Lecture 15 Flashcards
(35 cards)
where are plastics derived from?
mostly fossil fuel-based chemicals like natural gas or petroleum, however some recent methods use variants made from renewable materials such as corn or cotton derivatives
what is plastic?
- thousands of formulations
- can cause acute or chronic toxicity
- does not break down chemically
- its very nature makes it difficult to study, understand and regulate
how much plastic produced is packaging and single use?
36%
what is the fate of plastic waste?
1) recycled or reprocessed into a secondary material
- this delays rather than avoids final disposal
- reduces future plastic waste generation only if it displaces primary production
- mixing of polymer types generate secondary plastics of limited or low technical and economic value
2) plastics can be destroyed thermally
- most is by incineration without energy recovery
- can cause environmental and health impacts
3) plastics can be discarded and either contained in a managed system, such as landfills, or left uncontained in open dumps or in the natural environment
where are most plastics discarded?
around 60% are discarded and accumulate in landfills or in the natural environment
how much of Canada and USA’s plastic are recycled?
less than 9%
why are macroplastics a concern for marine mammals?
- charismatic species have been visible victims of nets and other debris for decades
- packing bands, fishing gear, and plastic bags entangle turtles, seabirds, and marine mammals
- lost items, ghost gear, and litter plague the oceans despite litter bylaws and disposal rules
- they harm through either ‘structural toxicity’ or ‘chemical toxicity’
- they are well documented as cause of injury and death in wildlife
what is the great pacific garbage patch?
- found in the region of the north pacific ocean
- the north pacific gyre’s rotational pattern brings in waste material from across the north pacific
what did the government of canada ban in 2023?
problematic and hard to recycle plastics
1) checkout bags
2) cutlery
3) ring carriers
4) stir sticks
5) foodservice ware
6) straws
what are microplastics?
- plastic does not break down chemically but breaks up physically into smaller and smaller pieces
- two categories:
1) primary microplastics: deliberately manufactured (microbeads, nurdles)
2) secondary microplastics: the breakdown of larger items
microplastics vary by:
size, shape, colour, origin
what are 4 methods for the sampling and analysis of microplastics?
1) sampling in environment
2) extraction and cleanup in the lab
3) visual characterization and counting using microscopy
4) forensic identification using FTIR, ramon spectrometry, pyrolysis-gas chromatography-mass spectrometry
what are deliberately designed additives?
contribute to the properties desired by the manufacturer (eg. softening, hardening, heat resisting chemicals)
what are sorbed endocrine disrupting chemicals?
- can be delivered to biota
- hitchhiking contaminants ‘vectors’ soaked up by microplastics in the environment
what are the issues with microplastics and sorbed chemicals?
- ingestion of microplastics can lead to uptake of sorbed chemicals in the GI tract of biota
- evidence remains largely lab based, with little evidence that microplastics deliver significant amounts of chemicals to biota in the real world
how do microplastics act as structural pollutants?
- structural pollutants may cause entanglement, suffocation, ingestion, GI blockage, laceration, malnutrition
- zero nutritional value
- a weight of evidence seems to be pointing to microplastics as physical or structural impediments to good in health of invertebrates, fish, and seabirds
what plastic dominants the arctic?
microfibres
- found in 96/97 samples
- averaged 49 particles/m^3
- 92% were fibres
- 73% of these were polyester
- diameter averaged 11-14 microns
what was found in samples along a 20,000km transect in the arctic?
longer, less weathered, and more abundant polyester fibres in the eastern arctic, suggesting Atlantic inputs may play an important role in microplastic contamination in the arctic
what are the characteristics of microplastics in seawater in the NE pacific ocean?
- 8 to 9200 particles/m^3
- microplastic abundance increases with proximity to urban environments in the south
- up to 80% are fibres
- mean 2080 particles/m^3 in the NE pacific vs. 49 particles/m^3 in the arctic = 42 fold difference
what is the relationship between zooplankton and microplastics?
zooplankton are mistaking microplastics for food
what was found when studying the microplastic ingestion by arctic fish?
- 21% of fish contained microplastic
- average 1.4 particles per individual
- 80% were fibres
what are the characteristics of microplastics in fish?
- nearly 400 fish species have been documented to consume microplastics, 54% of which are commercially important fish species
- occurrence of plastic ingested by marine fish has more than doubled in the last decade
- fish are consuming plastic more frequently over time
what are the effects of microplastics in fish?
- reduction in feeding and energy reserves
- impacts on reproductive output
- damage to brain and intestinal function
how are microplastics ingested by marine mammals?
1) directly through accidental consumption, for example as a result of indiscriminate feeding strategies (ie. filter feeding)
2) indirectly as a result of trophic transfer, whereby predators consume prey items contaminated with microplastics (ie. raptorial feeding)
