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A scientific expedition led by the Catalan Water Research Institute (ICRA) studies the destruction of the carbon sink in the sediments of the Aral Sea (Kazakhstan), the largest dried lake on the planet that has disappeared by 90% and considered one of the most serious environmental disasters of the 20th century.
Lakes store large amounts of organic carbon in their sediments, which provide a fundamental ecosystem service for society: preventing the emission of CO 2 into the atmosphere. However, when the lakes dry up, the sediments come into contact with atmospheric oxygen, increasing the activity of the microorganisms that degrade the organic matter. This causes the organic carbon trapped in the sediments to be released in the form of CO 2 , destroying this carbon sink or reservoir and contributing to climate change.
The aim of the project called Alter-C, which is funded by the Agencia Estatal de Investigación , is to understand how the carbon deposits found in lake sediments are released when they dry up. To do this, the team led by the ICRA , and integrated by members of the Laboratoire des Sciences du Climat et l’Environnement of the French CNRS , the University of Malaga and the University of Aarhus (Denmark) , apply the most innovative methodologies for the measurement of gas emissions and carbon stocks.
Rafael Marcé , researcher in the Resources and Ecosystems Area of the ICRA , explains that ” knowing how the carbon sink of the Aral Sea is being released into the atmosphere will allow us to estimate what the effect of this process on atmospheric CO 2 concentrations on a global scale, and it can become a very powerful argument to recover what used to be the fourth largest lake on the planet .”
The expedition to the Aral Sea of the Alter-C project takes place for 20 days, from August 26 to September 15, and ” constitutes a first-level scientific milestone, as it is the first study of this nature that is carried out all over the world ” – adds Marcé .
The research team moves to Kazakhstan and, with the logistical help of the NGO Aral Tenizi , dedicated to the recovery and protection of the Aral Sea, travels along the former lake bed, now dry and turned into a desert inhospitable the size of Ireland, to collect evidence of the release of the carbon sink. This will take them on a journey of hundreds of kilometers from the old shore of the lake that began to dry up in the 1970s, to the center of the lake, which has dried up in the last decade. During the journey, the researchers collect evidence of sediments to measure the carbon released and will measure emissions of CO 2 and methane from the surface of the new desert.
The people participating in the expedition are Rafael Marcé (ICRA), Núria Catalán (CNRS), Enrique Moreno and Sofía Rodríguez (University of Malaga), Zhanna Tairova (University of Aarhus) and Makhambet Mukhtar (Aral Tenizi).
The group is also joined by the audiovisual documentary filmmaker and biologist Laura Carrau , who has previously carried out several scientific campaigns and is in charge of recording graphic and audiovisual material. Thus, on the one hand, during the expedition, material can be provided to the media that request it and, subsequently, a documentary will be made about the scientific team’s research in the Aral Sea.
