OIL'S WANDERING PATHS POWER POINT NOTES

Transcription

1 OIL'S WANDERING PATHS POWER POINT NOTES SLIDE 1: OIL PROCESSES, SPILLS, AND WEATHERING PRESENTATION SLIDE 2: WHAT CAN YOU THINK OF THAT IS MADE FROM PETROLEUM PRODUCTS? Petroleum means oil, another word (scientific) is hydrocarbon since all petroleum products are made of hydrogen and carbon molecules Have students brainstorm things that are made from oil products.write results on board. Results should include: petroleum/hydrocarbons products: fuel (gas, diesel), plastics, motor oil, waxes, petroleum jelly, lipstick, personal care products, lubrication, asphalt/pavement, medicines, ink, fertilizers/pesticides, paint/varnishes, and electricity SLIDE 3: HOW MUCH OIL DO WE USE? The US uses about 700 million gallons of oil every day. The world uses nearly 3 billion gallons each day. That this much oil must be transported every day is truly hard to imagine. However, if you think about all the ways we use oil, perhaps these numbers are not so surprising. We use oil to: fuel our cars, trucks, and buses, and to heat our houses lubricate machinery large and small, from bicycles to printing presses make the asphalt we use to pave our roads make plastics, such as the toys we play with and the portable radios and CD players we listen to make medicines, ink, fertilizers, pesticides, paints, varnishes, and electricity make up waxes contained in petroleum jelly, lipstick, and many personal care products. with different chemical characteristics. SLIDE 4: WHERE DOES OIL COME FROM AND GO? Explain to students that crude oil is taken directly from its rocky source below ground or under the sea. discuss how is oil removed from the earth, transported and refined. Oil is spilt at each of these steps with the majority of oil spills occurring during transportation. SLIDE 5: HOW DO OIL SPILLS HAPPEN? Oil spills are caused by accidents moving oil usually involving tankers, barges, pipelines, refineries, and storage facilities, usually while the oil is being transported to us, its users, via rivers, bays, and the ocean. Spills can result from: People making mistakes or being careless (Exxon Valdez)

2 Equipment breaking down (Deepwater Horizon) Natural disasters such as hurricanes Deliberate acts by terrorists, countries at war, vandals, or illegal dumpers SLIDE 7-11: WHERE DO THE MAN- MADE OIL SPILLS COME FROM? Man-made marine oil sources: Tanker Accidents: 15% Tanker Operations: 5% Oil Drilling: 6:% Aircraft Fuel: 1% Atmospheric Deposition: 8% Runoff: 21% Small Ships and Boats: 41% Other: 3% Highlight that only 26% of all the manmade oil in the ocean comes from drilling and tankers; most of it is coming from small ships and boats like those in our harbor (41%) and runoff (21%). SLIDE 12: WHAT HAPPENS ONCE THERE IS AN OIL SPILL? In general, the molecules that make up oils and waxes adhere to one another and are less dense than water; thus, oil floats on salt water (the ocean) and usually floats on fresh water (rivers and lakes). Very heavy oil can sometimes sink in fresh water, but this happens very rarely. SLIDE 13: OCEAN SURFACE SPILLS SURFACE TRANSPORT Oil usually spreads out rapidly across the water surface to form a thin layer that is called an oil slick. Surface slicks are transported by wind and ocean currents (advection). Spreading rates are influenced by: Sea state Wind Rule of thumb: slicks move at 3% (1 to 5) of the wind speed 10m above the water s surface Coriolis Effect causes ~10-20% drift to the right of the wind direction Currents Slick moves at 100% of surface current speed Product viscosity Physical barriers (shorelines, islands, debris) The spread is not uniform, but has an irregular in shape and thickness. 90% of a spill s volume is contained in 10% of its area. As the spreading process continues, the layer becomes thinner and thinner, finally becoming a very thin layer called a sheen (or a film), which often looks like a rainbow. (You may have seen sheens on roads or parking lots after a rain.) SLIDE 14: DEEP WATER SPILLS VERTICAL TRANSPORT

