Like India?
Posted on 11/08/2019 8:00:33 AM PST by LesbianThespianGymnasticMidget
Study explores removal mechanisms, microbial impacts and lifetimes of select microplastics on the ocean surface
Florida Atlantic University
216184_web
A schematic figure of plastic photo-dissolution and plastic dissolved organic carbon (DOC) biodegradation. Credit: Lee Ann DeLeo
Trillions of plastic fragments are afloat at sea, which cause large “garbage patches” to form in rotating ocean currents called subtropical gyres. As a result, impacts on ocean life are increasing and affecting organisms from large mammals to bacteria at the base of the ocean food web. Despite this immense accumulation of plastics at sea, it only accounts for 1 to 2 percent of plastic debris inputs to the ocean. The fate of this missing plastic and its impact on marine life remains largely unknown.
It appears that sunlight-driven photoreactions could be an important sink of buoyant plastics at sea. Sunlight also may have a role in reducing plastics to sizes below those captured by oceanic studies. This theory could partly explain how more than 98 percent of the plastics entering the oceans go missing every year. However, direct, experimental evidence for the photochemical degradation of marine plastics remains rare.
A team of scientists from Florida Atlantic University’s Harbor Branch Oceanographic Institute, East China Normal University and Northeastern University conducted a unique study to help elucidate the mystery of missing plastic fragments at sea. Their work provides novel insight regarding the removal mechanisms and potential lifetimes of a select few microplastics.
For the study, published in the Journal of Hazardous Materials, researchers selected plastic polymers prevalently found on the ocean surface and irradiated them using a solar simulator system. The samples were irradiated under simulated sunlight for approximately two months to capture the kinetics of plastic dissolution. Twenty-four hours was the equivalent of about one solar day of photochemical exposure in the subtropical ocean gyre surface waters. To assess the physical and chemical photodegradation of these plastics, researchers used optical microscopy, electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy.
Results showed that simulated sunlight increased the amount of dissolved carbon in the water and made those tiny plastic particles tinier. It also fragmented, oxidized and altered the color of the irradiated polymers. Rates of removal depended upon polymer chemistry. Engineered polymer solutions (recycled plastics) degraded more rapidly than polypropylene (e.g. consumer packaging) and polyethylene (e.g. plastic bags, plastic films, and containers including bottles), which were the most photo-resistant polymers studied.
Based on the linear extrapolation of plastic mass loss, engineered polymer solutions (2.7 years) and the North Pacific Gyre (2.8 years) samples had the shortest lifetimes, followed by polypropylene (4.3 years), polyethylene (33 years), and standard polyethylene (49 years), used for crates, trays, bottles for milk and fruit juices, and caps for food packaging.
“For the most photoreactive microplastics such as expanded polystyrene and polypropylene, sunlight may rapidly remove these polymers from ocean waters. Other, less photodegradable microplastics such as polyethylene, may take decades to centuries to degrade even if they remain at the sea surface,” said Shiye Zhao, Ph.D., senior author and a post-doc researcher working in the laboratory of Tracy Mincer, Ph.D., an assistant professor of biology/biogeochemistry at FAU’s Harbor Branch and Harriet L. Wilkes Honors College. “In addition, as these plastics dissolve at sea, they release biologically active organic compounds, which are measured as total dissolved organic carbon, a major byproduct of sunlight-driven plastic photodegradation.”
Zhao and collaborators also checked the biolability of plastic-derived dissolved organic carbon upon marine microbes. These dissolved organics seem to be broadly biodegradable and a drop in the ocean compared to natural biolabile marine dissolved organic carbon. However, some of these organics or their co-leachates may inhibit microbial activity. The dissolved organic carbon released as most plastics photodegraded was readily utilized by marine bacteria.
“The potential that plastics are releasing bio-inhibitory compounds during photodegradation in the ocean could impact microbial community productivity and structure, with unknown consequences for the biogeochemistry and ecology of the ocean,” said Zhao. “One of four polymers in our study had a negative effect on bacteria. More work is needed to determine whether the release of bioinhibitory compounds from photodegrading plastics is a common or rare phenomenon.”
Samples in the study included post-consumer microplastics from recycled plastics like a shampoo bottle and a disposable lunch box (polyethylene, polypropylene, and expanded polystyrene), as well as standard polyethylene, and plastic-fragments collected from the surface waters of the North Pacific Gyre. A total of 480 cleaned pieces of each polymer type were randomly selected, weighed and divided into two groups.
“The potential that plastics are releasing bio-inhibitory compounds during photodegradation in the ocean could impact microbial community productivity and structure, with unknown consequences for the biogeochemistry and ecology of the ocean,”
They want funding next year.
Net/net of the article: The sun breaks down plastics in the ocean and what is released is bio-available, ie food for stuff.
Net/net of the article: The sun breaks down plastics in the ocean and what is released is bio-available, ie food for stuff.
Couldn’t plastic be degraded into harmless chemicals, in treatment plants, before it is dumped into the oceans, just as human waste is rendered harmless?
we need to dump more stuff into the oceans...
Sure, but that would take energy to feed the reactions, and money to collect, sort, and transport all the plastic. Plus I think most of the plastic ending up on the ocean is not being dumped in the ocean intentionally by responsible parties who care about the environment.
A simpler solution is just to burn plastic and use the heat from that to generate electricity to offset the costs of collecting it. Fat chance the green crowd would let us do that though.
It’s our best chance to stop Cthulhu from rising again!
95% or some ridiculous amount of plastic ocean waste dumps out of the Yellow and Yangtze Rivers and the Ganges. China and India respectively with almost all the rest dumped out of Africa. The civilized world does not dump plastic in the oceans.
Get those places to clean up their acts and problem solved.
It is not rocket surgery nor brain science. It is them. No need to treat our plastics. We don’t dump them.
Net/net of the article: The sun breaks down plastics in the ocean and what is released is bio-available, ie food for stuff.
***********************************************************************
This is stunning and so unexpected considering that plastics are made from organic material. /sarc
In a somewhat related phenomenon:
“Vehicles may crowd the asphalt of downtown Los Angeles freeways above ground, but below ground hundreds of newly discovered bacteria thrive by munching on heavy oil and natural asphalt. Trapped in the Rancho La Brea tar pits 28,000 years ago, the bacteria are equipped with special enzymes that can break down petroleum”
Source: https://www.livescience.com/1515-asphalt-munching-bacteria-discovered.html
Life on Earth is relentless.
Like India?
See #7
Your point is exceedingly valid.
Pic is a reminder of how fortunate we are to live where we do
Hey, cut India some slack. That is progress from the feces and human corpses that used to fill that waterway!
/ simulated sunlight increased the amount of dissolved carbon in the water /
Hmmmm, doesn’t take a thermodynamics physicist to extrapolate this to “Climate Change” resolution.
It’s racist to accuse India and China. Why? Just ‘cause it is.
Stupid-Useless-Paper-Straws BUMP
Enter George Carlin:
The earth doesn’t share our prejudice towards plastic.....
“The planet … is a self-correcting system. The air and the water will recover, the earth will be renewed. And if it’s true that plastic is not degradable, well, the planet will simply incorporate plastic into a new paradigm: the earth plus plastic. The earth doesn’t share our prejudice toward plastic. Plastic came out of the earth. The earth probably sees plastic as just another one of its children. Could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn’t know how to make it. Needed us. Could be the answer to our age-old egocentric philosophical question, ‘Why are we here?’”
“Plastic...A-Hole!”
-George Carlin
95% of river-borne plastic polluting the world's oceans comes from just TEN rivers
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.