Simulated sunlight reveals how 98% of plastics at sea go missing each year

Study explores removal mechanisms, microbial impacts and lifetimes of select microplastics on the ocean surface

Florida Atlantic University

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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.

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Co-authors of the study are Lixin Zhua, a Ph.D. student and lead author, East China Normal University; Thais B. Bittar, Ph.D.; and Aron Stubbins, Ph.D., both at Northeastern University; and Daoji Li, Ph.D., East China Normal University.

This work was supported by national key research and development program of China [2016YFC1402205], the United States National Science Foundation [1910621], The National Science Foundation of China [42676190, 41806137, 41676190), and a graduate fellowship from the Chinese Scholarship Council [201506140016].

About Harbor Branch Oceanographic Institute:

Founded in 1971, Harbor Branch Oceanographic Institute at Florida Atlantic University is a research community of marine scientists, engineers, educators and other professionals focused on Ocean Science for a Better World. The institute drives innovation in ocean engineering, at-sea operations, drug discovery and biotechnology from the oceans, coastal ecology and conservation, marine mammal research and conservation, aquaculture, ocean observing systems and marine education. For more information, visit http://www.fau.edu/hboi.

About Florida Atlantic University:

Florida Atlantic University, established in 1961, officially opened its doors in 1964 as the fifth public university in Florida. Today, the University, with an annual economic impact of $6.3 billion, serves more than 30,000 undergraduate and graduate students at sites throughout its six-county service region in southeast Florida. FAU’s world-class teaching and research faculty serves students through 10 colleges: the Dorothy F. Schmidt College of Arts and Letters, the College of Business, the College for Design and Social Inquiry, the College of Education, the College of Engineering and Computer Science, the Graduate College, the Harriet L. Wilkes Honors College, the Charles E. Schmidt College of Medicine, the Christine E. Lynn College of Nursing and the Charles E. Schmidt College of Science. FAU is ranked as a High Research Activity institution by the Carnegie Foundation for the Advancement of Teaching. The University is placing special focus on the rapid development of critical areas that form the basis of its strategic plan: Healthy aging, biotech, coastal and marine issues, neuroscience, regenerative medicine, informatics, lifespan and the environment. These areas provide opportunities for faculty and students to build upon FAU’s existing strengths in research and scholarship. For more information, visit fau.edu.

From EurekAlert!

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91 thoughts on “Simulated sunlight reveals how 98% of plastics at sea go missing each year

  1. No surprise to someone who lives in the tropics. We have to regularly replace plastic items like plastic clothes pegs, because they rapidly disintegrate under the influence of our harsh tropical sunlight.

      • It would be interesting to compare degradation rates of ocean plastics by sunlight vs. plastics disposed in landfills. Could it be an inconvenient fact that they go away faster in the ocean? Anyone w/ some data?? I know that PCBs (polychlorinated biphenys) weather and degrade when exposed to sunlight but hang around for a long long time when indoors or buried.

        • Was this study just about sunlight or did they also introduce microbes from the ocean that eat crude oil and plastics?

          • There have been bacteria discovered in landfills that have evolved to eat plastic. I believe they were first discovered about 15 years ago at a landfill in Japan.

    • What happens to the particles which sink and are no longer bombarded by solar radiation?
      Will future geologists demark our era with a definable sedimentation strata?

      A fair bit of plastic degradation is due to loss of VOCs (Volatile Organic Compounds) which evaporate from plastics. VOCs are all the compounds which make plastic flexible and supple. As they dissipate the plastic loses its plasticity and becomes brittle. You see the residue from these VOCs as it condenses and collects on the inside of the windshield a new car as hard to wipe off coating. Most of this dissipation is due to thermal exposure (IR) while the higher end of the spectrum (UV) is responsible for breaking the long polymer chains and further weakening the plastic.

      • It almost certainly gets eaten. There is no primary production below the photic zone, so all life in the deep ocean is dependent on the slow rain of organic material from above.

        There is virtually no organic material being deposited anywhere on the deep ocean floor at the present time – it is all eaten in short order.

        • Agreed. If you own a boat you have to put horribly toxic biocides into your fuel tank, otherwise the fuel tank fills up with fungus.

          Marine bacteria have no problem eating long chain hydrocarbons.

