Oil Spills

Pollution in the ocean is a major problem that is affecting the ocean and the rest of the Earth. Pollution is the ocean directly affects ocean organisms and indirectly affects human heath and resources. Oil spills is one of the harmful materials that are a major source of pollution in the ocean. “Oil spills stem from accidents involving tankers, barges, pipelines, refineries, and storage facilities, often while the oil is being transported to its users.” (NOAA 2012)

Based on information from NOAA, oil can be categorized into four different types of oil ranging from very light to heavy oils, which are different depending on each of their viscosity, volatility, and toxicity. Oil’s resistance to flow is known as viscosity. Volatility is described on how fast the oil evaporates into the air. How poisonous the oil is to the organisms and humans is referred to as toxicity. The four different types of oil can affect the environment in extremely different ways. In addition, some oil spills are harder to clean up than others. Most oil has a density less than water, so it floats. Oil tends to spread into a thin layer on the water surface as sheen.

Once in the water, oil undergoes weathering, a process that describes the physical, chemical, and biological changes that occur when oil interacts with the environment. “Weathering reduces the more toxic elements in oil products over time, as exposure to air, sunlight, wave and tidal action, and certain microscopic organisms degrades and disperses oil.” (PFMC 2008) Also, weathering rates depend on factors such as type of oil, weather, temperature, and the type of shoreline and bottom that occur in the spill area. One of the types of oil spills is a very light oil spill, which is highly volatile and concentrations of toxic compounds. Very light oil spills tend to evaporate quickly, which are one of the most acutely toxic oils and generally affect aquatic life that live in upper water column.

Also, very light oil spills such as jet fuels and gasoline “localized, server impacts to water column and interidal resources” (NOAA 2012) and have no possible clean up available. Another type of oil spills is light oil, most often known as diesel fuel, which not sticky or viscous, compared to black oils. Light oils are moderately volatile and concentrations of toxic compounds that leave around one-third of the oil spill after a couple days. Light oils have a film on intertidal resources and have the potential to cause long-term contamination. “When small spills do strand on the shoreline, the oil tends to penetrate porous sediments quickly but also tend to be washed off quickly, waves and tidal flushing.

Thus, shoreline cleanup is usually not needed.” (NOAA 2012) According to the information from NOAA, the third type of oil spill is medium oil, which are most crude oils. Medium oils are less likely to mix with water. About one-third of medium oils with evaporate within twenty-four hours. The third type of oil contamination of intertidal areas can be severe and long-term, which impacts waterfowl and fur mammals. However, the clean up of medium oil can be most effective if conducted quickly.

“Crude oil blends vary tremendously in their chemical composition, depending on the geographical location of their origin and the particular compounds mixed with the petroleum products.” (NOAA 2012) The most abundant compounds in crude oils are hydrocarbons. The forth and last type of oil spills is heavy oils, which is known as No. 6 fuel oil do not readily mix with water and have far less evaporation and dilution potential. “Heavy oil spills have heavy contamination of intertidal areas and tend to weather slowly.” (PFMC 2008) Like medium oil spills, heavy oil spills also server impacts to waterfowl and fur mammals. Heavy oil spills have long-term contamination of sediments possible.

“The most important factors determining the impact of No. 6 fuel oil contamination on marshes are the extent of oiling on the vegetation and the degree of sediment contamination from the spill or disturbance from the cleanup.” (NOAA 2012) Heavy oils can float, mix, sink, or hang in the water. These oils can become oil drops and mix in the water, or accumulate on the bottom, or mix with sediment and then sink, which is why the shoreline cleanup can be difficult under all conditions in heavy oil spills and are usually long-term. Bases on information from NRDC, oil causes harm to wildlife through physical contact, ingestion, inhalation, and absorption. “Floating oil can contaminate plankton, which includes algae, fish eggs, and the larvae of various invertebrates.” (NRDC 2005)

Fish that feed on these organisms can subsequently become contaminated. Larger animals in the food chain, including bigger even humans may then consume contaminated organisms. “Initially, oil has the greatest impacts on species that utilize the water surface, such as waterfowl and sea otters, and species that inhabit the near shore environment.” (NRDC 2005) Although oil causes immediate effects throughout the entire spill site, it is the external effects of oil on larger wildlife species that are often immediately apparent.


NOAA 2012. Research for oil spills. National Oceanic and Atmospheric Administration, How Toxic is Oil? Available from: http://response.restoration.noaa.gov/oil-and-chemical-spills/significant-incidents/exxon-valdez-oil-spill/how-toxic-oil.html

NOAA 2012. Research for oil spills. Silver Springs, MD. US Department of Commerce, National Oceanic and Atmospheric Administration, Undersea Research Program. Available from: http://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills

NRDC 2005. [Last revised 3/10/2005] National Resource Defense Council. The Arctic National Wildlife Refuge Oil Development Damages Air, Water and Wildlife. New York, NY: Web Page article: Main page/Life on the Coastal Plain/Damage Caused by Oil Development. Available from: www.nrdc.org/land/wilderness/arcticrefuge/facts2.asp

PFMC 2008. Pacific Fishery Management Council, PROJECT TITLE: The Ecological Role of Natural Reefs and Oil and Gas Production Platforms on Rocky Reef Fishes in Southern California. Available from: www.pcouncil.org/bb/2005/0605/ag_c3d_pc1_pt10.pdf-2005-06-08