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Oil Spills. Petroleum. Petroleum (or crude oil) is a non-renewable resource that is used as a source of energy and to manufacture petrochemicals, asphalt, and other products petroleum is mined in huge quantities, but this happens far from the places where most consumption occurs

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Oil Spills


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    1. Oil Spills

    2. Petroleum Petroleum (or crude oil) is a non-renewable resource that is used as a source of energy and to manufacture petrochemicals, asphalt, and other products • petroleum is mined in huge quantities, but this happens far from the places where most consumption occurs • this is the reason why petroleum and its refined products are transported widely by pipelines, ships, trains, and trucks • there is always a risk of accidental (or rarely, deliberate) spillage, causing severe environmental damage

    3. Canada produces considerably more petroleum than it consumes, while the U.S. imports 2/3 of its consumption ~ 95% of Canadian production occurs in sparsely populated areas of Alberta and Saskatchewan, while most consumption is in densely populated areas western Canada exports much petroleum and refined products to the U.S. and Asia, while eastern Canada imports from the Middle East and Latin America therefore, petroleum moves within, out of, and into Canada and its regions

    4. Petroleum & Refined Products Petroleum is a natural mixture of liquid & gaseous organic compounds, most of which are hydrocarbons • petroleum is a fossil fuel, as are coal, oil-sand, oil-shale, and natural gas • fossil fuels are derived from ancient biomass that: • became buried in deep sedimentary formations • and were subjected over geological time to high pressure, high temperature, and anoxia • the resulting chemical reactions eventually produced a mixture of gaseous, liquid, and solid hydrocarbons and other organic compounds

    5. Hydrocarbons Hydrocarbon molecules are entirely composed of H and C atoms Naturally occurring hydrocarbons range in complexity from: • gaseous methane (CH4) weighing 16 g/mole • through liquids such as octane (C8H18) • to solid substances with molecular weight exceeding 20,000 g/mole • a "mole" is a standard quantity, equivalent to the weight of 6.02 x 1023 atoms or molecules of a substance

    6. Hydrocarbons can be classified into groups: aliphatics have their C atoms in an open chain saturated aliphatics (or paraffins or alkanes) have a single bond between adjacent C atoms unsaturatedaliphatics have >1 double or triple bonds illustrated by these two‑C, aliphatic hydrocarbons: ethane, H3C‑CH3 ethylene, H2C=CH2 acetylene, HC=CH unsaturated aliphatics are relatively unstable and do not occur naturally in petroleum they are produced during refining and also by photochemical reactions after crude oil is spilled alicyclic hydrocarbons have some or all C atoms arranged as a ring structure (may be saturated or unsaturated) aromatic hydrocarbons contain one or more 5-C or 6-C rings in their molecular structure benzene is the simplest C6H6 ring

    7. Crude Oil Petroleums vary greatly in chemical composition, but typically consist of about: • 98% liquid hydrocarbons • <1-2% S • <1% N • V and Ni up to 0.15% • petroleum also contains dissolved gaseous hydrocarbons • the refining process separates hydrocarbon fractions by distillation at various temperatures • refining produces such products as: natural gas, gasoline, jet fuel, kerosene, heating oil, lubricating oils, waxes, and residual fuel oil (or bunker fuel) • in addition, a process known as “catalytic cracking” converts some heavier fractions into lighter, more valuable ones, e.g., those in gasoline

    8. Oil Spills The largest spills involve accidents in which petroleum or bunker fuel are discharged: • to the ocean from a disabled tanker or drilling platform • to an inland waterway from a barge or ship • to land or freshwater from a well blowout or broken pipeline • some enormous oil spills have also resulted from warfare

    9. In Canada, there are ~ 35 x 103 km of pipeline for transporting petroleum, and 227 x 103 km of natural-gas pipeline in the 1990s there were ~2,300 reported oil spills per year in Canada 42% were in the vicinity of production wells 29% were from pipelines 16% from tanker trucks the Canadian network of pipelines has spill sensors and other technology to allow sections of pipeline to be rapidly closed this allows accidents to be kept relatively small and confined some other countries do not utilize these technologies as much as in Canada, and they may suffer huge petroleum spills from overland pipelines e.g., such accidents occur commonly in northern Russia and other former Soviet republics

