There is a lot of plastic waste floating around in the world's oceans, and the North Sea is no exception. Scientists have now found that most of the coastal marine plastic in the southern North Sea comes from Germany - mostly from municipalities and fisheries. In some places in the ocean, the plastic waste also forms more concentrated accumulations, as the scientists report. They recommend educational campaigns and partial bans on single-use plastic to reduce waste.
The oceans are full of plastic. According to the United Nations Environment Program, there are now up to 18,000 pieces of plastic of various sizes floating on every square kilometer of sea surface. In some places, such as the "North Pacific Garbage Patch" between Hawaii and California, gigantic garbage patches have even formed. Tens of thousands of tons of plastic waste are floating in them, which only decompose slowly and endanger entire ecosystems.
Population helped with the plastic count
However, to take effective action against plastic pollution in the oceans, we must first understand where plastic comes from and how it spreads in the water. Researchers led by Jens Meyerjürgens from the Carl von Ossietzky University of Oldenburg have now determined exactly that for the southern North Sea. To do this, they recorded plastic waste on the coast, in estuaries and on the sea floor, calculated the paths of virtual waste particles with special models and exposed drift bodies with satellite transmitters, which - like real waste - drifted on the sea surface and continuously transmitted their positions.
The team even went so far as to throw their own "garbage" into the sea to better understand its movement patterns. It was about 63,000 environmentally friendly wooden tablets with an edge length of eight by ten centimeters, which Meyerjürgens and his colleagues distributed both on the open sea and at various locations on the coast. The special thing about it: Anyone who found such a small tablet washed up on the coast - regardless of whether they were scientists or not - could report their discovery via an online portal. In addition, the research team analyzed various stakeholders such as tourism, fisheries, industry and ports.
Garbage doesn't float far in the river
The result: Most of the plastic waste in the North Sea comes from fishing and from municipalities, as Meyerjürgens and his colleagues found out. Accordingly, larger communities on the North Sea coast and at the mouths of the Elbe, Weser and Ems contribute a significant part of the plastic. But what ends up in the water doesn't always get very far, as the wooden plaques left in the rivers show. Most of these were simply washed up again at another point on the river bank and did not even reach the open sea. In the Elbe, this was the case for half of the tablets, in the Ems for almost 90 percent.
In general, two-thirds of the wooden plaques released in rivers and on coasts only covered a distance of 25 kilometers before they landed on the shore again. Only a fifth of them traveled more than 50 kilometers, according to the scientists. The wooden tablets that Meyerjürgens and his team had deployed on the open sea, on the other hand, covered the longest distance: a third of them had traveled more than 250 kilometers before returning to shore.
Germany is one of the main culprits
The garbage in the North Sea could also be traced back to different countries. Meyerjürgens and his colleagues discovered, for example, that most of the garbage in coastal areas of the North Sea can be traced back to Germany and the Netherlands. According to this, 47 to 61 percent of the coastal plastic comes from Germany. In the open sea, on the other hand, the amounts of garbage from Germany are negligible, according to the team. There, the Netherlands is one of the main causes with a share of 15 to 23 percent, together with Great Britain and France.
However, the research team was not able to identify any garbage patches in the North Sea, such as those found in the North Pacific. Nevertheless, the scientists discovered places where the garbage was more concentrated than elsewhere, so-called oceanographic fronts. “These are zones where, for example, freshwater from a river meets salty seawater. It's often very turbulent there," explains Meyerjürgens. Data from the larger, satellite-tracked drifters shows that the devices often got stuck on such fronts for days or even weeks, before the wind finally blew them away. Accordingly, more plastic particles that had sunk to the bottom were found on the seabed below the fronts than elsewhere.
Campaigns and less single-use plastic recommended
In order to reduce the amount of plastic waste that ends up in the North Sea in the future, the research team recommends various measures. The most promising thing would be to ban single-use plastic, such as drinking cups or cutlery, at larger community events. In addition, stricter storage conditions in ports make sense, since port operations alone are responsible for around eight percent of the plastic waste in the North Sea. The researchers also consider campaigns to raise general awareness of the waste problem to be important. In her opinion, fisheries should be included more than in the past.
Source: Carl von Ossietzky University of Oldenburg, Article: Frontiers in Marine Science, doi: 10.3389/fmars.2023.1148714