PLASTIC IN THE OCEANS
“Biodegradable Plastics: A Proven Solution to the Problem of Marine Plastic Waste”
A research team at Tokyo University has confirmed the biodegradation of biodegradable plastics in harsh deep-sea environments. They say:
Biodegradable plastics are receiving increasing attention. Conventional plastic, used for the parts, packaging, and containers of various products, is known to end up in the sea only to never decompose. There, it causes adverse effects on the environment. This has sparked the rising importance of transitioning to biodegradable plastics that can be broken down by microorganisms.
Plastic production for use in products in all industries is reported to be approximately 400 million tons worldwide each year. Reports also show that every year, about 8 million tons are thrown away and end up in the ocean. The great majority are plastics synthesized from petroleum that microorganisms cannot break down.
Plastic shopping bags, food containers, and bottles used by consumers generate massive amounts of waste. Some remain outdoors due to littering or inadequate collection and eventually end up in rivers and flow into the sea.
However, the deep sea, where marine plastic waste ends up, is a harsh low-temperature environment with little nutrient. Does this mean that the microorganisms essential for decomposition may be very scarce? What is the reality? A team including researchers from the University of Tokyo is working to confirm the real situation for plastics in the deep sea.
As these plastics drift in the ocean, UV radiation and waves break them into microplastics, or pieces smaller than 5 millimeters. They gradually sink and eventually reach the deep ocean floor. Some microplastics are small enough to be invisible to the naked eye, but they retain their plastic properties and do not chemically decompose.
Recently, strong calls for a transition to biodegradable plastics are on the rise. Biodegradable plastics can be completely broken down by microbial activity into CO2 and water. They could greatly reduce the burden on the environment.
But will switching to biodegradable plastic work? The final destination of marine plastic waste is the deep sea. With an absence of sunlight, water temperatures between 2 to 4 degrees Celsius, and very few nutrients, it is a harsh environment for biological activity..
Until recently, no one had confirmed the existence of microorganisms in the deep sea that can decompose plastic. A team of researchers from the University of Tokyo, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and the National Institute of Advanced Industrial Science and Technology (AIST) embarked on a mission to verify the situation.
The team placed samples of several types of biodegradable plastics at five different deep-sea locations with varying depths and environments. “The samples were retrieved between 3 to 14 months later. Upon examination, except polylactic acid (PLA) plastic, which decomposes only in high-temperature and high-humidity environments, the plastic samples had all undergone changes. “
This discovery marks the first time these microorganisms’ ability to break down plastic has been confirmed. Also, they are known to exist in seabed sediments worldwide. Accordingly, the team concluded that biodegradable plastics would be decomposed in deep-sea environments around the world – even at marine plastic waste’s final destination – the deep seabed.
According to the team’s calculations, a biodegradable plastic shopping bag will decompose in approximately 3 weeks to 2 months off Hatsushima at a depth of 855 meters.
This study reinforces the studies already done in the marine environment, the most important of which is the four-year Oxomar study sponsored by the French National Agency for Research which “clearly shows that biodegradable plastics biodegrade in seawater and do so with a significantly higher efficiency than conventional plastics. The oxidation level obtained due to the d2w prodegradant catalyst was found to be of crucial importance in the degradation process.”
According to Professor Tadahisa Iwata of the University of Tokyo “To mitigate future marine plastic pollution, we must use biodegradable plastics in products where leakage into the marine environment is unavoidable.”
Michael Stephen
Michael Stephen is a lawyer and was a member of the United Kingdom Parliament, where he served on the Environment Select Committee. When he left Parliament Symphony Environmental Technologies Plc. attracted his attention because of his interest in the environment. He is now Deputy Chairman of Symphony, which is listed on the AIM market of the London Stock Exchange, and is the founder and Chairman of the Biodegradable Plastics Association.
Earlier Postings in this Column
All articles from Michael Stephen
Interview with Michael Stephen
Questions and Answers on OXO-Biodegradability
Disclaimer
The opinions expressed here by Michael Stephen and other columnists are their own, not those of Bioplasticsnews.com