3 Oil droplets become entrained in the water column (by wave action, wind mixing) and transported by subsurface currents. distribution of droplet sizes smaller droplets are transported deeper and longer depth of droplet transport: initially proportional to wave height (approx. 1.5x wave height) subsequent vertical transport depends on: vertical diffusion and buoyant rise (wave height, wind, density stratification) droplets can also be transported deeper in convergence zones droplets will continue to rise to the surface after transport (unless it interacts with suspended particulate matter) Subsurface spills If oil mixed with natural gas (blowout) - Gas adds buoyancy - Gas and oil form droplet/ bubble plume, traps seawater as it rises If oil in shallow water: rises as a single plume, then spreads on surface In deep water: other factors in play: currents, density stratification - The plume rises like a smokestack rises vertically a certain distance, then tips over and moves mostly horizontally, rising very slowly because the droplets become so small that they don t have enough buoyancy to rise quickly (the amount the plume travels vertically before tipping is the plume separation distance ) - Larger bubbles and droplets rise faster, separate from rest of plume (droplet rise velocity is proportional to droplet diameter) The smallest droplets begin to spread horizontally almost immediately from the wellhead, rising very slowly; they may never reach the surface - The plume is much longer and thinner SLIDE 15: HOW MUCH OIL DID THE EXXON VALDEZ SPILL? Before the Deepwater Horizon oil spill in 2011, the previous largest oil spill to occur in the United States was the Exxon Valdez spill into Prince William Sound, Alaska, on Good Friday March 24, 1989 at 12:04am. The tanker collided with Bligh Reef outside of Valdez, Alaska. Captain Joseph Hazelwood was commander of the vessel. The Exxon Valdez, a medium-sized oil tanker, ran aground on a reef to cause this spill of almost 11 million gallons/257,000 barrels of crude oil. While this was a big spill, it was actually only a small fraction of the oil less than 2 percent of what the United States uses in one day!

4 These big numbers are hard to relate to everyday life, so let's make some comparisons. To better understand how much 11 million gallons of oil is, check the table below. It shows how many familiar rooms or buildings would be filled up by the approximate amount of oil spilled from the Exxon Valdez. For example, that much oil would have filled up nine school gyms or 430 classrooms. See graph below:

5 Total Volume Gallons Gyms Houses Classrooms Living Rooms Exxon Valdez Oil Spill 10,800,000 > School Gymnasium (50' X 50' X 65') Average House (40' X 40' X 8') Average Classroom (20' X 20' X 8') Average Living Room (12' X18' X 8') 1,274, , , , Most of the oil residue scientists find in Prince William Sound originated with the Exxon Valdez spill. Other potential sources scientists have identified include diesel fuel, nonspecific combustion sources that could include anything from wood stoves to vessel exhaust, and spilled oil not linked to the Exxon Valdez. SLIDE 16: CAN YOU NAME ANY OTHER OIL SPILLS? Students should brainstorm any other oil spills. If possible, let students spend 5-10 minutes on the internet researching oil spills. They should list the details of one major oil spill in the worksheet. Here is a list of the top 50 oil spills in the world: Discuss oil spills with which students may be familiar, such as the spill off the coast of Rhode Island in January 1996 and the one in Prince William Sound in Alaska in You may wish to check your library or online sources for magazine and newspaper articles about actual oil spill events, perhaps an incident that occurred close to your region to make the topic more relevant to students. SLIDE 17: TOP WORLD OIL SPILLS These are three of the top oil spills, releasing the largest quantities of oil into the environment. (according to Wikipedia s List of Oil Spills) - The Kuwaiti Oil Fires were caused when Iraqi military forces set fire to approximately 600 oil wells as they retreated from Kuwait in This was part of a scorched earth policy. The fires were started in January and February 1991 and the last one was extinguished in November. The fires washed the Persian Gulf region in poisonous smoke, soot and ash, creating huge pollution problems.

6 - Also resulting from the Gulf War in 1991, this oil spill resulted when Iraqi forces opened valves of oil wells and pipelines as they retreated from Kuwait. The slick created by the oil spewing into the Persian Gulf was up to 101 miles by 42 miles and was 5 inches thick. - The Deepwater Horizon oil spill resulted when an oil rig in the Gulf of Mexico exploded, killing 11 men and caused oil to spill unabated into the ocean for three months; it may still be seeping oil. To date, this is the largest accidental marine oil spill. SLIDE 18: HOW DOES THIS COMPARE WITH THE EXXON VALDEZ OIL SPILL? How do these massive amounts of oil spilled in these world oil spills compare with the Exxon Valdez Spill in Prince William Sound? A German shepherd weighs about 60 pounds, while a blue whale weighs abou 160 tons. That s over 5,000 times the weight of a German shepherd. That s how much more oil was lost in the Kuwaiti Oil Fires than in the Exxon Valdez Oil Spill. Think about how much damage the Exxon Valdez spill caused here and it wasn t even that large of a spill on the scale of world oil spills. SLIDE 19: WHAT HAPPENS TO OIL ONCE IT SPILLS? Once exposed to the environment, oil immediately begins to undergo weathering through a number of processes (lots of information below, go into as little or much detail as your students would like): Evaporation Photo-oxidation Emulsification/mousse (this is the mousse in the Oil Spill Clean-Up activity) Biodegradation Sedimentation (this is the Sediment Penetration Lab) Evaporation

