GEOMAR study investigates the impact of sediment resuspension induced by trawling and other natural processes in Kiel Bight.
GEOMAR study investigates the impact of sediment resuspension induced by trawling and other natural processes in Kiel Bight.
When bottom trawls are dragged across the seafloor, they stir up sediments. This not only releases previously stored organic carbon, but also intensifies the oxidation of pyrite, a mineral present in marine sediments, leading to additional emissions of carbon dioxide (CO2). These are the findings of a new study conducted by the GEOMAR Helmholtz Centre for Ocean Research Kiel. Based on sediment samples from Kiel Bight, the researchers investigated the geochemical consequences of sediment resuspension. Their conclusion: areas with fine-grained sediments, which play a crucial role in CO2 storage in the Baltic Sea, should urgently be placed under protection. The study has now been published in the journal Communications Earth & Environment.
The resuspension of seafloor sediments – triggered by human activities such as bottom trawling as well as natural processes like storms and tides – can significantly increase the release of carbon dioxide (CO2) into the atmosphere. When these sediments are exposed to oxygen-rich seawater, large-scale oxidation of pyrite occurs. This reaction plays a much greater role in CO2 emissions than previously assumed, exceeding the contribution from the oxidation of organic carbon. The new study provides the first quantitative evidence of this effect in the western Baltic Sea.
“Fine-grained, muddy sediments are important reservoirs of organic carbon and pyrite,” says lead author Habeeb Thanveer Kalapurakkal, a PhD student in the Benthic Biogeochemistry working group at GEOMAR. “We already knew that sediment resuspension can release significant amounts of CO2 into the water column. But until now, it was believed that this was mainly due to organic carbon oxidation.” The new study now shows that the major part of the CO2 release is caused by pyrite oxidation.
Read more at Helmholtz Centre for Ocean Research Kiel (GEOMAR)
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