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2 - The phases of an oil spill and scientific studies of spill effects
- Edited by John A. Wiens
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- Book:
- Oil in the Environment
- Published online:
- 05 July 2013
- Print publication:
- 18 July 2013, pp 37-53
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Summary
Introduction and overview
Following a marine oil spill, it is important to know where the oil goes, how it changes chemically, how long the oil persists in various environmental compartments such as water or sediments, and what biological resources are affected. As an oil spill progresses over time, the behavior of the oil and the impacted areas and levels of risk to people and biological resources such as fish and wildlife change. Scientific studies provide the most benefit to cleanup efforts and the protection of people and biological resources in the area when they are coordinated and focused on the most pressing questions based on the phase of the oil spill. Over several decades, previous marine oil spills have shown a consistent pattern; understanding this pattern can help predict where the oil will go, how it changes chemically, where it will persist, and what living things are likely to be affected. Similarly, this predictability, coupled with specific observations at each spill, can help to provide a framework for designing and conducting studies that can address key questions at critical junctures in the evolution of the spill.
Water and air are the first environmental media affected during the early phase of any marine spill. Animal and plant life (or “biological resources”) can be affected immediately – as can humans involved in spill cleanup. The initial exposures to the chemicals in petroleum and the resulting effects can be acute, but short-lived. This is because once the spilled oil is no longer moving on or in the water, concentrations of harmful chemicals decrease rapidly owing to dilution, dispersion, and degradation (collectively known as “weathering”). Likewise, the evaporation of the volatile hydrocarbon components of fuels or crude oil immediately following a spill first increases, then decreases. By contrast, the effects on shoreline biological resources from oil that reaches land may persist. The last area potentially to be affected is bottom sediments, where oil can be transported before or after it reaches land (Chapter 4).
6 - Fate of oil on shorelines
- Edited by John A. Wiens
-
- Book:
- Oil in the Environment
- Published online:
- 05 July 2013
- Print publication:
- 18 July 2013, pp 116-143
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Summary
Introduction
Most oil tanker accidents occur near land. So when a marine oil spill occurs, it is usually not long before the spilled oil reaches shorelines. The shoreline is where the potential for harm to the environment and biological resources is the greatest, and where media attention and public concerns usually focus. Therefore, it is essential to determine the distribution, amount, composition, and fate of spilled oil on shorelines. This information forms the foundation for management decisions about cleanup during the early phases of the spill, assessments of long-term exposure and injury to biological resources, and long-term restoration strategies after the initial cleanup.
In this chapter, we consider the fate of shoreline oil following the Exxon Valdez oil spill, beginning with oil coming ashore in Prince William Sound (PWS) in 1989. This chapter picks up where Chapter 3 left off, describing where the oil was deposited, why some locations were oiled more than others, and how oil disappeared over time and why, in a few isolated locations, it persisted.
11 - Shoreline biota
- Edited by John A. Wiens
-
- Book:
- Oil in the Environment
- Published online:
- 05 July 2013
- Print publication:
- 18 July 2013, pp 241-262
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Summary
Introduction
Coastal shorelines teem with life. The intersection of the land with the sea, combined with tidal fluctuations and coastal currents, creates an array of habitats that supports an amazing diversity of plants and animals – limpets, starfish, anemones, crabs, rockweed, eelgrass, snails, tubeworms, and the like – that live on the surface and in the sediments of the intertidal zone. When floating oil from a marine oil spill strikes a shoreline, the potential effects on these organisms (the shoreline biota) may be severe. Even species that are not directly affected by spill may suffer its effects if the shoreline prey on which they feed are diminished. Understanding how a spill affects the shoreline biota is therefore important to assessing the potential effects on the broader shoreline and coastal ecosystems.
During the Exxon Valdez spill, oil first spread over shorelines in Prince William Sound (PWS) and later extended outside of PWS to the Kenai Peninsula, Kodiak Island, and Alaska Peninsula (see Map 1, p. v). The effects of the spill and the need to respond rapidly were of enormous concern, particularly within PWS, where oil quantities and potential toxicity were greatest. In this chapter, we discuss three major programs undertaken to assess the effects of the Exxon Valdez oil spill on shoreline biota in PWS, including studies to determine the effects of intensive cleanup efforts.