The world’s plastic pollution problem is much worse than imagined, according to a new analysis published on 18 August in Nature Communications (1). Compared to previous estimates of around 17 million, the latest findings suggest the actual number of ‘invisible’ microplastics could be at least 10 times higher – that is, there may be around 200 million tonnes of microplastics in the Atlantic Ocean alone.
Ocean ecosystems are being destroyed by plastic waste. The presence of slowly degrading plastics in oceans poses threats to both humans and marine life, as well as the environment. Another recent study published earlier this year in Science suggested that if current trends continue, the amount of plastic waste entering oceans will triple over the next two decades (2).
To come up with the latest estimates, the scientists from the National Oceanography Centre (NOC) in the UK collected seawater samples between September and November 2016 during the 26th Atlantic Meridional Transect expedition. Then, they used a spectroscopic imaging technique to identify plastic contaminants in the top 200 meters of water, which amounted to between 12 and 21 million tonnes of three of the most common types of plastics: polyethylene, polypropylene and polystyrene. By assuming the concentration of plastic in the whole Atlantic is the same, the scientists were to come up with an estimate of more than 200 million tonnes in the Atlantic as a whole.
In a statement, lead author Dr Katsiaryna Pabortsava said: “Previously, we couldn’t balance the mass of floating plastic we observed with the mass we thought had entered the ocean since 1950. This is because earlier studies hadn’t been measuring the concentrations of ‘invisible’ microplastic particles beneath the ocean surface. Our research is the first to have done this across the entire Atlantic, from the UK to the Falklands.”
Co-author Professor Richard Lampitt believes that “in order to determine the dangers of plastic contamination to the environment and to humans we need good estimates of the amount and characteristics of this material, how it enters the ocean, how it degrades and then how toxic it is at these concentrations”.
The latest findings are part of a larger effort by the National Oceanography Centre to better understand the magnitude of marine plastics and the potential harms. Lampitt says that researchers currently have an ‘inadequate understanding’ and previous estimates of how much plastic is dumped into the ocean have been ‘massively underestimated’.
In their analysis, the researchers only looked at three of the most common types of plastic pollution in a limited size range. Considering the wide range of plastics currently in use, the problem is likely to be much worse. Another study published in May in the journal Environmental Pollution showed that microplastic pollution in the oceans –– which often go undetected – is likely to be vastly underestimated (3).
Increased public awareness of the plastic pollution problem and public initiatives such as carrier bag charges seem to have had little impact so far. Moreover, the coronavirus pandemic has triggered a surge in plastic waste. In another recent paper published in Environmental Science & Technology, the authors report an estimated global use of around 129 billion face masks and 65 billion gloves per month during the COVID-19 pandemic, which is resulting in widespread environmental contamination – and making its way into the oceans (4). Single-use plastics– much of it not recyclable – have reached epic proportions due to increased takeaway and other coronavirus precautions.
Pabortsava hopes the discovery will spur policymakers to consider what could be done to stop so much plastic reaching the seas, where it endangers marine life, she told the Guardian, adding that we still know too little about the potential dangers.
“We need to answer fundamental questions about the effects of this plastic, and if it harms ocean health. The effects might be serious, but might take a while to kick in at sub-lethal levels.”.
(1) Pabortsava, K. & Lampitt, R.S. High concentrations of plastic hidden beneath the surface of the Atlantic Ocean. Nature Communications (2020). DOI: 10.1038/s41467-020-17932-9
(2) Lau, W.W.Y. et al. Evaluating scenarios toward zero plastic pollution. Science (2020). DOI: 10.1126/science.aba9475
(3) Lindeque, P.K. et al. Are we underestimating microplastic abundance in the marine environment? A comparison of microplastic capture with nets of different mesh-size. Environmental Pollution (2020). DOI: 10.1016/j.envpol.2020.114721
(4) Prata, J.C. et al. COVID-19 Pandemic Repercussions on the Use and Management of Plastics. Environmental Science & Technology (2020). DOI: 10.1021/acs.est.0c02178