7 most rapid weathering process evaporability depends on type of oil: o 20-50% of crude oils o 75%+ of refined petroleum products o <10% of residual fuel oils Low-molecular-weight volatile compounds evaporate quickly o Remaining heavy components more easily form emulsions o As light compounds evaporate, the specific gravity of the remaining product increases, making it more likely to sink Evaporation decreases toxicity Factors hindering evaporation: o Oil phase is not well-mixed o Entrained water (emulsion) o Slick size and thickness o Air temperature- less evaporation in colder temperatures Photo-oxidation chemical compounds in oil are structurally modified to more toxic products forms higher-molecular-weight products forms toxic polar products that mix readily with water and emulsify easily Emulsification (water-in-oil) [This is what is simulated in the PWSSC/Oil Spill Clean-Up Lab] Forms a mixture of small droplets of oil and water. Water-in-oil emulsions are frequently called chocolate mousse, and are formed when wave action causes water to become trapped inside viscous oil. Emulsions may linger in the environment for months. can increase volume by a factor of 3 can increase viscosity by 1000x emulsifying agents are high-molecularweight components of crude (asphaltenes and resins) o prevent water droplets from recoalescing o enable formation of stable emulsion low-molecular-weight components prevent emulsification by controlling solubility of emulsifying components [4 states of water in oil] 1. stable emulsion a. can be 1000x more viscous than starting product b. high elasticity c. reddish or red-brown color (lightened by dilution) d. can linger for months or even years 2. unstable emulsion a. rapidly decompose to original states after mixing energy is removed b. no elasticity

8 3. meso-stable emulsions with properties between stable and unstable 4. entrained water (water droplets trapped in oil) fatty acids and CO2 in the course of days to months Emulsion formation and stability is affected/determined by: oil composition (concentration of lowmolecular-weight vs. high-molecularweight compounds): high-molecularweight compounds are needed to form stable emulsions; light refined oils do not emulsify easily starting viscosity of oil: if the initial oil has very high or very low viscosity, it will not be able to form a stable emulsion kinetic energy relative to mass of oil higher mixing energies create more stable emulsions Biodegradation a natural process that takes weeks to months in open water components of oil are degraded by hydrocarbon-degrading microbes (bacteria, fungi, yeasts) oil contains thousands of chemical components; only a fraction are biodegradable (e.g. waxes, alkanes, aromatic hydrocarbons) microbes consume these biodegradable components and break them down to

9 A special case: microbial and sediment interactions after the Deepwater Horizon blowout Microbial slime integrated with oil emulsion; oil causes microbes to bloom, then sink to the bottom with the oil as microbial waste weighs them down.this causes rapid sedimentation on the seafloor. Effects of oily layers of sediment and organisms: Killed benthic filter feeders (suffocation or toxicity mostly suffocation from too-rapid sedimentation) No microbial activity in oily sediment Will have wide, unpredictable effects for many years to come because of benthic-pelagic coupling; normal process of recycling of nutrients from the seafloor is disturbed Benthic organisms (e.g. brittle stars) normally oil-tolerant (found often at natural seeps) Oil-sediment interaction (flocculation/sedimentation) [This is what is simulated in the PWSSC/Oil Sedimentation Lab] oil forms aggregate with sediments and minerals, marine snow; disperses throughout water column sediment particles prevent oil from re-coalescing smaller particles (clay vs. sand) are more effective at stabilizing oil aggregations may sink to ocean floor, or remain suspended Flocculation: dispersed particles form larger-sized clusters by adhesion SLIDE 20: WHAT ARE SENSITIVE HABITATS TO OIL SPILLS? Oil affects habitats differently. From the Global Marine Oil Pollution Information Gateway: The U.S. Coastguard have listed shoreline types, from the least (low figures) to the most sensitive ones to oil pollution: Exposed rocky cliffs and seawalls [LEAST sensitive] Wave cut rocky platforms Fine to medium-grained sand beaches Coarse-grained sand beaches Mixed sand and gravel beaches Gravel beaches/riprap Exposed tidal flats Sheltered rocky shores/man-made structures Sheltered tidal flats Marshes [MOST sensitive] It should be noted that other shore types and shallow underwater habitats are also very sensitive to oil pollution, including: Mangroves (And according to ITOPF: "Leaving residual oil to weather and

10 degrade naturally is usually recommended for sensitive shoreline types such as salt marshes and mangroves, because they have been shown to be more easily damaged by the physical disturbance caused by clean-up teams and vehicles than by the oil itself. If any cleaning is attempted, it should be carried out with specialist guidance and advice.") Coral reefs See also NOAA.