What The introduction of plastic debris into the ocean has created a new ecological niche named the Plastisphere. This niche at the plastic surface hosts a complex biofilm constructed of bacteria, fungi, organic debris, minerals, metals, and salts. The Plastisphere influences the transport of plastic particles, and harbors colonizers and plastic-degrading microorganisms. It is the point of contact between the plastic and its environment and as such, the complex structure of the Plastisphere creates a highly reactive surface. Metals and minerals are formed on the plastic surface or embedded in the biofilm matrix. On many surfaces, minerals and metals support biological attachment and function as catalysts. This study will explore the role of the Plastisphere minerals and metals to track plastic influence on biological processes and to probe pathways of plastic stability or degradation in the coastal marine environment. Why We live on a blue planet. The ocean delivers invaluable ecosystem services, provides food, jobs, recreation, and is a treasure of biodiversity. Images of plastics lining beaches, entangling coastal plants, and choking sea life, however, fill our newsfeeds and threatens the health of our oceans. Besides strategies to reduce plastic, research focuses on unraveling how plastic interacts with marine life and breaks down over time. This project will investigate an understudied component of the Plastisphere, the minerals and metals on plastic surfaces. This study will inform on the role of metals and minerals in the fate of plastic in the coastal marine realm. How This project has two main areas of focus, mineral-plastic surface interaction and mineral-influenced plastic degradation. In the first, mineral-surface interactions will be studied across scale; how minerals form and influence microbial attachment (µm scale) on plastic debris (cm scale cups, bags) and how nanoplastics (nm) adhere to or aggregate with mineral-shelled microorganisms (µm scale). In the second, we will track whether minerals influence plastic degradation by testing metal oxides as catalysts for plastic degradation. We will also use reactors to simulate how plastic breaks down in marine mud over time and quantify the carbon dioxide and methane gasses released. To this end, we will combine advanced microscopy methods with microbiological, geochemical and mineralogical approaches in the laboratory.