Although more than ten million tons of plastic waste is dumped into the seas and oceans each year, in reality we see only 1% of it, which is the part that floats just above the surface.
What happened to the remaining 99% of plastic waste? What if these "great oceanic litter patches" were just the tip of the iceberg? Or the tip of the iceberg?
An international team of British, German and French researchers found an answer to these questions, and in their study published in the famous scientific journal "Science" on April 30th, they confirmed that strong marine currents lead micro-plastic materials known as microplastics along the sea floor to large "drifts", It is concentrated there in amazing quantities.
The research team found about 1.9 million pieces of microplastics in a layer of 5 cm thick and covering only one meter, the highest level of microplastic ever recorded on the ocean floor.
Influence of water currents.
The microplastic was found on the sea floor all over the world, and scientists were not sure how it got there and how it spread.
Scientists thought it would separate by size or density in a similar way to natural sediments, but the microplastic is somewhat different, some float, but more than half drown.
It is known that large pieces of plastic gradually degenerate into smaller fragments in the ocean, until micro-plastic particles smaller than 5 mm form over time due to the influence of natural factors.
Floating plastics may be drowned as soon as they are covered with algae, or if they are associated with viscous minerals and other organic materials.
|Microplastics in river sediments (Wikipedia)|
Recent research has shown that rivers transport the microplastic to the ocean as well, and laboratory experiments have revealed that giant avalanches can transfer these fine particles along the deep sea canyons to greater depths.
The researchers discovered how a global network of marine currents is transported in the depth of the micro-plastic seas, creating hot plastic points within the vast sediments drifts. By riding these currents, micro-plastic accumulates in the deep sea where life forms are abundant.
During the study, the researchers surveyed an area of the Mediterranean Sea off the western coast of Italy, known as the Tyrrhenian Sea, and studied the underwater currents that flow near the sea floor.
These currents are driven by differences in the salinity of water and temperature, and the erosion of sediments on the sea floor can reach several kilometers with a height of hundreds of meters, and ends where these currents lose their strength.
The researchers analyzed sediment samples from the sea floor taken from several depths up to hundreds of meters, separated the microplastic from the sediments in the laboratory, then counted them under microscopes, and analyzed them using infrared spectroscopy to find out the types of plastic polymers in them.
The researchers found that most of the microplastics found on the sea floor are fibers of clothing and textiles, and this particularly malignant species can be eaten and absorbed by living organisms.
|Plastic debris decomposes, sinks to the ocean floor and sweeps the ocean currents in vast drifts.|
Although the microplastic on its own is often non-toxic, studies show that buildup of toxins on its surfaces can harm organisms if ingested.
Deep ocean currents also carry oxygenated water and nutrients, which means that the seafloor hotspots where microbes accumulate may also be home to important ecosystems such as deep-sea coral reefs that have evolved to rely on these flows, but now receive vast amounts of micro-plastic.
A hidden problem Microplastic
is a type of sustainable pollution that has a negative impact on ecosystems, especially marine ones.
|Microplastics threaten important ecosystems such as deep-sea coral reefs (Wikipedia)|
What the researchers discovered was a hidden problem. Natural currents and the flow of plastic waste into the ocean transform parts of the seabed into huge reservoirs of fine plastic waste.
Scientists have found that clothes that can last only for weeks in your wardrobe still contaminate seafloor and ocean beds for long periods of time, possibly up to centuries, which could harm the unique living creatures that live there.