Discarded face masks harming aquatic systems, disrupting carbon capture

Disposable face masks have become a major source of pollution since the COVID‑19 pandemic. Globally, million of tons of material from discarded masks are making their way into coastal waters, with usage driven by hazards such as wildfire smoke and surges in respiratory viruses.

Discarded masks slowly release plastic fibres and chemicals into oceans, rivers, and lakes. And because of their fibrous texture, they also soak up other harmful chemicals already in the water.

Researchers from Memorial University of Newfoundland (MUN) used the CLS to study how marine life is affected by this mask debris and a class of flame-retardant chemicals called PBDEs, which are known to be toxic, long lasting, and stick easily to plastics.

The scientists found that when PBDEs stick to mask material, their harmful effects can change and, in some cases, become worse. Several types of microalgae grew more slowly and had trouble carrying out photosynthesis, which is how they make energy from sunlight. These effects varied depending on the type of algae and how old or broken down the mask material was. Fish embryos exposed to this pollution “cocktail” also showed more developmental problems.

Dr. Xing Song, Postdoctoral Research Fellow with MUN’s Northern Region Persistent Organic Pollution Control (NRPOP) Laboratory, says the team’s findings -- published in the journal Water Research -- matter because damage to microalgae can spread through the entire aquatic food web.

If microalgae grow less, there is less food for fish and other marine life. Microalgae also play a major role in removing carbon dioxide from the atmosphere. Reducing their activity could weaken the ocean’s ability to help slow climate change.

“Our findings show that these co-contaminants can affect microalgae, fish embryos, and key ecological functions in aquatic systems,” says Song. “Because microalgae support food webs and contribute to carbon fixation, these impacts may have broader implications for ecosystem health. This is a big problem for the whole ecological system.”

The researchers used two CLS beamlines to measure the concentration of flame retardant absorbed by masks and to track changes in the microalgae’s internal chemistry.

Dr. Baiyu Zhang, professor in MUN’s Faculty of Engineering and Applied Science, says the synchrotron was critical to their work. “We had several questions we were trying to answer – about their (masks and PBDEs) co-contamination behaviour, their toxicity, and their impact on microalgae,” says Zhang. “The CLS gave us a huge amount of data, which we then used machine learning to analyze to extract this important information.”

Song says the study highlights the importance of proper mask disposal to protect water, wildlife, and long‑term ecosystem health. “We know that it may take masks over 10 years to completely disappear from the environment, so the harmful, negative effects we’ve identified are persistent and long term.”

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Song, Xing, Yiqi Cao, Baiyu Zhang, Rebecca Mesburis, Scott Rosendahl, Benjamin de Jourdan, Qiao Kang et al. "Disposable Face Masks and PBDEs in Aquatic Environments: Co-contamination and Impacts." Water Research (2026): 125874. https://doi.org/10.1016/j.watres.2026.125874