Researchers from the University of Oldenburg in Germany have kicked off a novel project to identify sources and trajectories of plastic waste in the seas.
To simulate plastic, they are using wooden "drifters" of various thickness, which are being released into the North Sea off the German coast and its tributaries. Each block bears a message asking anyone who finds them to report this via its website.
According to researchers at the university, an estimated 10 percent of the 300 million tons of plastic produced worldwide each year ends up in the seas.
To find out more, DW spoke to two of the project's researchers: PhD students Rosanna Schöneich-Argent, in charge of coordinating the drifters, and Florian Hahner, who is working on modeling with the project.
DW: Please could you tell me more about how the project works?
Rosanna Schöneich-Argent: It's essentially a wooden message in a bottle. People who find [the blocks] can report where they found them and the date. Each drifter has an individual number, and we then link the reports to the number identifying which was found.
If they don't get reported, they become soaked, sink down into the water, and microorganisms can eat them up.
If we find several at one location that may mean currents and prevailing wind directions are pushing them there - so litter might of course be there, too. We can go and see if there's an accumulation of rubbish, and that helps us find out the potential pollution source.
So we can backtrack to potential sources. We can then go to them and say, "Look guys, we have to do something about that litter, let's try and find a solution." We try to find strategies to deal with the waste - so our ultimate goal is that no plastic debris end up any more in the seas.
At the end of the day, we will have a more holistic idea - so if people do a beach cleanup, they can tell where the waste probably came from. Or we can find a potential polluter, and know where plastic enters the environment.
Florian Hahner: It's not that we want to find some bad guys. Many factories are interested in helping us, and most of the plastic manufacturers are also interested in solving the problem.
It's not that plastic is always bad - it's important to tell people: You can use plastic, but don't throw everything away, use it again.
How long does the project run for?
R.S.-A.: We will be checking out rivers and seas until 2018. We released 800 drifters in the North Sea last week from a vessel near Heligoland [a German archipelago].
We are releasing from a total of 14 locations [this year and next], some of which will also be in major German river systems including the Elbe. Over the course of the project, we will release 100,000 drifters.
We don't really know where they are going to end up. The models created over the last couple of years only modeled water and ocean currents - but we know plastics often stick up out of the water, where wind plays a role in pushing it further.
What are the biggest sources of plastic waste in seas?
F.H.: Microplastics are a big problem. Rubber from car tires is a big source of plastic waste - rubber dust is blown over the seas.
Plastic bags are a particularly big problem in the Baltic Sea and also in the Mediterranean. Plastic bags get eaten by animals, because they think they are jellyfish.
What are the dangers of plastic waste in waters?
R.S.-A.: There are estimations that a plastic bottle would last 450 years in water. Its impact on humans is still being researched. We know that when marine life eat plastic, they get internal blockages, and can die of starvation even though their stomachs are full.
When it gets to smaller particles, it can pass through the gut - but the chemical side is much more complex, there are all these additives we don't know about. The plastics industry only gives out information on about a thousand of the additives that are used to make plastic more stable, but that's only a fraction.
The smaller these particles get, the more they become sucked up by creatures such as mussels and crabs like sponges. Chemicals leak out into the surrounding muscle tissue. We have seen inflammation responses from crabs, stress reflexes.
Then they get into the food chain of higher-level animals and humans. That still has to be researched.
The interviews were conducted by Melanie Hall.