1. Science 3001 Science II: Earth & Life Sciences I
Oil Spills

2. Oil Spills
Oil spills are the destructive discharge of oil into the environment
Most commonly observed in water
Oils Spills sometimes kill local flora and fauna
Oil is the most common pollutant in the oceans
The bulk of oil pollution in the oceans comes from land as runoff and waste from domestic, commercial and industrial sources.
Rivers transport oil into the ocean
When ships wash out their tanks or dump their bilge water they cause about a third of the oil pollution in the oceans
Storage and transportation of oil and petroleum creates the occasional spill

3. Oil Spills
People usually conceptualize an oil spill as the accidental or intentional release of petroleum products into the environment as result of human activity (drilling, manufacturing, storing, transporting, waste management) that floats on the surface of water bodies as a discrete mass and is carried by the wind, currents and tides.
Oil spills can be partially controlled by:
chemical dispersion – acts like detergents to break up the slick
combustion – burn off the oil
mechanical containment – booms ‘surround the spill and prevent spreading
Absorption – materials suck up the oil to be removed
Skimming – special boats scrape or vacuum the oil off the water surface
When introduced in the marine environment the oil goes through a variety of transformation involving physical, chemical and biological processes: evaporation, spreading, emu1sification, dissolution, sea-air exchange and sedimentation
These degraded products include floating tar lumps, dissolved and particulate hydrocarbon materials in the water column and materials deposited on the sea bed

4. Oil Spills
Spreading of crude oil on water is affected by wind, waves and currents
Evaporation alone will remove about 50% of hydrocarbons in an “average” crude oil on the ocean’s surface
Photo-oxidation – The natural sunlight in the presence of oxygen can transform several insoluble petroleum hydrocarbons into soluble copmounds
Dispersion is οil-in-water emulsion resulting from the incorporation of small globules of oil into water
Dissolution of soluble substance in the oil into the water
Bio-degradative processes include microbial degradation, ingestion by zooplankton, uptake by aquatic invertebrates and vertebrates as well as petroleum hydrocarbons oxidizing microorganisms

5. Oil Spills

6. Oil Spills Physical effects of petroleum crude on marine bio-system
Spilled oil poses serious threats to fresh water and marine environments,
Surface resources and a wide range of subsurface organisms that are linked in a complex food chain that includes human food resources
Spilled oil can harm the environment in several ways
the physical damages that directly impact wildlife and their habitats (such as coating birds or mammals with a layer of oil)
the toxicity of the oil itself, which can poison exposed organisms
the severity of an oil spill’s impact depends on a variety of factors, including the physical properties of the oil, whether petroleum-based oils or non petroleum-based oils, and the natural actions of the receiving waters on the oil.
Biological effects of oil include:
Hazards to man through eating contaminated seafood
decrease of fisheries resources or damage to wild life such as sea birds and marine mammals
decrease of aesthetic values due to unsighty slicks or oiled beaches
modification of marine ecosystems by elimination of species
decrease in diversity and productivity
modification of habitats, delaying or preventing re-colonization.