14: Oil spills Flashcards
What is crude oil
Liquid mixture of hundreds of different petrochemicals, later refined to make products such as gasoline, heating oil, etc
What is diluted bitumen (dilbit)
Bitumen (crude oil + sand) diluted with lighter petroleum to make it less viscous
What is petroleum
Broad category that includes both crude oil and petroleum products. The terms oil and petroleum are often used interchangeably.
Main way we transport fuel in Canada
Pipeline
Small amounts marine and rail
Four major pipelines in Canada? Where does most of Canada’s oil go?
- Trans Mountain (Edm to BC)
- Keystone (AB to USA)
- Express (AB to USA)
- Enbridge (Edm to USA)
99% goes to the USA
Moving petroleum by sea? Major ports?
Most tanker traffic is to the USA, rest overseas
Ports:
- Vancouver
- Kitimat, BC
- Saint John, NB
- Come by Chance, NF&L
Characteristics of terrestrial oil spills? Marine?
Terrestrial:
- most common
- usually ruptured pipeline
- >1000 incidents in Canada in past decade
- impacts localized area
Marine:
- less frequent, but more petroleum
- single spill can release as much as an entire year of terrestrial spills
- damages disperse, oil transported across by ocean currents
Fate of spilled petroleum through natural processes in water
- Evaporation
- Spreading
- Dissolution
- Residual materials
- Degradation
Slides 12, 17 images
What is evaporation of petroleum?
Evaporation of fumes and vapors reduces volume of spillage
Can eliminate 100% gasoline, 50% crude oil
What is spreading of oil
Movement of an oil slick over water or land. Slow on land (soil absorbent), quicker on water (currents and wind)
What is dissolution of oil
Pollution of the water beneath an oil slick
Lighter hydrocarbons become dissolved in water
What are residual materials in oil spills
Heavier hydrocarbons form a gelatinous emulsion known as mousse, can wash up onto shorelines or sink
What is degradation of oil
The slow decomposition of petroleum by either microbes (biodegradation) or photo-oxidation by UV radiation
Fate of spilled petroleum on land
- localized impacts (unless very large)
- soils high in organic matter than can absorb petroleum
- tends to accumulate in low spots on landscape
What makes petroleum toxic
- contains many volatile organic compounds (VOCs) such as benzene, toluene
- VOCs are carcinogens, can cause neurological and reproductive damage, and are irritants
Acute toxicity of oil
- some hydrocarbons destroy cellular membranes, killing tissues
- clean up process can also kill organisms
How can oil spills cause organisms to suffocate?
- surface waters become supersaturated with O2 due to atmospheric exchange
- oil slicks form a barrier between air and epilimnion (surface water) which prevents atmospheric exchange
- dissolved O2 decreases = epilimnetic organisms can suffocate
Biggest concern about oil in soil? Affects on organisms
Biggest concern is petroleum seeping into groundwater
May kill soil microorganisms, arthropods, and higher organisms = disrupts food web
Effects of oil on coastal areas
- oil can be toxic to marsh and coastal grasses
- kill the grasses, reduce the protection from wind and water = erosion
Four ways oil spills are cleaned up
- Mechanical recovery: physical containment, collection of spilled oil
- In-situ burning: controlled burning of spilled oil to remove it (creates GHG)
- Chemical recovery: use of dispersants or gelling agents to either break down the oil into smaller droplets or to congeal it
- Bioremediation: use of fertilizers and nutrients to increase microorganism growth, which biodegrade the oil
When are dispersants usually used? Example?
In choppy waters, when other methods are ineffective
E.g. COREXIT
- used to clean up Deepwater Horizon
- but may be more acutely toxic than oil
Slides 30-35
Cleaning
What do gelling agents do? Why are they good? Problem?
Solidifiers that physically bond with oil, forming a rubbery solid
Low toxicity, low flammability
May be able to recycle solidified oil
Problem: expensive and need large volume
What is bioremediation? How do we do it
Use of microorganisms to break down and degrade petroleum
Can seed organisms into spills, or fertilize spills to increase their pops
Best ways to clean terrestrial spills
- Easiest to just remove the affected soil from the site
- Bioremediation can be used
- Use of electrical resistance heating (electrodes that warm the soil and heat make hydrocarbons evaporate)
What was a recent oil spill?
Huntington Beach off Southern California
October 2, 2021
When was Deepwater Horizon oil spill? What went wrong?
2010, 5 million barrels
Piping failure and buildup of natural gas filled up the drill column which exploded
Blowout preventer malfunctioned and manual override was not enacted fast enough
What problems were there at the Deepwater Horizon site previously?
- Previous equipment malfunction
- Faulty concrete
- Lied on safety record
- Ignored signs of problem
- Ignored workers concerns
Slides 44,45
Deepwater horizon images
How was the oil from Deepwater Horizon cleaned up? How much was paid?
- 23.5 million liters of oil skimmed
- 42 million liters burned
- 62.5 million liters dispersed using COREXIT
British Petroleum required to pay 18.7 million USD for cleanup and ecological restoration
Examples of species affected by deepwater horizon
- Laughing gull 32% decline
- 20% of all juvenile Kemp’ Ridley sea turtles died
- habitats of 4 sea turtle species were degraded
- bottlenose dolphin pops have decreased 50% in one Louisiana bay (direct mortality and reduced repro)
Slides 51, 52
After the oil DH
What is happening in the gulf of mexico now? Why is recovery so slow?
Impacts still being studied
Most oil is weathered by now, fishery closures have been lifted
Oil linked to birth defects and deaths of marine orgs
Recovery by animals is slow due to bioaccumulate (and biomagnification) of toxic COREXIT
Slides 54-56
Exxon-Valdez oil spill
What have we learned from the Exxon-Valdez oil spill
Happened in 1989
Weathered oil will persist, has been observed on Alaskan cost 16+ years after spill
Chronic oil exposure will impact wildlife
- chronic ingestion from grooming
- reduced reproduction, increased mortality in fish, mammals, birds
- bioaccumulation will occur
Indirect effects of the Exxon-Valdez oil spill
- Food web disruptions from trophic cascades
- reduced biogenic habitat
- loss of keystone species
- disruption of social species e.g. orcas
Types of mechanical recovery
- containment booms
- skimmers and sorbents