    10. Oil spilled on land affects relatively localized areas of terrain, because soil is absorbent of petroleum Much larger areas are affected if spilled petroleum reaches a watercourse oil spilled onto water affects an extensive area because wind & currents cause slicks to spread and disperse widely During the 1970s and early 1980s, petroleum spills into the oceans were about 3-6 x 106 tonnes/year more recently (1989), spillage was reduced to 0.6 x 106 t/yr Massive spills from wrecked supertankers or well-platforms attract a great deal of attention — and deservedly so however, much smaller but frequent discharges from urban runoff, oil refineries, and other coastal sources amount to a globally larger quantity of spillage than do rare massive spills

    11. Natural Emissions There are large natural emissions of non-petroleum hydrocarbons to the oceans • mostly chemicals synthesized by plankton, at a global rate of about 26 x 106 t/yr • contributes to the background concentration of hydrocarbons in seawater of about 1 ppb (1 µg/l) • biogenic emissions represent “natural contamination” There are also natural emissions of petroleum from oil seeps • 0.2-0.6 x 106 t/y, sometimes causing local damage • these emissions also contribute to the background concentration in seawater of 1 ppb

    12. Tanker bilge washings Discharge of oily residues from tanker storage-tanks are an important cause of marine spills • after a tanker delivers a load of petroleum to a refinery, its storage tanks are filled with seawater as a stabilizing ballast while the ship travels to get its next load of crude oil • as a tanker approaches its destination the ballast may be (illegally) discharged to the ocean, saving time & money at the port • the dumped wastewater may contain hydrocarbon residues equivalent to 1.5% of the tanker's capacity in the case of bunker-C fuel, but <1% for petroleum, and 0.1% for light products such as gasoline

    13. illegal dumping of oily bilge water has been decreasing since the 1970s, due to widespread use of a procedure called load-on-top (LOT) LOT is a process to separate and contain most oily residues before ballast water is discharged at port or to the marine environment (the residual oil is then combined with the next load) if used in calm seas, LOT can recover 99% of oily residues, but only <90% if a ship has had a turbulent passage although LOT is now widely used, some tankers still illegally discharge oily waste at sea — this pollution causes intensive and needless seabird mortality off the coasts of Canada and other countries

    14. Infamous Oil Spills Wrecked Tankers: • theTorrey Canyon in 1967 off southern England, which spilled 117 x 103 t of petroleum • Metula in the Strait of Magellan in 1973 (53 x 103 t) • Amoco Cadiz in 1978 in English Channel (230 x 103 t) • Exxon Valdez in 1989 in southern Alaska (35 x 103 t) • Braer in 1993 off Shetland Islands (84 x 103 t) Offshore platforms: • blowout of IXTOC-Iexploration well in Gulf of Mexico in 1979 (500 x 103 t)  the world’s largest-ever accidental spill • blowout in 1969 off coast of Santa Barbara in s California (10 x 103 t) • Ekofisk blowout in 1977 in North Sea off Norway (30 x 103 t)

    15. Notable Canadian spills involving tankers: theArrow in 1970 in Chedabucto Bay, NS, spilling 11 x 103 t bunker-C theKurdistan in 1979, in Cabot Strait between NF and NS, spilling 7.5 x 103 t bunker-C the Nestucca in 1988 off Washington State, which polluted shorelines on western Vancouver Island, BC; the spill volume was 875 tonnes of bunker-C

    16. A beach on Chedabucto Bay, NS, affected by bunker-C residue from the Arrow spill in 1970

    17. Spills during Warfare • during WWII, German submarines sank 42 tankers off eastern North America, spilling ~417 x 103 t • during the Iran-Iraq War of 1981-1987, there were 314 attacks on tankers, 70% by Iraqi forces • in 1983, Iraq damaged 5 tankers and 3 production wells at the Iranian Nowruz ship-loading facility, causing >260 x 103 t of petroleum to spill into the Gulf of Arabia

    18. During the brief Gulf War of 1991: the largest-ever marine spill occurred when Iraqi forces released 0.8-2.0 x 106 t of petroleum into the Gulf of Arabia from a Kuwaiti offshore loading facility this was partly an act of war, intended to impede an amphibious landing by Allied forces the largest-ever land spill occurred when Iraqis sabotaged & ignited all of the >700 wells in Kuwait – emissions of petroleum were 2-6 x 106 t/day it took 11 months to cap the blowouts 42-126 x 106 t petroleum had spilled 5-21 x 106 t accumulated as crude-oil “lakes” in the desert; most of the rest burned in the atmosphere or evaporated

