Oil Spills

Oil spills are releases of petroleum into water bodies, with significant effects on marine and coastal environments.

Definition

The accidental or deliberate release of liquid petroleum into water, where it spreads, weathers, and affects organisms, shorelines, and ecosystems.

Scope

This topic covers the release of crude oil and petroleum products into aquatic environments and their environmental fate and effects. It addresses the sources of marine oil inputs, the weathering processes that transform spilled oil such as spreading, evaporation, dissolution, emulsification, and biodegradation, the impacts on wildlife and shorelines, and the principal response and cleanup techniques. Bioremediation of oil connects to broader remediation methods.

Core questions

• What are the major sources of oil entering the sea?
• How does spilled oil weather and change over time?
• How do oil spills affect wildlife and shorelines?
• What methods are used to respond to and clean up oil spills?

Key theories

Oil weathering processes

Once spilled, oil undergoes spreading, evaporation, dissolution, emulsification, photo-oxidation, and biodegradation, which together change its composition, behavior, and persistence in the environment.

Diverse inputs of oil to the sea

Oil reaches the ocean from natural seeps, extraction, transportation accidents, and land-based runoff, so dramatic tanker spills are only part of total petroleum inputs.

Clinical relevance

Oil spills damage marine and coastal ecosystems, harm wildlife, and disrupt fisheries and coastal economies; understanding oil behavior and effects underpins spill response, cleanup, and damage assessment.

Evidence & guidelines

Spill response and impact assessment draw on syntheses such as the National Research Council's review of oil in the sea; these are described here to explain practice rather than as prescriptive guidance.

History

Major tanker accidents and offshore blowouts, including high-profile events in the late twentieth and early twenty-first centuries, drove advances in spill prevention, response capability, and the science of oil fate and effects.

Seminal works

• nrc2003oil
• fingas2013
• manahan2017

Frequently asked questions

What happens to oil after it is spilled in the ocean?

Spilled oil spreads into a slick and then weathers: lighter components evaporate or dissolve, the oil may form water-in-oil emulsions, and microbes gradually biodegrade it, so its composition and toxicity change over days to years.

Are tanker accidents the main source of oil in the sea?

No; while tanker spills are dramatic, large amounts of oil also enter the sea from natural seeps, extraction and transport operations, and especially diffuse land-based runoff, which together can exceed inputs from accidents.