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Research trip to the mouth of the Amazon River: on the trail of the ocean’s material cycle

Andrea Koschinsky, Professor of Geochemistry at Jacobs University, will travel to the estuary of the Amazon – as head of an interdisciplinary research project
Andrea Koschinsky, Professor of Geochemistry at Jacobs University, will travel to the estuary of the Amazon – as head of an interdisciplinary research project. Photo: private
 
December 22, 2017
 
It is by far the most abundant river in the world. One-fifth of the Earth’s entire freshwater supply flows from its mouth into the Atlantic pushing the ocean’s salt water several hundred kilometers out to sea. In April, Andrea Koschinsky, Professor of Geochemistry at Jacobs University, will travel to the estuary of the Amazon – as head of a recently approved, interdisciplinary research project on board the research ship, Meteor. 
 
The Amazon River is almost 7,000 km long and is not only tremendously abundant but it also transports large quantities of trace metals such as iron and copper and dissolved organic materials. It is these materials that interest the team comprising Andrea Koschinsky, Prof. Thorsten Dittmar from the University of Oldenburg and Prof. Martin Frank from GEOMAR - Helmholtz Centre for Ocean Research Kiel as well as the four Brazilian partner organizations.
 
“We want to gain a better understanding of the material cycle in the ocean,” says Andrea Koschinsky about the M 147 research trip’s aims. “We will only be able to reliably predict the human impact on this cycle if we succeed in this”. Trace elements such as carbon, nitrogen, and phosphorus play an important role in the ocean as they are essential elements for the formation of biomass. However, all life needs iron – even the smallest marine organism requires it. 
 
The Amazon River carries many elements into the sea, including iron. Part of the elements flocculate when the freshwater meets the saltwater and mixes, they drop down and settle on the bottom of the river mouth as sediment. However, another part remains in the water and forms part of the material cycle in the ocean. On their research trip, the scientists want to find out exactly how these processes work, their interdependencies, interactions, and quantities. Their focus is on the flow of iron as well as other important trace elements and organic molecules.
 
The scientists will take the first water samples from the river where the freshwater is the purest. The ship will then follow the course of the river via the brackish saltwater and freshwater water system until its keel reaches the pure seawater. Sediment samples will be taken from the seabed, from the river at a depth of up to 100 m and from the sea at a depth of up to 2,000 m. The findings will also be used to record and understand disruptions to natural geochemical and biological process in the marine environment caused by people. Humans are intervening in the fragile ecosystem of the Amazon and changing it significantly in particular by building dams, deforestation, and intensive agriculture. 
 
The joint project financed by the German Research Foundation (DFG) is part of the international GEOTRACES program. Its aim is to record the distribution of trace elements and isotopes in the ocean and to understand the processes that control this distribution. The data collected will, among other things, contribute to a better understanding of the effects of climate change on the oceans.
 
More information:
 
Questions will be answered by:
Prof. Dr. Andrea Koschinsky | Professor of Geosciences
a.koschinsky [at] jacobs-university.de | Tel: +49 421 200-3567
 
Aboard the research ship Meteor, the team will travel to the estuary of the Amazon
Aboard the research ship Meteor, the team will travel to the estuary of the Amazon. Photo: Martin Visbeck / GEOMAR