The first analyzes are ready
All the way around the world, Statsraad Lehmkuhl collects data, both on the weather, and on the conditions of the sea below the ship.
One of the instruments on board takes continuous water samples, completely automatically. Students Erlend Mundal and Erik Furevik monitor the system, and make sure it works properly.
Sampling is stopped when the ship is close to port.
- This is to prevent clay, sand and other micro-rubbish from entering the system, says Erlend Mundal.
The CO2 content of the seawater
All data collected is shared with researchers on land, and now the first analyzes are getting ready.
The map below was mailed to the students this weekend.
Meike Becker is a scientist at the Department of Geophysics at UiB, studying the CO2 content in seawater.
- The ocean absorbs a lot of CO2, about 25 percent of what is released into the atmosphere, she writes in an email to Erlend and Erik.
- Of the rest, 30 percent is taken up by the vegetation on land, the rest stays in the atmosphere.
So, knowledge about the ocean is important for the researchers trying to understand the mechanisms behind climate change.
Water dissolves CO2 by forming carbonic acid. The formula looks like this:
H2O + CO2 = H2CO3
Not all CO2 is converted to carbonic acid, some "floats around" in the water as CO2 molecules. It is the amount of these molecules Erlend and Erik measure; pCO2.
- The temperature and pressure determine how much is dissolved, Becker explains. But in general, cold water manages to dissolve more CO2 than warmer water.
This is one of the reasons the ocean does not absorb the same amount of CO2 everywhere. The area near the poles, as in the North Atlantic, absorbs a lot, while the sea near the equator often emits more CO2 than it absorbs.
Since temperature is a factor it is not surprising that pCO2 varies throughout the year. pCO2 is highest during the winter, decreases through spring when the amount of phytoplankton increases, and is lowest in summer.
On the way south
The map Meike has sent plots pCO2 measured on the way south to Cadiz.
- Sailing into the shallow areas in the southern part of the North Sea, concentration is rising. This is both because the water is warmer here, and because the phytoplankton her has used up all the nutrients, and dies. When the plankton then is broken down by bacteria, nutrients and carbon are released. Then the amount of CO2 that is dissolved in the ocean and thus also pCO2 increases, Meike explains.
The further south the ship sails, the warmer the sea gets, and the more pCO2 is expected to increase.
The sampling did not start until the ship was west of Denmark, it took a while to get the equipment up and running. As you can see, the map also lacks the last stretch towards Cadiz.
- Meike follows the measurements from land, and at a point she realized that there was a small gas leak, Erlend says.
Erlend and Erik asked the chief engineer for advice. He sprayed soapy water on the pipes in the instruments to see where gas was bubbling out, and fixed the problem by tightening the leaking coupling.