Baltic Sea Contributes Carbon Dioxide to the Atmosphere
The Baltic Sea emits more carbon dioxide than it can bind. Scientists at the University of Gothenburg, Sweden, have investigated the carbon dioxide system of the surface water of the Baltic Sea, in order to increase understanding of how the concentration of carbon dioxide affects seas.
"The capacity of the Baltic Sea to absorb carbon dioxide without major changes to the acidity of the water has changed in recent centuries. In the Bay of Bothnia, the ability to resist change has fallen, while it has increased in the south-eastern parts of the Baltic Sea," says Karin Wesslander of the Department of Earth Sciences at the University of Gothenburg.
Carbon dioxide is an important component of photosynthesis and it is consumed by algae. Algal blooms during the spring and summer lower carbon dioxide level in the water which results in higher fraction of carbon dioxide in the atmosphere. This means that carbon dioxide sinks into the sea. When the plankton subsequently die, they are broken down and the carbon dioxide reappears in the water. The windy weather that occurs during the autumn and winter causes water mixing, and the carbon dioxide returns to the surface. The sea acts as a source of carbon dioxide during these seasons.
Large differences across the Baltic Sea
"The study is based on 15 years of measurements from the sea outside of Gotland, 1994-2009, and shows that there are large differences between seasons, between years and between regions. One of the factors that contribute to these differences is the magnitude of the algal bloom. The wind is another important factor."
The Baltic Sea receives a large contribution from the many rivers that flow into it. The composition of river water, thus, plays a major role. Karin Wesslander's results show that the ability of the Baltic Sea to absorb carbon dioxide without a concomitant increase in acidity is significantly higher in the south-eastern parts and around the Gulf of Finland than it is in the Bay of Bothnia. This is because the rivers flowing into the Gulf of Finland and from the coastlines of the Baltic states carry more limestone, since they flow through limestone-rich rocks.
Source: ScienceDaily
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