According to some international governmental agencies, polystyrene remains in the environment for thousands of years. This estimate is based on the time microbes take to break down the plastic. Now researchers have challenged this common assumption by stating that sunlight can degrade polystyrene over a much shorter period of decades to centuries. They report their findings in Environmental Science & Technology Letters .
Many consumer and industrial products, such as food containers, protective packaging and building materials, use polystyrene, which is a major contaminant to the environment. Ordinary microbes can not degrade the polymer due to its aromatic backbone, which has led scientists to believe it will persist for tens of thousands of years. Collin Ward and colleagues from the Woods Hole Oceanographic Institution wondered if sunlight absorbed by polystyrene could turn it into carbon dioxide and dissolved organic carbon in much less time.
To find this out, the researchers placed five commercially available polystyrene samples in water and then exposed simulated sunlight that was three times brighter than the sunlight at the equator. The researchers found that the simulated sunlight partially oxidized all five samples to dissolved organic carbon. They calculated that this process would take decades for latitudes from 0 ° to 50 ° N (from the equator to the southern border of Canada). Complete oxidation of polystyrene to carbon dioxide by sunlight would, according to estimates, require centuries. The polystyrene samples decomposed at different rates, depending on the additives contained, which, according to the researchers, could be manipulated in the future to control the life of the plastics.
For more information on this study, see Scientists Who Thought It Took Thousands of Years The decomposition of plastic can only take decades.
Reference: "Sunlight converts polystyrene to carbon dioxide and dissolved organic carbon" by Collin P. Ward, Cassia J. Armstrong, Anna N. Walsh, Julia H. Jackson and Christopher M. Reddy, 1
DOI: 10.1021 / acs.estlett.9b00532
The authors confirm funding from Frank and Lisina The High Endowment Fund, the Andrew W. Mellon Foundation, the Stanley Watson Chair of Oceanography and the Graduate Research Fellowship of the National Science Foundation
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