Simulation tracks Covid-related plastic waste around the world’s oceans
Image credit: Dreamstime
The amount of single-use plastic pollution created by the Covid-19 pandemic, such as face masks, gloves, and face shields, is intensifying pressure on an already out-of-control global plastic problem, a study has found.
While many other studies have suggested that there will be a massive influx of Covid-related mismanaged plastic waste, the researchers from the University of California San Diego (UC San Diego) believe their project is the first to assess the magnitude of the waste that will enter the oceans.
It uses a newly developed ocean plastic numerical model to quantify the impact of the pandemic on plastic discharge from land sources.
Using the model, the researchers found that more than eight million tons of pandemic-associated plastic waste has been generated globally, with more than 25,000 tons entering the global ocean.
Within three to four years, a significant portion of this ocean plastic debris is expected to make its way onto either beaches or the seabed. A smaller portion will go into the open ocean and will eventually be trapped in the centres of ocean basins or subtropical gyres, becoming floating garbage patches.
The researchers incorporated data from the start of the pandemic in 2020 through August 2021, finding that most of the global plastic waste entering the ocean is coming from Asia, with hospital waste representing the bulk of the land discharge. The study reveals the need for better management of medical waste in developing countries.
“When we started doing the math, we were surprised to find that the amount of medical waste was substantially larger than the amount of waste from individuals, and a lot of it was coming from Asian countries, even though that’s not where most of the Covid-19 cases were,” said study co-author Amina Schartup, an assistant professor at Scripps Oceanography in UC San Diego.
“The biggest sources of excess waste were hospitals in areas already struggling with waste management before the pandemic; they just weren’t set up to handle a situation where you have more waste.”
Yanxu Zhang, a professor from Nanjing University that also worked on the study, said their plastic waste model was built based on Newton’s laws of motion and the law of conservation of mass.
“The model simulates how the seawater moves driven by wind and how the plastics float on the surface ocean, degraded by sunlight, fouled by plankton, landed on beaches, and sunk to the deep,” he said. “It can be used to answer ‘what if’ questions, for example, what will happen if we add a certain amount of plastics to the ocean?”
The researchers found that most of the global plastic waste from the pandemic is entering the ocean from rivers. Asian rivers account for 73 per cent of the total discharge of plastics, with the top three contributors being the Shatt al-Arab, Indus, and Yangtze rivers, which discharge into the Persian Gulf, Arabian Sea, and East China Sea. European rivers account for 11 per cent of the discharge, with minor contributions from other continents.
While most of the pandemic-associated plastics are expected to settle on beaches and the seafloor, a smaller amount is likely to end up circulating or settling in the Arctic Ocean, which appears to be a “dead-end” for plastic debris transported into it due to ocean circulation patterns, the authors said.
The model shows that about 80 per cent of the plastic debris that transits into the Arctic Ocean will sink quickly, and a circumpolar plastic accumulation zone will be formed by around 2025, the study predicts.
The Arctic ecosystem is already considered to be particularly vulnerable due to the harsh environment and high sensitivity to climate change. The potential ecological impacts of exposure to accumulated Arctic plastics adds another layer of concern, the researchers added.
To combat the influx of plastic waste into the oceans, they urged better management of medical waste in epicentres, especially in developing countries and also called for global public awareness of the environmental impact of personal protection equipment (PPE) and other plastic products.
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