Tracking plastic in the deep sea: how the Levant Basin (East Mediterranean) became a sink for packaging waste
A new study reveals how plastic bags aren't just polluting our beaches but also their sinking mechanisms to the deepest parts of the Mediterranean deep sea
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Left: Deep-sea research cruise conducted in 2022. Right: Onboard sampling activities and field observations during the expedition
view moreCredit: 2022 deep-sea cruise group
A groundbreaking new study has uncovered the Levant Basin as one of the world's most concentrated graveyards for plastic packaging and the mechanisms that help the plastic sink down to the seafloor.
The study, led by the PhD student Xing-Yu Li and Prof Revital Bookman from the University of Haifa, and Dr Yael Segal from Israel Oceanographic and Limnological Research (IOLR), was recently published in Marine Pollution Bulletin and shows for the first time how the southeastern Mediterranean’s Levant Basin hosts some of the highest recorded deep-sea densities of plastic litter. “We used trawls to survey the seafloor and we mainly found plastic bags and packaging that dominate the debris.” says Xing-Yu Li, the leading author of the paper. “We were then curious to understand how the lightweight material, the plastic debris, are transported offshore and sink to the seafloor. We kept asking, what information can each recovered item really tell us?”, continues Xing-yu, “and to answer that we used a multi-marker analysis. In the multi-marker approach anything that is found on a piece of plastic is an evidence. We extracted as many evidnece as possible from every piece of waste, more than many previous studies, to build a fuller, more detailed view of the bottom waste.”
The multi-marker approach is a new framework that can link items such as the size, color, integrity, shape of the collected debris, polymer/additives (e.g., CaCO3), and surface attachments (for example biofilm, tar, minerals) to buoyancy behavior and depth patterns across a large dataset. This novel integrative approach takes the so far “counting” approach (i.e. counting the number of collected plastic debris) to a whole new level of mechanism-oriented evidence for tracing the debris source, offshore export and deep deposition of thin-film plastic packaging. It is the first time that a research evaluated the buoyancy of microplastic collected from the deep sea.
Research findings reveal that the Levant Basin in the southeastern Mediterranean is a major global hotspot for plastic pollution, with extremely high seafloor concentrations of plastic bags and packaging. Furthermore, a “hot belt” of accumulation was found at the edge of the continental shelf (200 m), while the bathyal plain (>1000 m) acts as a final sink due to high pressure and sedimentation. Plastic bags and packaging were mostly polyethylene, some containing CaCO₃ additives that sink closer to shore, while deeper basin plastics lacked such ballast and showed limited biofilm growth due to oligotrophic conditions. Instead, adhesion of sediments, shells, and especially tar enhanced their sinking and stability on the seabed. Although many PBPs could regain buoyancy if disturbed, resuspension is limited, making the deep basin a unique repository for this waste. Sources include land-based inputs (notably Egypt, Israel, and Turkey) and in the deep basin shipping disposals. Fisheries contribute, surprisingly, little probably due to strict Israeli regulations.
"It’s fascinating in the worst possible way,” says Prof Revital Bookman, “The eastern Mediterranean is quietly turning into a deep-sea landfill. Plastics that we use for only a few minutes are ending up trapped for centuries, threatening deep marine ecosystems we barely understand."
Dr Yael Segal says that “As the head of the national monitoring program, I see firsthand how plastic pollution is impacting the entire sea environment: beaches, water, sea bottom, and even local turtle populations.” According to the monitoring findings, plastic debris at the sea bottom are known worldwide yet the mechanism was not known. “For years in our monitoring reports we have reported a high concentration of plastic debris in this area. It was an unsolved mystery as we know that plastic debris should remain floating on the sea surface. Now we have a deep understanding of how it happens. The Eastern Mediterranean is the most polluted area in the world, and we must take action for the sake of the next generation.”