      • I moved from Southern CA to NV almost three years ago. I had kept large, folded plastic sheets (total 5000 ft sq) from my previous move (27 years ago) in the garage. When I went to move them, they practically exploded. I had tiny plastic shards no larger than 0.5 inch in length and width. Sweeping it up was like sweeping dust, as it continued to fracture.

        This was inside a closed garage – very little sunlight, none of it direct. Time and temperature had turned it extraordinarily hard and brittle. Temperatures ranged from 4 C to 44 C.

        Plastic doesn’t last forever, even without UV effects.

      • The plasticizers in use today are not usually VOCs per the legal definition of the US EPA. They are less volatile by design so that they will stay in the plastic for a long time. They still slowly evaporate, as you point out. I worked for a large chemical company that spent considerable money researching solvents that were less volatile than the legal standard so that they could be used with fewer restrictions. Solvents for paint was one area of research.

      • There are many many types of plastics – some lighter and some heavier (denser) than sea water which is ~1.026 +or-.

        Here’s a table w/ densities of over 170 plastics:

        https://omnexus.specialchem.com/polymer-properties/properties/density

        As the plastic particle size decreases due to degradation, the surface area-to-mass ratio goes up and the particles become easier for the bugs to degrade (biodegradation). The particles should also become more buoyantly neutral (think cloud aerosol vs. larger rain drops) so only the larger particles may sink.

      • Only PVC plastics often include plasticizers to make them more flexible. Think rigid PVC waste pipe vs. vinyl sheet material. Even then, those agents make=up only a modest fraction of the finished weight.

        Most of the packaging plastics (polyethylene, polypropylene, polyethylene terephthalate, polystyrene foam) do not need agents to render them flexible; particularly at the low sectional thickness of films and bottles. Most of these resins more typically need additives (calcium carbonate, glass fiber, etc.) as stiffeners (unlike PVC) when needed.

        Plastic resins can contain lubricants (for processing), UV/oxygen inhibitors and (for textiles) fire retardants, but that concentration of material seldom exceeds 1-2% of the total weights. Packaging materials are highly regulated due to food contact.

  2. And of course, as nano-particles, these nano-plastics will settle into our cells via eating them.
    OK, no worries, what could go wrong here?

    • So, if plastics breakdown to these nano-particles why wouldn’t the degradation continue to the elemental level? What is magical about a nano-particle that the breakdown would stop here?

    • One of my favorite beverages contains yeast pee. Yum. Mushrooms, grown in excrement. Yum. Lobsters who eat anything that settles to the bottom of the ocean. Yum. Farmers routinely spread animal excrement on their fields. Yum. The list is very very long.

      If you think about it the right way, most food is disgusting in one way or another. What could possibly go wrong? Lots … but it usually doesn’t.

      • Indeed. Chicken tastes the way it does because of bacteria. Blue cheese uses copper wire to promote the growth of mould. Penicillin was discovered from mould on bread.

      • there is also no known mechanism whereby solid particles get into the blood stream … they pass thru the human body … please don’t be so silly …

    • No, the nano plastics tend to go right through us. Marine birds have to be constantly fed plastic particles to keep the number constant. There are lots of nano-sized particles we eat every day that go right through us. No worries.

      • So that’s how Avogadro derived it; he fed marine birds and came up with 6.022 X 10²³. I wonder what he used, as plastics hadn’t yet been invented.

        Alright, “keep the number constant” means .. what?

    • They would not “settle into our cells”. It is borderline impossible to introduce something foreign into a cell and get it to stay there.

      • “And of course, as nano-particles, these nano-plastics will settle into our cells via eating them. OK, no worries, what could go wrong here?

        They would not “settle into our cells”. It is borderline impossible to introduce something foreign into a cell and get it to stay there.”

        Thanks for that I guess chemically inert means chemically inert. Presumably “foreign bodies” need a chemical interaction with the cell’s interior to ‘stick’.

  3. “polyethylene (33 years), and standard polyethylene (49 years),”

    I don’t know how to process these descriptions… LDPE? HDPE? Cross-linked PE?

  4. Another plastic removal mechanism is: crustaceans. Crustaceans like to stick on everything that is floating near the surface. The weight of their shells will make the plastic sink.

