PLA plastic is biodegradable and biodegradable often used in disposable plates, glasses and cutleryPolystyrene does not degrade in the marine environment faster than plastics from petroleum such as polyethylene or polystyrene.
This is culminated in a study led by the Barcelona Institute of Marine Sciences (ICM-CSIC), with participation from Vigo’s Institute for Marine Studies (IIM-CSIC), which publishes the journal. Marine Environmental Studies.
Previous studies have shown that such plastics do not biodegrade below 60º C, conditions that do not occur in the oceanThis is not the case, although experts would expect it to be more susceptible to photodegradation caused by sunlight and the resulting products to be easier for marine bacteria to degrade.
The biodegradability of plastic does not mean that it will degrade under all conditions.. For example, compostable plastic needs temperatures in excess of 50ºC to biodegrade, and that doesn’t happen in the ocean or in many other natural environments,” warned ICM-CSIC researcher Cristina Romera-Castillo.
To perform the study, the researchers exposed different types of plastic to the ocean’s temperature and solar radiation conditions and analyzed the organic carbon they released as a result of their degradation, as well as measuring the ability of marine bacteria to break down that carbon. .
Thus, the biodegradable plastic PLA does not release more carbon than plastic derived from petroleum, and Marine bacteria are equally or less effective at breaking down PLA photodegradation products than, for example, polystyrene.
Old plastic pollutes more
Laboratory experiments also revealed that old plastic is getting much more polluted again.
Specifically, the results show that plastic dumped into the sea will release 57,000 tons of dissolved organic carbon each year; that’s more than double what previous studies with new pieces of plastic suggest.
“This is because plastic loses additives that protect it from degradation by the action of sunlight and erosion, which releases more chemical compounds in the water, whether from the polymer itself or from the forming additives, which give the plastic color, flexibility and other properties,” Romera detailed.
All of this was gathered in another study, recently published in the journal “Frontiers of Marine Science,” in which researchers warned of the impact on the marine ecosystem and the carbon cycle.
The good news is that there are bacteria that can break down some of the compounds released by the plastic, according to Romera.which helps to reduce their impact on the ecosystem.
“Compounds released by plastic may be resistant to degradation and accumulate in the ocean, but we found that at least some of them could be used by bacteria,” said Marta Sebastián, also an ICM-CSIC researcher.
In fact, the research team now wants to explore this last aspect to see if marine bacteria can be used to ‘bioremediate’ or recover other plastic-contaminated environments.