Microplastic-derived compounds form unstable heavy-metal complexes, making them highly reactive and prone to breaking down into harmful molecules. Digest
Pollution from microplastics and heavy metals has increased markedly in aquatic ecosystems in recent years, especially in industrial wastewater and municipal sewage, where these contaminants often coexist at high levels. As plastics break down into microplastics, they release organic compounds that behave differently from natural materials, especially when interacting with heavy metals. A recent study found that microplastic-derived organic matter, which makes up about 10% of surface ocean material in some regions, reacts with heavy metals in ways that could worsen environmental contamination.
Researchers compared natural organic matter from soil and water with organic matter released by degraded plastics like polyethylene, polypropylene, and polyvinyl chloride. They analyzed how these substances interact with cadmium, chromium, copper, and lead to understand differences in their chemical behavior and transformations.
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They found that natural organic matter forms stable bonds with metals, whereas microplastic-derived compounds form unstable complexes. These complexes are highly reactive, especially with chromium, which explicitly targets compounds in microplastic-derived matter, causing it to break down into smaller, hazardous molecules like benzene and phenol. Notably, microplastic-derived compounds had almost 30% more condensed aromatics, a type of chemical structure that makes them more vulnerable to breaking down when exposed to oxygen.
These findings suggest that plastic pollution worsens heavy metal contamination not only by adding pollutants but by changing how metal-organic complexes behave and move in the environment. Learn more about microplastics in our overview article.