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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Not so biodegradable: Bio-based plastic and plastic-blend textiles do   
   not biodegrade in the ocean    
    Experiment off Scripps Pier finds only natural fibers degrade in the   
   marine environment; plastic fabrics remain intact one year later    
      
     Date:   
         May 24, 2023   
     Source:   
         University of California - San Diego   
     Summary:   
         A new study tracked the ability of natural, synthetic, and blended   
         fabrics to biodegrade directly in the ocean.   
      
      
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   FULL STORY   
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   Plastic pollution is seemingly omnipresent in society, and while   
   plastic bags, cups, and bottles may first come to mind, plastics are   
   also increasingly used to make clothing, rugs, and other textiles.   
      
   A new study from UC San Diego's Scripps Institution of Oceanography,   
   published May 24 in the journal PLOS One, for the first time tracked   
   the ability of natural, synthetic, and blended fabrics to biodegrade   
   directly in the ocean.   
      
   Lead author Sarah-Jeanne Royer conducted an experiment off the Ellen   
   Browning Scripps Memorial Pier and found that natural and wood-based   
   cellulose fabrics degraded within a month. Synthetic textiles, including   
   so-called compostable plastic materials like polylactic acid (PLA), and   
   the synthetic portions of textile blends, showed no signs of degradation   
   even after more than a year submerged in the ocean.   
      
   "This study shows the need for standardizing tests to see if materials   
   promoted as compostable or biodegradable actually do biodegrade   
   in a natural environment," said Royer, who performed the research   
   while a postdoctoral scholar in the Dimitri Deheyn laboratory at   
   Scripps Oceanography. Royer currently remains affiliated with Scripps   
   Oceanography as a visiting scholar from Hawaii Pacific University. "What   
   might biodegrade in an industrial setting does not necessarily biodegrade   
   in the natural environment and can end up as marine and environmental   
   pollutants."  Startling images of landfills stacked with mountains of   
   thrown away clothing in Chile and Kenya show the global ramifications of   
   fast fashion. An estimated 62 percent of textiles -- 68 million tons --   
   are now made from plastic fibers and plastic blends, which can persist   
   in the environment for decades to centuries.   
      
   Synthetic textiles also create plastic pollution from microfibers   
   shedding during regular wearing and washing. Most washing machines are   
   not designed to filter for microfibers, that then end up in wastewater,   
   and ultimately the ocean.   
      
   Bio-based plastics made from renewable natural resources such as   
   cornstarch or sugar cane have been marketed as a potential solution to   
   the plastic problem.   
      
   PLA is one such polymer in the bio-based plastics market, often labeled   
   as biodegradable and compostable. The team chose this textile for the   
   study given its extensive use as a replacement for oil-based materials.   
      
   For the experiment, ten different types of fabrics were used including   
   wood- based cellulose (known commercially as Lyocell, Modal, and Viscose);   
   natural cellulose (organic virgin cotton and non-organic virgin cotton);   
   bio-based plastic (PLA); oil-based plastic (polyethylene terephthalate   
   and polypropylene), and fabric blends of Lyocell mixed with polyester   
   and polypropylene. All these are commonly used in the textile industry.   
      
   Polyethylene terephthalate is a type of polyester often marketed as a   
   recycled textile. Polypropylene is used in textiles, carpets, geotextiles,   
   packaging materials, and disposable medical textiles such as masks.   
      
   The textile samples were placed in flow-through containers deployed   
   both at the sea surface and at the seafloor approximately 10 meters (32   
   feet) deep. Samples were examined every seven days with images taken,   
   and small pieces removed from duplicate samples for further examination   
   in the lab. This included scanning electron microscopy to examine the   
   fibers at high resolution, and Raman spectroscopy to gain information   
   about the chemical composition and molecular structure of the fibers. The   
   samples were then submerged again, in a process that lasted for 231 days   
   at the sea surface and 196 days at the seafloor.   
      
   After the conclusion of the Scripps Pier experiment, the samples were   
   moved to the Experimental Aquarium at Scripps Oceanography, where samples   
   were exposed to controlled conditions of flowing seawater. While the   
   natural, cellulose- based textiles repeatedly disintegrated in 30-35 days,   
   the oil-based and bio- based materials showed no sign of disintegration   
   even after a total of 428 days.   
      