    After floating three years in the oceans near Taiwan, an underwater camera looks like this: https://nos.nl/data/image/2018/03/29/462779/2048×1152.jpg

    Source: https://nos.nl/artikel/2224956-camera-dobbert-bijna-drie-jaar-op-zee-en-komt-terug-bij-eigenaar.html (in Dutch)

    • And not just crustaceans. All kinds of things that live in the sea like algae will attach themselves to solid objects. I have ablative bottom paint on my boat for a reason. We pull our oyster floats attached to our dock once a month in the summer to power wash them to get rid of the slime on both the floats and the oysters.

      I will say however all the plastic in the oceans isn’t something we want and all the projects keeping it out and cleaning it up should be encouraged. And knowing how it breaks down could help in formulating plastic that will break down better if it does find it’s way into the water.

      • What the article (carefully) does not say is, What happens to the “nanoplastics”?
        The answer of course is, they are eaten by bacteria, etc. and broken down further as energy sources. That is why we see no very small particles – by that stage they are metabolised to CO2.
        That being said, plastic litter is unsightly and should be avoided.

  5. ‘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.’
    I suspect that mother nature will find a way to overcome that inhibition, she usually does.

    • “…may inhibit microbial activity.”
      Let me know when you have some real data. Until then, this is pure speculation and wringing of hands.

  6. The issue here is actually what they break down to and how much havoc those breakdown products might wreak before being fully degraded.

    Something breaking down does not stop it being a pollutant. It merely opens the door to asking whether it is or not and, if it is, what effects it may have.

    One of these decades, people will start assigning different compounds into ‘best used on earth’ and ‘better used in space, on planets lacking major life forms etc’.

    Until then ‘because we can’ will continue to trump ‘because it is appropriate on earth’….

  7. Leaving the oil in ground is best not floating or decaying in a fish whale whatevers that it kills by starvation pluging its stomach.science’s actors

    • Great! Now if we could only find a way to stop the natural seepage from ocean bottoms at a rate greater than our extraction therefrom …

    • Every day at Coal Oil Point (COP), the location of natural seeps off Santa Barbara, 20 to 25 tons of oil have leaked from the seafloor each day for the last several hundred thousand years.
      I suspect nature has learned how to deal with this issue, but you are welcome to protest, insisting that mother nature change her dirty ways.

  8. Why can we not see via satellite imagery the plastic patch in the Pacific the size of Texas? We can resolve objects the size of an aircraft door, but not a pact the size of Texas. Seems very odd to me.

  9. Einsteins equal and opposite reactions that produce light speed and infinite values are ignored by science to promote oil and nuclear energy by discrediting natural superiority sources. In his Kinetics .

  10. Let’s stop putting the stuff in the Oceans and get those along the major rivers in SE Asia to do likewise. Bury it in landfill or as artificial reefs in threatened coastal areas. Meanwhile I am off to collect the plastic nip bottles and flasks that some brainless individuals have strewn along the road in front of my house.

    • We should stop the recycling of plastics, (except for recyclers who seek out and pay for their raw material) and incinerate this, and other garbage to generate electricity, like they do in Sweden. Solves two problems in one fell swoop.
      It’s the “greens” who, by forcing recycling on normal people, have inadvertently caused this problem. Every “solution” the “greens” come up with to solve some non-problem, causes some other, real problem. Wind tubines are another example.
      Stop listening to them.

      • Timo, I agree. Incinerating municipal trash with proper air pollution controls is a win-win, producing electricity and greatly reducing land fill space. It might also provide financial incentive to collect combustible trash for cash instead of dumping it wherever (as into rivers and oceans). And of course the combustion will also provide CO2 plant food. What’s not to like?

        • Land fill are the worst way to depose of garbage, their leaching is well know yet no one will correct the mistake.

      • In Germany we are one step further. Landfills are prohibited. Plastic which is not recycled is burnt in Power Stations to generate electicity. The by-product heat is used to heat urban housings. We just should consider plastic as a sort of solid oil and use it for power production. Problem solved.

    • Oh but there’s a difference between a CO2 molecule from evil fossil fuel and one from naturally decaying biomass. The biomass has radioactive C14.
      /s

  11. As usual, the first two paragraphs are full of “could”, “may” and “might”. These words are speculation and have no place in a scientific report. If it “may” or “could” or “might”, do some work and find out if it does. Then, and only then, publish.

