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New research reveals that PET-based glitter microplastics can actively influence biomineralization processes in marine environments, raising fresh concerns about the long-term environmental impact of microplastic pollution on marine ecosystems.

The research, led by a team from Trinity's School of Natural Sciences and in the journal Environmental Sciences Europe, shows that these microplastics promote the crystallization of calcium carbonate (CaCO₃) minerals, potentially affecting the growth and stability of marine calcifying organisms.

The study mimicked seawater conditions and investigated six different types of PET glitter to determine how their surface properties influence the formation of Ca-Mg carbonate minerals. Using advanced analytical techniques, including scanning electron microscopy and infrared spectroscopy, the researchers found that glitter microplastics provide sites for CaCO₃ crystallization, accelerating mineral formation and potentially altering skeletal structures in marine organisms.

Additionally, the researchers performed experiments that showed surface crystallization on glitter can occur within hours or even minutes. This rapid process may also accelerate microplastic degradation, increasing the release of harmful particles into marine environments.

"Our findings suggest that PET glitter can serve as artificial templates for calcium carbonate formation, which may have unintended consequences for marine life," said Kristina Petra Zubovic, lead author of the study. "This process could influence the structural integrity of marine organisms that rely on stable conditions for biomineralization."

Beyond promoting crystallization, the study also found that PET glitter undergoes physical degradation during mineral formation, leading to increased fragmentation and the release of smaller microplastic particles into the environment. This raises further concerns about the long-term ecological implications, as smaller microplastics are more easily ingested by marine organisms, potentially disrupting food chains and biogeochemical cycles.

"Microplastic pollution is an urgent global issue, and our study provides new insights into how these synthetic materials interact with natural mineralization processes," said Dr. Juan Diego Rodriguez-Blanco, the study's Principal Investigator, Associate Professor of Nanomineralogy in Trinity.

"Understanding these interactions is essential for assessing the broader environmental consequences of microplastic contamination in marine ecosystems. This research highlights the need for further investigations into the role of microplastics in biomineralization and their broader impact on marine biodiversity. As microplastics continue to accumulate in the world's oceans, studies like this provide critical knowledge to inform environmental policies and mitigation strategies."

What have the researchers discovered?

Glitter is widely used in cosmetics, arts and crafts, fashion, and holiday decorations to add sparkle and shine. It is also used in industrial applications, such as automotive paints, textiles, and anti-counterfeiting materials. Its versatility makes it popular across many industries, but its small size and plastic composition raise environmental concerns.

This material is made of shiny plastic pieces with sizes of 0.5 mm or smaller, with multiple layers. The main component of glitter is known as PET (polyethylene terephthalate) and is a strong, lightweight plastic commonly used in packaging, and textiles. It is durable and resistant to water but persists in the environment, contributing to plastic pollution.

However, glitter is made of a plastic base of PET coated with very thin layers of metals and color dyes to make it reflective. This layered structure makes it more durable, but also harder to break down in the environment. Most glitter waste eventually makes its way into seawater due to its small size, lightweight nature, and widespread use, making it difficult to capture in waste management systems.

The researchers discovered that PET-based glitter microplastics can actively promote the crystallization of calcium carbonate (CaCO₃) minerals in seawater. Their experiments revealed that the surface properties of these microplastics, particularly their irregular textures and functional chemical groups, create favorable sites for mineral crystallization. This means that when PET glitter is present in seawater, calcium carbonate forms more readily on its surface, potentially influencing the natural biomineralization processes of marine organisms that rely on CaCO₃ to build their shells and skeletons.

In addition to promoting crystallization, the study found that glitter microplastics undergo structural changes during the mineral formation process, leading to cracks, peeling, and the release of smaller micro- and nanoplastic fragments, even as small as 0.001 mm. This suggests that microplastics not only interact with mineralization but may also degrade more rapidly in marine environments, contributing to the spread of even smaller plastic particles.

Such findings raise concerns about the broader environmental consequences of microplastic pollution, particularly how it may impact marine ecosystems and calcifying organisms by altering natural mineral formation and increasing the bioavailability of microplastics.