Polystyrene persists in the environment for millennia, based on some international governmental agencies. This estimate is based on the time required for microbes to break down the plastic. However, now researchers have challenged this common assumption with the discovering that polystyrene can be broken down by sunlight over a much shorter time scale.
Polystyrene Utilized in many consumer and industrial products, similar to food containers, protective packaging, and constructing materials; polystyrene broadly contaminates the environment. Common microbes can’t degrade the polymer due to its aromatic backbone, leading scientists to conclude that it endures for tens of thousands of years. Collin Ward and associates wondered whether sunlight absorbed by polystyrene might transform it into carbon dioxide gas and dissolved organic carbon in less time.
To find out, the researchers placed five commercially available polystyrene samples into the water and exposed them to simulated sunlight, which was three times brighter than sunshine at the equator. The researchers discovered that the simulated sunlight partially oxidized all five samples to dissolved organic carbon. They calculated that, for latitudes 0° to 50° N, this process would take decades. Complete oxidation of polystyrene to carbon dioxide by sunlight would require centuries, they estimate. The polystyrene samples degraded at different charges depending on the additives they contained, which in the future might be manipulated to control the lifetimes of the plastics, the researchers say.
The authors acknowledge funding from the Frank and Lisina Hoch Endowed Fund, the Andrew W. Mellon Foundation, the Stanley Watson Chair in Oceanography and the National Science Foundation Graduate Research Fellowship.