No one knows the exact amount of plastics discharged into the ocean. Some studies report conservative estimates of up to five million tons, others as high as 13 million tons. This raises a problem for scientists. At the oceans’ surface, they only find a fraction of what has been released. So where is the rest?
This question is now being addressed by the research project HOTMIC (Horizontal and vertical oceanic distribution, transport, and impact of microplastics). The project, which will run over three years, is funded by six European countries under the framework of JPI Oceans, with a total budget of €2.3 million.
“Less than 10 per cent of the plastic entering the ocean can currently be detected”, explains project coordinator Dr. Mark Lenz from GEOMAR. The reasons for this are manifold. “Partly it is due to the fact that the plastic breaks down into tiny microplastic particles that we can only detect with difficulty at sea using current methods", adds marine chemist Prof. Dr. Eric Achterberg, one of the main applicants to the project. It is also still largely unclear which mechanisms control the transport of the plastic to the depth and what ecological effects such phenomenon might have.
The HOTMIC project aims to close these knowledge gaps. To do so, it focuses on the North Atlantic as a model region and investigates the pathways of plastic coming from the continent into the North Atlantic Ocean gyre. The project takes into account microplastics sized down to less than 10 micrometers, investigating which physical, chemical, but also biological processes play a role in plastic distribution. In addition, the participants aim to develop new analytical techniques that simplify the detection of microplastics and help to assess the risks of these pollutants for the marine environment.
Before the official start of the project on 1 April, the Kiel based research vessel ALKOR has already collected samples and data for HOTMIC along the European west coast. From 5 to 26 March 2020, ALKOR sailed along the West European coast and collected samples and data in the outflows of major rivers such as the Seine, Thames and Elbe, but also in the Strait of Gibraltar and off the Belgian North Sea coast. "This covers the first part of the transport route from the rivers into the coastal waters", explains Dr. Aaron Beck from GEOMAR, the scientific expedition leader. “The samples must now be examined in the home laboratories,” he adds.
However, this poses a challenge for the team in COVID-19 pandemic times. Many particularly sensitive samples should in fact be transported to the partners in Belgium, Denmark or Estonia immediately after arrival in Kiel.
“Fortunately, many colleagues at GEOMAR spontaneously provided us with appropriate storage facilities so that we can keep the samples here safely until the situation returns to normal,” says Dr. Beck.
The HOTMIC consortium consists of:
- GEOMAR Helmholtz Centre for Ocean Research Kiel
- Institute of Hydrochemistry (IWC), Technical University Munich (TUM)
- University of Southern Denmark (Denmark)
- Instituto Português do Mar e da Atmosfera IPMA (Portugal)
- MARE - Centre for Marine and Environmental Sciences (Portugal)
- University of Pisa (Italy)
- University of Ghent (Belgium)
- University of Tartu (Estonia)