The world’s reliance on plastics is overwhelming the planet and in particular, the oceans. It has been found inside the digestive tracts of sea turtles, sea birds and whales, even gumming up the insides of plankton that many larger sea creatures feed on. We see horrible images and videos of what the plastic does to our fellow inhabitants of this world. A gut-wrenching video of a plastic straw being removed from the nostril of a sea turtle. A dead albatross on a remote Pacific atoll, its stomach bursting with plastic caps and other small plastics that the bird had believed was food, and who had been fed to her chicks where they too succumb from starvation and digestive issues. Seals, sharks, and marine mammals are snared in discarded fishing nets. Just ugh!!
It’s only been 70 years since humans have been using plastics and we do not know all the ways that the mounting debris on our coastlines and floating in giant patches in the oceans is affecting us, notes the press release.
Plastic is useful for people, it’s durable and lightweight and convenient. It’s made of the same material, petroleum, that is destroying our climate by heating the planet with greenhouse emissions when burned as fuel. These gases affect sea level, global temperatures, cyclones, flooding and drought across the planet.
Now University of Hawaiʻi at Mānoa School of Ocean and Earth Science and Technology (SOEST) researchers have discovered that during common plastic degradation, several greenhouse gases are emitted. The study was published in PLOS One.
From the press release by the University of Hawaii:
The study, published in PLOS One, reports the unexpected discovery of the universal production of greenhouse gases methane and ethylene by the most common plastics when exposed to sunlight. The SOEST team tested polycarbonate, acrylic, polypropylene, polyethylene terephthalate, polystyrene, high-density polyethylene and low-density polyethylene (LDPE)—materials used to make food storage, textiles, construction materials and various plastic goods. Polyethylene, used in shopping bags, is the most produced and discarded synthetic polymer globally, and was found to be the most prolific emitter of both gases.
The team found that the emission rate of the gases from virgin pellets of LDPE increased during a 212-day experiment, and that LDPE debris found in the ocean also emitted greenhouse gases when exposed to sunlight. Once exposed to solar radiation, the emission of these gases continued in the dark.
“We attribute the increased emission of greenhouse gases with time from the virgin pellets to photo-degradation of the plastic, as well as the formation of a surface layer marked with fractures, micro-cracks and pits,” said lead author Sarah-Jeanne Royer, a post-doctoral scholar in the Center for Microbial Oceanography: Research and Education (C-MORE) during the study. “With time, these defects increase the surface area available for further photo-chemical degradation and therefore contribute to an acceleration of the rate of gas production.”
The researchers note that it is polyethylene, “a tough, light, flexible synthetic resin made by polymerizing ethylene, chiefly used for plastic bags, food containers, and other packaging” that is the chief emitter of the greenhouse gases methane and ethylene.
University of Hawaii researcher Sarah-Jeanne Boyer is now working on estimating the amount of plastics, particularly single-use plastics, “exposed to the environment in oceanic and terrestrial regions, globally, in order to constrain the overall greenhouse gas emissions from plastics”.
Engineering and Technology reported on the study and has additional information not included in the University’s press release.
For further reading.
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The discovery of microplastics in the Antarctic fjords could have disastrous repercussions on the environment