TWH – Two recent reports about plastic pollution highlight both the challenges and the attempts at innovation to address the problems with plastics in the environment. While plastics are made from organic material, they do not readily return to the food chain of nature.
One report concerns a way to return one type of plastic to that food chain. The second report examines the post-use travels of plastic waste and suggests an individual-level intervention.
When exposed to light, plastics break down into small pieces through a process known as “photodegradation.” These small bits of plastic, known as microplastics, make up the majority of items found in the “Great Pacific Garbage Patch,” where they float suspended in the water column. Image credit: NOAA Marine Debris Program – Public Domain
Recycling plastic waste fails to be cost-effective
Recycling plastic waste fails to transform waste into either a usable raw material or a usable part of the food chain. Separating the different types of plastic is labor-intensive. Unlike labor-intensive separation, processing plastic waste uses toxic solvents as well as a great deal of energy. Products made from recycled plastic tend to fail quality checks.
Possible breakthrough
Berkeley News reported a breakthrough in the development of bio-degradable plastics.
Manufacturers market as “compostable” a type of plastic, made up of polylactic acid (PLA). Typical composting, however, fails to return those plastics to the food chain. Non-compostable, they can contaminate other recyclable plastics.
Ting Xu and other researchers at the University of California, Berkeley have developed a new way to break down PLA. In a few weeks, that process, using heat and water, returns the PLA to the food chain.
The new process embeds polyester-eating enzymes into the plastic during manufacture, which are enveloped by a polymer. When exposed to heat and water, the single-polymer envelope dissolves. This allows the enzymes to begin to eat the PLA and transform it into lactic acid. Soil microbes then consume the lactic acid, effectively returning the PLA to the food chain.
This enzyme action occurs during both industrial and municipal composting. The latter can take 60 to 90 days, while the former occurs more rapidly.
Plastic made with this process fails to break down at lower temperatures or in brief periods of damp. Polyester shirts made using this process can withstand sweating and washing.
The US Army Research Office supported this program. The Army wanted to improve Army logistics and waste management. At present, no one knows if this process will work economically.
Where plastic waste travels post-use
Vox.com has produced a YouTube video exploring how plastic travels after its use.
The five oceanic garbage patches would be a likely destination for plastic garbage. One patch, the Great Pacific Garbage Patch (GPGP), lies between California and Hawaii and is twice the size of Texas. A second patch lies off the coast of Chile, a third patch floats between the Caribbean and northwestern Africa. The fourth lies between southern Brazil and southern Africa, and the fifth is in the Indian Ocean between Madagascar and Australia.
Storms push loose material on the ground into streams and rivers. Those rivers carry material into the oceans. Wind and ocean currents drive loose material to the five oceanic garbage patches.
These garbage patches look like a cloudy soup. Ranging from large to microscopic, plastic items float therein. People first noticed these patches in the 1990s. At first, people assumed that almost all plastic waste ended up there.
Recent research has largely challenged that assumption. Scientists estimated the total volume of plastics on GPGP’s surface to be a few hundred thousand tons. While that sounds like a lot, it represents only 1% of the estimated eight million tons of plastic going into the oceans each year.
This raises the question, where does the rest of the plastic waste go?
Some plastic ends up on the seafloor. Scientists examined sediments from the seafloor of the Santa Barbara Basin, which lies off the coast of southern California. In these sediments, scientists found microplastic plastic fibers or fragments measuring one mm or less. Like tree-ring analysis, these sediments record segments of time.
Plastic production dramatically increased after 1945. In every year after 1945, the amount of microplastics in the sediment has increased. Every 15 years thereafter, the amount doubled, a pattern that parallels global plastic production.
Microplastics found in the ocean – Image credit: Oregon State University – CC BY-SA 2.0
Some microplastics came from synthetic clothing breaking down, other microplastics resulted from larger plastic items disintegrating. In addition to microplastics being found on the seafloor, they are also found in the digestive system of sea creatures.
Research in the Arctic Ocean found that large plastic objects sometimes sink to the seafloor, relatively intact. About 50% of plastics have greater density than seawater, making them likely to sink. Barnacles and mussels sometimes attach themselves to plastic items floating on the surface. Eventually, these plastic items will grow heavy enough to sink.
This would suggest that the plastic items remaining on the surface of these oceanic garbage patches would be more recent. Examination of plastics floating in the GPGP found them to be older. Which raises an interesting question: “Where are all the newer plastics?”
Those newer plastics lay close to the coastline, near where people had left them. Scientists have found that plastic debris on the coastline tends to be younger.
According to computer modeler Erik van Sebille, more recent plastic waste ends up in a 100-mile zone at the coastline. Storms, wave action, and wind move plastic waste between shoreline, ocean surface, ocean floor, another part of the shoreline, and back again. All that churning, movement causes friction and results in the plastic breaking up, into smaller and smaller pieces. Eventually, those pieces will find their way into the oceanic plastic garbage patches.
What can be done?
On an individual level, people can choose to avoid buying or using plastic material, a practice known as “precycling,” which can include buying unpackaged, reusable, or recyclable products, and using their own reusable bags for shopping. Unfortunately, this practice is not always possible.
Another option is for individuals or groups to devote energy to cleaning up the coastal zone where newer plastic waste is concentrated. While a feasible notion, the world has 400,000 miles of coastline and not everyone lives in close proximity to a coastline.
Individual-level responsibility can certainly result in some reduction in plastic waste, but not everyone will engage in this level of action. The major impact on reducing the amount of plastic pollution will likely require concerted action that occurs on global social, economic, and political levels. Still, individual actions like picking up plastics anytime they are encountered in nature or organizing cleanups can have a major impact.
To learn more about plastic pollution in the oceans: visit PlankOnDrift, an interactive website that shows where plastic originated before it began to sink, and Ocean Parcels a project developed and used by researchers to track how ocean currents transport plastics and other materials, you can also find them on Twitter.
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