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Plastic photodegradation under simulated marine conditions
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Researchers measured the photodegradation rates of different plastic types under simulated marine conditions and found that UV radiation caused all plastics to release dissolved organic carbon and greenhouse gases including methane. The degradation rates translated to 1.7-2.3% per year for particles in subtropical surface ocean conditions. Modeling suggests that solar UV radiation may have already degraded 7 to 22% of all floating plastic ever released into the sea.
Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7-2.3 % yr of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea.
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Researchers investigated how ultraviolet radiation drives the photolytic degradation of microplastics ranging from 1 micron to 5 mm, measuring greenhouse gas emissions produced as plastics fragment and oxidize under UV exposure. Photolysis was shown to both fragment microplastics and release gases including methane and ethylene, linking plastic degradation to climate-relevant emissions.
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Common ocean surface microplastics (PE, PP, EPS) were irradiated under simulated sunlight, which fragmented and oxidized the polymers and produced dissolved organic carbon as a significant byproduct. The study identifies sunlight-driven photochemical dissolution as an important but poorly quantified removal mechanism for buoyant microplastics from the ocean surface.
Photolysis of microplastics under ultraviolet radiation : greenhouse gas emissions.
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Researchers investigated the photodegradation of microplastics under UV radiation, measuring greenhouse gas emissions produced during polymer breakdown. The study found that microplastic photolysis releases carbon-based gases, adding a previously underappreciated contribution to atmospheric greenhouse gas budgets.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.