Discharging over 200 000 m3 per second into the Atlantic Ocean, the Amazon River is the largest river worldwide. As such, the changes happening in the region – extensive droughts on the one hand and floods on the other – are important on a global scale. In addition, the sediment found in river basins represent a kind of detailed archive of the river’s history for those who know how to read them.

“By studying the sediment, you get a better idea of how the river system worked in the past – this is particularly important for the people living nearby, because if you know the underlying mechanisms of the system well, you have a better chance of predicting what will happen in the future, depending on changes induced by human activity or climate change, for instance,” says CLIM-AMAZON coordinator Franck Poitrasson of the French National Centre for Scientific Research (CNRS).

The CLIM-AMAZON project is the continuation of a long-standing research partnership between the French Institute of Research for the Development (IRD) – now spearheading CLIM-AMAZON – and the Geosciences Institute of the Federal University of Brasilia (UnB) in Brazil. The two have been collaborating in a joint laboratory for 20 years.

The EU funding has opened the door for researchers from other EU Member States as well as Associated Countries to join in, building on past research, but also developing new avenues.

Of sediment and aerosol

Six research teams from four EU countries seized the opportunity to take part. The University of Amsterdam, for instance studied fossils of pollen present in the sediment to reconstruct the paleoenvironments – or past environmental conditions – in the region. “Thanks to this pollen, they were able to enhance our understanding of the paleogeography of the Amazon River basin over the last 10 million years, determining where the river was coming from and whether we had rainforest as now or drier conditions,” says Poitrasson.

The team from the German Research Centre for Geosciences (GFZ) focused on cosmogenic isotopes in sediment. These are produced in the minerals exposed at the Earth’s surface when a high-energy cosmic ray hits the nucleus of an atom. This triggers a nuclear transformation, generating radioactive isotopes which are then buried by subsequent sedimentation. Based on these isotopes, scientists can establish erosion models, and the timing of sediment transport by the river.

Another research proposal came from Imperial College London. The UK team conducted various geochemical analyses of the aerosol – particles and droplets – above the Amazon basin. This allowed the researchers to determine where the aerosol components came from and what they are composed of, providing a clearer picture of atmospheric circulation above the river.

On to new horizons

Now, with the project close to completion and the fieldwork finished, the researchers and are in the process of writing papers and communicating their findings. At the same time, the consortium is preparing a project proposal for a new international research cooperation call – testament to the success of CLIM-AMAZON in promoting fruitful collaboration between partners.

“In addition, the Brazilians themselves wanted to create a kind of structure that would match the European one,” Poitrasson reports. “Brazil’s national institutes for science and technology are large projects that can last up to six years and receive funding of up to BRL 10 000 000. So, they made a proposal for a project similar to CLIM-AMAZON, involving more Brazilian institutions. If this is successful, it would be a great counterpart to our project.”