The Plastic Catastrophe in the Ocean Is Even Worse Than We Thought
New research shows that the plastic problem is growing,
but the full impact on marine life remains unknown.
By Taylor Hill / TakePart
December 17, 2015
Somewhere between 15 trillion and 51 trillions pieces of plastic litters the world’s oceans, a new study has found. That’s three to 10 times more plastic than scientists had previously estimated.
The study, led by climate scientist Erik van Sebille at London’s Imperial College and coauthored by researchers at nonprofit group 5 Gyres, built on the findings of two papers published last year. The scientists tapped every data set on plastic pollution published since the 1970s and ran the numbers through three computer models
The total weight of small plastic pieces that accumulated in 2014 alone is estimated to be between 93,000 and 236,000 metric tons, “which is only approximately one percent of global plastic waste estimated to enter the ocean” annually, the researchers wrote. The study only focused on microplastics (those less than 200 millimeters in size) that could be captured by trawling nets pulled along the ocean surface. Thus the researchers’ estimates do not count plastic waste that ends up sinking to the ocean floor or is ingested by fish and other marine species.
Each American throws away as much as 185 pounds of plastic a year. In the last decade, the total weight of plastic products entering the market has risen from 225 million tons in 2004 to 311 million tons in 2014, according to industry group association Plastics Europe.
“These estimates are larger than previous global estimates, but vary widely because the scarcity of data in most of the world ocean,” the researchers wrote. Studies estimate that large amounts of plastic go undetected because they sink to the ocean floor or are eaten by fish.
In one study, deep-sea fish in the North Pacific gyre were estimated to have ingested between 12,000 and 24,000 metric tons of microplastics annually.
According to the new study, the wide range in the estimated amount of plastic entering the world’s oceans every year “reveals a fundamental gap in understanding.”
But the data available shows that the North Pacific Ocean, often referred to as the “Great Pacific Garbage Patch,” has the highest density of plastic thanks in part to the region’s circular ocean currents and wind patterns.
This article originally appeared on TakePart.com. Reprinted with permission
How long does it take for plastics to biodegrade?
by William Harris
Drop a ketchup bottle on the floor, and you'll be thankful for polyethylene terephthalate, or PET, the nearly indestructible plastic used to make most containers and bottles. Drop the same bottle into a landfill, however, and you might have second thoughts. Why? Because petroleum-based plastics like PET don't decompose the same way organic material does. Wood, grass and food scraps undergo a process known as biodegradation when they're buried, which is a fancy way of saying they're transformed by bacteria in the soil into other useful compounds. But bacteria turn up their noses at plastic. Load their dinner plates with some plastic bags and bottles, and the one-celled gluttons will skip the meal entirely. Based on this logic, it's safe to argue that plastic will never biodegrade. Of course, that's not the end of the story. It was recently demonstrated that certain types of bacteria can break down plastic.
Until waste treatment plants can implement any new processes, however, the only real way to break down plastic is through photodegradation. This kind of decomposition requires sunlight, not bacteria. When UV rays strike plastic, they break the bonds holding the long molecular chain together. Over time, this can turn a big piece of plastic into lots of little pieces.
Of course, plastic buried in a landfill rarely sees the light of day. But in the ocean, which is where a lot of discarded grocery bags, soft drink bottles and six-pack rings end up, plastic is bathed in as much light as water. In 2009, researchers from Nihon University in Chiba, Japan, found that plastic in warm ocean water can degrade in as little as a year. This doesn't sound so bad until you realize those small bits of plastic are toxic chemicals such as bisphenol A (BPA) and PS oligomer. These end up in the guts of animals or wash up on shorelines, where humans are most likely to come into direct contact with the toxins.
One solution to this environmental disaster is biodegradable plastic. There are two types currently on the market -- plant-based hydro-biodegradable plastic and petroleum-based oxo-biodegradable plastic. In the former category, polylactic acid (PLA), a plastic made from corn, tops the list as the most talked-about alternative. PLA decomposes into water and carbon dioxide in 47 to 90 days -- four times faster than a PET-based bag floating in the ocean. But conditions have to be just right to achieve these kinds of results. PLA breaks down most efficiently in commercial composting facilities at high temperatures. When buried in a landfill, a plastic bag made from corn may remain intact just as long as a plastic bag made from oil or natural gas.