    19. Fate of Spilled Oil Depending on chemical and physical characteristics of the spilled oil, various hydrocarbon fractions can selectively: • evaporate • spread • dissolve into water • accumulate as persistent residues • be degraded by microorganisms

    20. Evaporation dissipates almost 100% of gasoline spilled at sea, 30‑50% of crude oil, and 10% of bunker fuel relatively light and volatile hydrocarbons are selectively evaporated, leaving heavier residues behind evaporation is increased by warm temperatures and by vigorous wind

    21. Spreading is movement of a slick over the surface of water or land it may occur over a very large area on water, but much less on land because of the absorptive capacity of soil slicks on water are moved about by currents and wind, and may eventually wash onto a shore an experimental spill of 1 m3 of petroleum onto calm seawater created a 0.1-mm-thick slick with a 100-m-diameter after 100 minutes a slick <0.3 µm thick can be visually detected as an iridescent sheen on calm water

    22. Dissolution causes pollution of water beneath a slick • lighter hydrocarbon fractions are more soluble in water than heavier ones, while aromatics are much more soluble than alkanes • after a petroleum spill at sea, the hydrocarbon concentration in water several m beneath the slick is up to 4-5 ppm • the background concentration is 1 ppb

    23. Residual materials remain after lighter fractions of spilled petroleum have evaporated or dissolved • at sea, residual materials form a gelatinous, water‑in‑oil emulsion, known as "mousse" • mousse stranded on shore may weather to a persistent residue on rocks, or it may combine with particles of sediment to form sticky, tar-like patties • mousse that does not wash ashore weathers into a dense, semi-solid, floating asphaltic residue known as “tar balls”

    24. sticky, asphaltic materials are the most persistent residues of petroleum spills

    25. Degradation is the slow decomposition of spilled materials by biological oxidation and photo-oxidation • many bacteria, fungi, and other microorganisms can utilize hydrocarbons as a metabolic substrate • the biodegradation rate depends on the availability of key nutrients such as N & P, ambient temperature, and availability of O2 • these can be “limiting factors” to the degradation rate • lighter fractions are relatively easily decomposed by biological and inorganic oxidations, while heavier fractions resist degradation and may be persistent in the environment

    26. Toxicity Acute toxicity caused by petroleum, its refined products, or pure hydrocarbons is often associated with: • the destruction of cellular membranes • pathology caused to key organs of detoxification and excretion, such as liver and kidneys • bioaccumulation of lipid-soluble, water-insoluble hydrocarbons and organics • increased production of detoxification enzymes, known as mixed-function oxidase enzymes (MFOs)

    27. Toxic effects are influenced by environmental and biological factors, especially: chemical composition of the spilled material intensity of exposure (amount or concentration) frequency of exposure events (chronic or episodic) timing of exposure (e.g., during critical time for a species or ecosystem) thickness of the slick, nature of the emulsion, degree of weathering, & persistence of residues environmental influences on exposure and toxicity, including weather conditions, O2 status, and the presence of other pollutants toxicity of dispersants used during a clean-up sensitivity of exposed species to toxic effects

    28. Ecosystem-level damage may be influenced by: physical disturbance associated with the clean-up effects of the use of dispersants and emulsifiers, hot-water washing, substrate removal, burning, and tilling to improve aeration damage may also be influenced by effects on “keystone" species within ecological communities

    29. Effects on Seabirds Seabirds are extremely vulnerable to oil spills: • cormorants and shags • sea ducks: eiders, goldeneye, mergansers, scaup, scoters • alcids: auklets, guillemots, murres, puffins, razorbills • penguins An ill-timed oil spill can cause enormous mortality to seabirds – most species congregate in large, seasonal populations • most seabirds have slow reproduction, so it takes a long time to recover from mass mortality • e.g., murres breed after 5-yr old, lay a 1-egg clutch, and fledge only ~1 young/4 breeding adults/yr

    30. Most seabird mortality is caused by feathers being fouled with oil this causes loss of critical insulation and buoyancy – animals die from heat loss leading to hypothermia, or by drowning oil ingested while preening is also toxic eggs may be killed by only light oiling from feathers of an adult The size of a spill does not necessarily relate to its potential for causing damage to bird populations even a small spill in critical a habitat, such as a staging or wintering area, can be devastating to seabird populations

