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Fate of Plastics in Oceans

Plastics in the Oceans : A technical perspective. Fate of Plastics in Oceans. Tony Andrady September, 2005. Tony L. Andrady PhD Research Triangle Institute Durham, NC 27709. RTI International , Research Triangle Park, North Carolina 27709. Plastics and the Future.

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Fate of Plastics in Oceans

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  1. Plastics in the Oceans: A technical perspective Fate of Plastics in Oceans Tony Andrady September, 2005 Tony L. Andrady PhD Research Triangle Institute Durham, NC 27709 RTI International, Research Triangle Park, North Carolina 27709

  2. Plastics and the Future • The growth rate of plastics in the US has been phenomenal! [115 billion pounds in 2004] • As a material plastics offer some unique advantages in numerous applications including marine applications. • Global population trends and economic considerations predict that plastics production and use will increase in the future. This will invariably create an increasing amount of plastics waste. • The challenge is to minimize the component of that waste that ends up in the oceans.

  3. Specific Gravity of Plastics Density of Sea Water {T, Salinity, pressure} ~ 1.025 Negatively buoyant plastic materials impact the benthic environments and generally are not encountered in beach clean-up or surface water counts.

  4. Breakdown of Plastics in Oceans • UV radiation in sunlight[290-400 nm] • Slow thermal oxidation • Hydrolysis (degradation by water) • Biodegradation Breakdown and disintegration of plastics floating in the marine environment is very much slower than that exposed on land.

  5. ASTM D5437-93 Exposure Method

  6. Extensibility of Polypropylene Tape lo l

  7. Reasons for Retardation • Lower sample temperatures • No chance of heat build-up in sample • Lower temperature = much slower oxidation • Also, negatively buoyant material gets no UV at all • Biofouling of Sample Surface • Sample surface covered by foulants • Effective shielding from UV radiation 12 22 33 C

  8. Extensibility as a Measure Percent Change in Extensibility

  9. Molecular Weight at Embrittlement Enhanced photodegradable polyethylene in Miami (FL) • Embritlled plastics avoid entanglement • The particles can still be ingested • Possible ingestion-related distress to lower organisms • Residual particles are still polymeric. No mineralization has occurred. The material does not participate in the carbon cycle

  10. Photodegradable Six-pack Rings

  11. Enhanced Photodegradation POLYETHYLENE PHOTODEGRADABLE Low molecular weight residue

  12. Microplastics Debris • What is known about how plastics degrade in the environment stronglysuggest that microplastics would be a product of disintegration. • Microplastics (~20 microns in diameter) observed both in the sediment (Thompson, 2004) and in surface waters (Moore, 2003) • What is the impact of microplastics on filter feeders and the zooplankton population? • 99 percent of marine species are benthic. What is the impact of microplastics on these? • What is the role of microplastics in transferring invasive species within the marine environment [Murray, 2000]

  13. Zooplanktons and Plastic Particles Euphasia pacifica • Particle size can be small enough to be ingested • Will they ingest polyethylene?

  14. Polyethylene in Zooplankton Plastic Particles in gut Plastic in Fecal Pellet 1. Polyethylene particles of average particle size of 20 microns 2. Freshly caught zooplankton sample tested in a container Pictures courtesy Professor A. Aldredge (Santa Barbara)

  15. What we know…. • Plastics degradation at sea is almost exclusively via photodegradation and occurs much slower compared to that on land. • Embrittled plastics products present little or no entanglement/ ingestion threat to higher marine animals. • The disintegration sequence of plastics in the ocean generates plastics microparticles • Microparticles concentrate organic compounds (including toxic compounds) present in sea water • These microparticles can be readily ingested by some zooplanktons.

  16. What we do not know…. • Is there any serious impact due to ingestion of bioinert plastics? • Will they ingest microplastics laden with concentrated chemicals? - Natural safety mechanisms exist for krill Pseudo-nitzschia sp (diatom in toxic and non-toxic forms) Krill fed on toxic diatoms stop feeding for awhile • Are the chemicals bioavailable to zooplankton? Are there ecosystem level consequences? • Can the chemical species flow up the food pyramid to human consumers? Domoic acid

  17. Thank You for Caring! We did not inherit this earth and its oceans from our forefathers. We have merely borrowed it from our children

  18. Thank You for Caring! We did not inherit this earth and its oceans from our forefathers. We have merely borrowed it from our children

  19. Cassin’s Aucklet – DA transfer pathway Need to consume 67% of body mass/day of krill Translates into 31 µg/g of toxin in bird tissue Chicks ~ 40g of food (adult 120 g/day) ~10 31 µg/g FDA limit is 20 31 µg/g animal tissue for humans. (Ptychoramphus aleuticus )

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