   "The natural, cellulose-based materials would disintegrate in about   
   one month, so we would exchange for a new sample after the old one   
   disintegrated," said Royer. "The natural samples were replicated five   
   times, while the plastic samples remained the same for more than a year."   
   Examining the samples via electron microscopy allowed Scripps marine   
   biologist Dimitri Deheyn, senior author of the study, to measure the size   
   and structure of each fiber. The natural fibers became thinner with time,   
   while the diameter of the plastic fibers remained the same showing no   
   sign of biodegradation.   
      
   Study co-author Francesco Greco performed the Raman spectroscopy   
   analysis at the Department of Geology of Northwest University, China,   
   looking at the structural-chemical degradation of the fibers. Greco,   
   now at the Weizmann Institute of Science, found significant changes in   
   the chemical fingerprint of the cellulose-based materials, while bio-   
   and oil-based plastics remained unchanged.   
      
   Fiber blends, which interweave natural fiber strands with bio- or   
   oil-based plastic strands, are often promoted as a more sustainable   
   alternative to textiles made entirely from synthetic plastics. This   
   study showed, however, that only the natural part of the fiber degraded,   
   with the plastic portion of the blend remaining intact.   
      
   Additionally, the same type of fabrics were tested in a closed-system   
   bioreactor by an independent company, which replicates a marine   
   environment in an enclosed, indoor system. The bioreactor allowed   
   measurements of the percent of carbon dioxide produced by microbial   
   activity using the fabrics as nutrients, which was thus used as a proxy   
   for measuring biodegradability. The cellulose-based materials showed   
   complete biodegradation within 28 days, whereas the oil-based and   
   bio-based fibers did not show any sign of biodegradation.   
      
   Study authors note that the bio-based polylactic plastic, marketed as   
   an ecologically promising material, and the oil-based polyethylene   
   terephthalate and polypropylene, represent an important source of   
   human-caused pollution, and the fate of how these materials act in a   
   natural environment should be further explored.   
      
   "This comparative study highlights how crucial our language is around   
   plastics," said Deheyn. "Indeed, a bioplastic like PLA, commonly assumed   
   to be biodegradable in the environment because it contains the prefix   
   'bio,' is actually nothing like that."  Given these results, Royer and   
   the team hope consumers will become more aware of the power of their   
   own choices "Consumers who are concerned about microfiber plastic   
   pollution should be mindful of the materials they are buying," said   
   Royer. "We should all aim to buy fewer garments, opt for high-quality,   
   cellulose-based materials like cotton, merino or wool that will last   
   longer, or look to more circular and sustainable options that repurpose   
   items like clothing swaps and Buy Nothing groups."  The study was funded   
   by the Biomimicry for Emerging Science and Technology (BEST) Initiative   
   from the Deheyn lab with contributions from Lenzing, The Walter Munk   
   Foundation for the Oceans, and Preserve Calavera. The Raman analysis   
   was supported by the Young Thousand Talents Plan of China.   
      
   In addition to Royer, Deheyn and Greco, Michaela Kogler from Lenzing is   
   a co- author of the study.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Environmental_Awareness # Pollution #   
                   Oceanography # Oil_Spills # Environmental_Issues #   
                   Energy_and_the_Environment # Ecology # Air_Quality   
       * RELATED_TERMS   
             o Rogue_wave_(oceanography) o Ocean_current o Ocean o Coast   
             o El_Nin~o-Southern_Oscillation o Oceanic_trench o River o   
             Global_climate_model   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_San_Diego. Original written by Lauren Fimbres   
   Wood. Note: Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Sarah-Jeanne Royer, Francesco Greco, Michaela Kogler, Dimitri   
      D. Deheyn.   
      
         Not so biodegradable: Polylactic acid and cellulose/plastic blend   
         textiles lack fast biodegradation in marine waters. PLOS ONE,   
         2023; 18 (5): e0284681 DOI: 10.1371/journal.pone.0284681   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230524181813.htm   
      
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