  12. Medical research biology labs use hepa-air filtered biocontainment hoods to do most of their cell biology work in. And molecular biology uses them as RNA work has to be done in a hood because RNAases are everywhere around us on every surface and in the air that is not UV sterilized. Any live cultures, and tissue culture (TC) work and most molecular biology has to be in hood, not just for containment, but to help keep your cultures from getting contaminated with bacteria and fungus, RNAases etc. The hoods have UV fluorescent tubes for sterilization. (The UV lamps I know have a harsher, shorter wavelength spectrum than solar UV at sea level)
    Usually one would pull the glass sash down on the hood at the end of the day, turn off the filter fanmotor, turn on the UV. Any plastics left in there after several weeks became brittle and disintegrated pretty easily. Some kinds faster than others. I can attest that polystyrenes got chewed up pretty quickly by UV. You certainly cannot leave expensive micropipetters in the hood on regular basis with using the UV sterilization at night without destroying them. But polystyrene has one advantage, it is heat resistant and most can be autoclaved, where polyethylene just melts in an autoclave.

    Biomedical labs are the worst for creating an enormous stream of plastic waste though. Most people would be shocked if they saw how much plastic waste is generated everyday in a busy research lab. Most of it is polystyrene, tissue culture stuff, TC trays, TC flasks. Adherent cell cultures don’t like polyethylene, the surface is too hydrophobic for adherence. Tubes come in all sizes from 0.5 mL to 50 mL capped tubes. And labs use tons of tubes. The tubes can be either polystyrene or polyethylene. But also lots and lots of polyethylene pipet tips. Literally thousands of small PE 1-time use tips, everyday just by 1 active researcher. Fortunately biohazard protocols had you bag all that waste into big red polyethylene biohazard bags, then put that in cardboard boxes, where it was collected by a biohazard waste service to be taken somewhere for incineration.

    My wife was always trying to cut down on our plastic recycle stuff at home, not buy plastic water bottles, and use glass and metal water refillable bottles instead, not get the plastic bags at the store, etc. A good ecowarrior. Then I would tell her how much plastic waste I just made that day, she’d be aghast. Of course none of the biowaste plastics are recycled, they are all burned somewhere. More shock and horror.

  13. The SOLUTION to garbage patches is simple. Pay all those out of work fishing boats to go out and fill their holds with plastic.

    Then you bring it to shore and dump it in a BIG pile on land.

    Ocean pollution problem SOLVED. The Democrat way.

    Fishing boat owners get government money. People feel good. And there is ANOTHER problem that needs solving by spending MORE government money.

  14. IT should be obvious to all by now. What we need are a few computer simulations of plastic ingress into the oceans, and the also obvious negative impact this has on natural climate balance.
    I once saw a guy using a hockey stick to bat plastic encapsulated scientific reports into the ocean. He was mumbling something like, the sea has eaten my global warming, it can now eat my unsold copies of “how to use statistics to fool idiots”
    I digress, I think twenty computer simulations running constantly then averaged, will tell us all we don’t need to know about false science… 🙂

  15. Plastic bottles are not made out of polyethylene nor polypropylene. Plastic bottles, including disposable water bottles and soda pop bottles, are made out of polyester, also known as polyethylene terephthalate. Re-usable water bottles, seen on every backpack these days, are made out of polycarbonate.

    What in the heck is “simulated sunlight” that lets polyethylene survive 49 years?

    This press release has too many errors to even be a bad translation, there is nothing true in this “study.” East China University, of course, world-renowned research facility.

  16. A step in the right direction. Nothing wrong with finding what happens to plastic in the ocean or anything else.
    My plastic spray can came apart in the back yard from sun and weather. A new saw I left in bushes for 1 year was covered with rust when found. I still have it. The point is nothing lasts for ever as some speak of plastic. Paint on cars fade in the sun and skin burns at the beach with salt or without.

    Finding how the breakdown happens can contribute to developing how to make products more resistant to the sun and plastic will last forever in the ocean as some say. I am confident scientists and manufacturers will know what to do with the information. Caution, keep it away from politicians. I don’t need a new Freon or smaller toilet tank.

