Plastic debris dropped into the ocean can travel hundreds of miles while sinking

Floating islands of garbage composed of discarded or drifting plastic debris on the ocean’s surface are a common and visible reminder of the world’s plastic pollution problem. However, researchers believe that a significant portion of plastic waste might be sinking deeper into the ocean, making it harder to spot and understand the full scope of the issue. 

A new study published in ACS’ Environmental Science & Technology provides insight into the behavior of lightweight plastic particles in the Mediterranean Sea, suggesting that they can drift farther underwater than previously thought.

The ocean’s plastic pollution crisis is not limited to unsightly floating garbage patches. Animals can become trapped in or mistakenly consume plastic debris, and as the waste breaks down in the water, it can release harmful organic pollutants. 

While researchers have found lightweight plastic particles, typically measuring 5 millimeters or less, as deep as half a mile below the ocean’s surface, there is still much to learn about the behavior of sinking plastic. 

How the study was done

The prevailing assumption has been that plastic falls straight down from the surface. However, Alberto Baudena and his colleagues believed that lightweight plastic might not follow such a direct path.

To challenge this assumption, Baudena’s team employed an advanced computer model designed to track plastic at sea. They incorporated extensive data previously collected on floating plastic pollution in the Mediterranean Sea into their model. By simulating nearly 7.7 million bits of plastic distributed across the sea, they were able to track the virtual paths of these particles to depths as great as half a mile.

The researchers’ findings suggest that the slower the plastic particles sink, the farther they are carried from their points of origin by ocean currents. The slowest particles traveled an average of roughly 175 miles laterally. 

What the researchers found about ocean plastic debris

Comparing their simulation results with limited observational data on plastic distribution underwater, the team found their findings to be in agreement with the available data in the Mediterranean Sea.

Furthermore, their simulations revealed that ocean currents may push plastic waste toward coastal areas, with only about 20% of pollution near coasts originating from the nearest country. 

The long journeys these plastic particles undertake imply that they have an increased potential to interact with and harm marine life.

This study, funded by the International Union for Conservation of Nature, the Tara Expeditions Foundation, and the Albert II Monaco Foundation, sheds light on the behavior of lightweight plastic particles in the ocean and highlights the need for further research and action to combat the plastic pollution crisis.

More about plastic pollution in the ocean

Plastic pollution in the ocean is a growing global concern that poses significant threats to marine ecosystems, biodiversity, and even human health. Every year, millions of tons of plastic waste enter the oceans, originating from land-based sources such as litter, industrial manufacturing, wastewater runoff, and improper waste disposal. 

Some of the most common plastic pollutants include single-use plastics, such as bags, bottles, and straws, as well as microplastics, which are tiny plastic particles smaller than 5 millimeters in size.

There are several ways in which plastic pollution affects the marine environment:

Entanglement and ingestion

Marine animals, such as sea turtles, whales, dolphins, seals, and birds, can become entangled in plastic debris, leading to injury, impaired movement, or even death. Additionally, many marine species may mistake plastic particles for food, resulting in ingestion. This can cause internal injuries, blockages in the digestive system, malnutrition, and death.

Habitat destruction

Accumulation of plastic debris on the ocean floor and along coastlines can lead to the destruction of vital marine habitats, such as coral reefs and seagrass meadows, affecting the survival of various marine species.

Microplastics and Nanoplastics

As plastic debris breaks down into smaller particles, it forms microplastics and nanoplastics, which can be ingested by smaller organisms like plankton. These tiny particles can then make their way up the food chain, ultimately reaching humans who consume seafood.

Chemical pollution

Over time, plastic waste releases toxic chemicals such as bisphenol A (BPA) and phthalates, which can leach into the surrounding water. These chemicals have been linked to a range of health problems in both marine life and humans, including endocrine disruption, reproductive issues, and developmental abnormalities.

Transport of invasive species

Floating plastic debris can serve as a means for invasive species to hitch a ride, allowing them to colonize new areas and disrupt local ecosystems.

Economic impact

Plastic pollution negatively affects industries such as tourism, fishing, and shipping, leading to significant economic losses. For instance, beach cleanups and damage to fishing equipment can be costly.

Efforts to address plastic pollution in the ocean include reducing plastic production and consumption, improving waste management and recycling systems, promoting the use of alternative materials, and raising public awareness about the issue. 

Initiatives such as the Ocean Cleanup project and the Global Ghost Gear Initiative focus on removing plastic debris from the ocean, while numerous international agreements, including the United Nations’ Sustainable Development Goals, emphasize the need to preserve and protect marine environments.

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