    31. Oiled birds are tragic victims of oil spills

    32. These murres were cleaned of oil residues and later released to the wild

    33. The Torrey Canyon The Torrey Canyon was a supertanker that went aground in 1967 off Wales, spilling 117 x 103 t of crude oil • hundreds of kilometres of coast were polluted with petroleum residues • 30-thousand seabirds were killed • ~ 8-thousand were captured and cleaned, but only 6% survived to be released, and post-release survival was likely very low • an intensive clean-up used large amounts of detergent & dispersant to create emulsions of oil‑in‑water that were rinsed to the ocean using pressurized water from hoses • but the emulsifiers were highly toxic to marine organisms, and exacerbated the damage caused to beaches, intertidal, and subtidal habitats

    34. where emulsifiers were not used, seaweed was damaged by oil but regenerative tissues often survived so regrowth was quick some intertidal invertebrates were rather tolerant of oiling (but not to the dispersants used) intertidal recovery was almost complete by 10 years ecological damage was always much worse wher detergent or dispersant has been used this was a critical lesson of the clean-up, and it resulted in the development of less toxic dispersants for use in oil-spill emergencies also a more judicous usage, mostly to clean high-value sites for industrial or recreational uses, or at offshore locations

    35. The Amoco Cadiz A supertanker that lost steerage and went aground in 1978 between southern England and France, spilling 233 x 103 t of petroleum • 360 km of shore were fouled (140 km heavily oiled) • many polluted beaches were intensively cleaned • mostly by removing oily sand, sediment, & residues • detergent and low-toxicity dispersant were only used to remove fouling residues in harbours, and in offshore habitats to disperse floating mousse • ecological damage caused by oil and the cleanup was less severe than with the Torrey Canyon • recovery was rapid and substantially complete within several years • but some effects on invertebrates lasted 10 yr • there was lingering damage to local alcid colonies

    36. Rocky intertidal habitat affected by petroleum spilled from the Amoco Cadiz

    37. Use of pressurized water streams to clean rocky intertidal habitat affected by petroleum from the Amoco Cadiz

    38. The Exxon Valdez This 1989 tanker accident is the most damaging ever in North America • 36 x 103 t of petroleum were spilled into Prince William Sound, s Alaska (the load was 176 x 103 t) • 40% washed onto shoreline habitat, 25% carried out of the Sound by currents, 35% evaporated, <10% was recovered or burned • the grounding of the Exxon Valdez was a reckless accident • the damage was compounded by a stunning lack of preparedness by industry and government for dealing with an oil-spill emergency out of Valdez • essential equipment was not immediately available, and it took too long to mobilize trained staff

    39. sea otters (Enhydra lutris) were the hardest-hit marine mammals, with >1,000 killed out of a population of 5-10 thousand in the Sound 357 oiled otters were captured and treated; 223 survived to be released or placed in zoos about 36-thousand dead birds were tallied, but total mortality was likely 375-435 thousand >153 bald eagles (Haliaeetus leucocephalus) were killed 400 people, 140 boats, & 5 aircraft were hired to capture and treat oiled birds (they handled 1600 birds of 71 species) 1/2 of the captured birds died – the rest were treated and released, but few likely survived because of lingering effects of hydrocarbon poisoning & stress

    40. Clean up of a shore polluted by the Exxon Valdez spill

    41. Exxon Valdez clean-up the same beach: 3 years of clean-up by humans and by natural forces a recently oiled beach

    42. Terrestrial Oil Spills Oiled plants suffer a rapid defoliation • the oil acts like a contact herbicide • trees and shrubs may survive but then suffer winter mortality • after initial post-oiling damage, many species begin to recover • some by regeneration of surviving plants • others by invasion of the oiled site

    43. a wide range of soil-dwelling microorganisms can utilize petroleum residues as a metabolic substrate they increase rapidly when soil is polluted by an oil spill microbial activity can be enhanced by: fertilizing with P and N (use oleophilic P) tilling the soil to enhance O2 availability oil spills cause severe damage to terrestrial vegetation, but relatively local areas are affected soil has a large absorptive capacity for petroleum much of the spilled oil accumulates in low spots damage in aquatic habitats is much more widespread contamination of groundwater is extremely persistent

    44. boreal forest new Norman Wells where experimental oil spills were made

    45. The petroleum spill was devastating to the ground vegetation, and recovery was slow