  17. Plastics that interfere with wildlife I worry about, including in the ocean. However, between sunlight and bacteria, I have no worries about any plastics eventual disappearance from the ocean. Let us also not forget that in cleaning up plastic from the ocean surface we may destroy the habitats of surface dwelling creatures and decimate some rare creatures.

  18. I don’t see why polyethylene and the like could not be prepared with a trace (0.01% or perhaps less) of something like styrene or 2-naphthylethylene to produce a plastic with a covalent photosensitizer attached.

    Covalent attachment would make the additive non-toxic (it won’t leach out), and may greatly increase the rate of UV-photodegradation.

    Any polymer chemists out there to weigh in?

  19. We have cable running electricity from the house to the garage, this is covered in PVC and isn’t allowed under the latest rules here in the U.K. as it can break down in UV light.

  20. “ 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.”

    The layman’s translation of the above quote is,

    *Although our research found few, if any, problems from plastics in the ocean, perhaps if we keep looking we can find a problem. Therefore please continue funding our research.*

  21. I’m in need of a quick chemistry lesson. The propaganda sent home to my 6th grader identified most plastics as monomers rather than polymers.
    How are the two effected by sunlight differently?
    Also, were they correct?

    • Of course they are not correct. A monomer is the low-molecular-weight unit that polymerizes to make long chain hydrocarbons. For example, ethylene monomer polymerizes to polyethylene. There are NO plastics that are monomers, all are by definition polymers.

    • A monomer is a molecule capable of bonding into a longer chain of monomers, The chain of monomers is called a polymer (a monomer is to a polymer as a link is to a chain).

      When polymers break down, they break down into shorter polymers and individual monomers.

      Some one please correct me if I am wrong. My last chemistry class was in 1970.

      • You’re right, jtom, although polymers mostly do not break back down to the original monomers.

        The effect of UV light is two-fold.

        The direct effect is to break mostly Pol-C-H bonds into their radicals, Pol-C(dot) plus H(dot). The H(dot) diffuses away. The Pol-C(dot) part will react with almost anything that comes along, primarily O2 (N2 is inert. So is argon. CO2 could react with Pol-C(dot), though.)

        With O2, you get Pol-C-O-O(dot), which most readily attacks an adjoining Pol-C-H to make Pol-C-O-O-H plus a new Pol-C(dot).

        So a chain of reactions commences, producing a lot of Pol-C-O-O-H, which is chemically very reactive (related to peroxide) and will eventually break the polymer C-C bonds, producing smaller bits.

        The other way UV decomposes them is by direct production of ozone, O3. Ozone is extremely reactive, and will attack any nearby polymer (or anything else), and produce similar breakage reactions.

        Grammar school science teachers are often poorly trained. So, it’s not too surprising that one wouldn’t know the monomer/polymer dichotomy.

        Plastics often do include plasticizers, though, which are smallish hydrocarbons that are dissolved in the plastic itself, and make plastics pliable. Those can leach.

    • So if it’s such a HUGE problem, why did they make a cartoon instead of using actual pictures? With all those boats that were involved (belching out massive amounts of “carbon pollution” in the process) I’m sure someone on board had a camera. The reason they didn’t is because the whole “millions of fragments” amounted to a shoebox full of plastic. And it took TWO MONTHS OF DRAGGING and two years of sorting (hey, they say that themselves) to get that.

      Some desperate problem ya’ got there Pancho.

    • Unfortunately, in the US we have too many NORML (National Organisation for Reformation of Marijuana Laws) Universities.

  22. GREAT! This is terrific news!
    Don’t you see?
    Now we don’t have to worry about pollution-no need to recycle at all.
    Just dump it in the ocean and ***POOF***!
    All gone!
    YAY!

  23. Anecdotal evidence from a sugar cane farmer in Hawaii where polypipe used for irrigation is plowed in after harvest and replaced the following year. Fields should be full of spaghetti like tubing. However, reportedly, while last byear’s tubing remains, previous years’ tubing is either gone or substantially reduced.
    Would be a good PhD study.

  24. Why was the study done using artificial sunlight. Perhaps the “”Scientists””
    did not want to go outside and just enclose a part of the sea and let nature
    do what it does best.

    So we now know what to do with the rubbish, burn it to make electricity,
    or put it in enclosed sea water and let it rot away. I think that burning makes
    a lot more sense.

    MJE VK5ELL

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