an idea of how much has changed because of biological activity and how much carbon reaches the bottom.

Paul and Christine are measuring carbon in the water column. Others on board measure the carbon in the sediments, sample the plankton that use the carbon, track the amount of light that reaches into the water for the phytoplankton to use the carbon, analyze the water for various chemical and physical factors, or trace the water itself. All the projects on this SBI cruise are tied together in an interdisciplinary effort to understand the way carbon cycles through the western Arctic Ocean.

Christine Pequignet is taking water from the CTD cast in order to sample for alkalinity and dissolved CO2 (also called dissolved inorganic carbon or DIC).

Paul Lethaby helps Christine collect water from each service cast. They will have 1000 bottles to take home from this cruise to add to the 800 collected on the spring SBI cruise.

These are just a few of the boxes of bottles which will be shipped back to the Bermuda Biological Station for analysis. Paul is smiling because he doesn't have to do the analysis. His job will be to compile all the data on the computer.

This is the filtration set up that Paul and Christine use to separate the parcticles from the water they sample.

This is the drying oven where each filter must be dried and stored in yet another bottle to be brought back for analysis. At least these bottles are smaller!