While plastic packaging constitutes the majority of global plastic usage, there are emerging evidence that plastic films are transported offshore and ultimately accumulate at depth. As a result, they carry significant implications for the health of benthic habitats and for establishing accurate regional plastic mass balances. Furthermore, the observed interaction between plastic debris and tar residues may prompt a reassessment of the fate and transformation pathways of marine pollutants. “This previously overlooked dynamic necessitates a broader perspective on pollution processes in marine environments”. Says Prof Bookman.” Without systematic deep-sea accounting, we risk underestimating the true environmental footprint of plastic pollution and misallocating mitigation efforts by neglecting offshore and deep-sea sinks. In this context, coordinated basin-wide monitoring and management across countries that share the sea, including Egypt and Turkey, are essential for designing integrated strategies that address transboundary pollution and improve mitigation efficiency”.
Plastic packaging retrieved from the seafloor at depths of 200–1300 m, with identifiable barcodes enabling source attribution
Credit
Xing-yu Li
Top: Benthic plastic bags with adhered tar, cut into standardized shapes for analysis. Bottom: Binocular microscope images showing surface morphology of the corresponding samples
Credit
SedLab, university of Haifa.
Journal
Marine Pollution Bulletin
Method of Research
Meta-analysis
Article Title
Unveiling the levant basin as a unique sink for plastic bags and packaging through comprehensive multi-marker analysis
Nanoplastics detection chip revolutionizes plastic pollution monitoring
A first-of-its-kind method that’s cheap, portable and powerful in detecting harmful nanoplastics particles has been developed by an international consortium of researchers, with far-reaching implications for global health and environmental science
A first-of-its-kind method that’s cheap, portable and powerful in detecting harmful nanoplastics particles has been developed by an international consortium of researchers, with far-reaching implications for global health and environmental science.
While the dangers of microplastics are widely recognised, smaller nanoplastics are more insidious, infiltrating food, water, and even human organs, and detecting them has been difficult and expensive.
Described in a paper published today in Nature Photonics, researchers at the University of Melbourne and the University of Stuttgart in Germany have developed a novel “optical sieve” to cost-effectively detect, classify and count nanoplastic particles in real-world environments.
Dr Lukas Wesemann, who led the Australian arm of the research at the University of Melbourne, said the innovation is able to expose the extent of nanoplastics pollution that can persist for centuries, and provides hope for scalable monitoring of this global environmental and health crisis.
“Until now, detecting and sizing plastic particles with diameters below a micrometre – one millionth of a metre – has relied on costly tools such as scanning electron microscopes, and been nearly impossible outside advanced laboratories, leaving us blind to their true impact,” Dr Wesemann said.
“Our novel optical sieve is an array of tiny cavities of varying sizes in a gallium arsenide microchip.”
When a liquid containing nanoplastics is poured over the sieve, each plastic particle is captured in a void of matching size, sorting them into categories down to a diameter of 200 nanometres.
“Crucially, it requires only an optical microscope and a basic camera to observe distinct colour changes to light reflecting off the sieve, which allows us to detect and count the sorted particles,” Dr Wesemann said.
University of Melbourne Associate Professor Brad Clarke and co-author said the invention could make pollution monitoring far more affordable, accessible and mobile.
“Understanding the numbers and size distribution of nanoplastics is crucial to assess their impact on global health, and aquatic and soil ecosystems,” he said.
“Unlike microplastics, smaller nanoplastics can cross biological barriers – including the blood-brain barrier – and accumulate in body tissues, raising profound health concerns of toxic exposure.”
The researchers validated the technique using lake water mixed with nanoplastics, with future testing potentially including identifying nanoplastics in blood samples.
“In contrast to existing methods like dynamic light scattering, our new method does not require separating the plastics from biological matter,” Dr Wesemann said.
The researchers are exploring scaling the innovation into a commercially available environmental testing solution.
The team included scientists from the Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems and Australian Laboratory for Emerging Contaminants in the School of Chemistry.
The research was supported by funding, including from the Australian Research Council, European Research Council, the Australia–Germany Joint Research Cooperation Scheme (Universities Australia-DAAD), the University of Stuttgart and the University of Melbourne.
Journal
Nature Photonics
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Optical sieve for nanoplastic detection, sizing and counting
Article Publication Date
8-Sep-2025
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