Review of potential environmental consequences of the British Petroleum Deepwater Horizon well blow out spill, April 2010.
An unknown but enormous quantity of crude oil is being released into the Gulf of Mexico from a depth of 5,000ft in the Mississippi Canyon 252 lease block (28o44.20’N, 88o23.23’W). There are many different ecosystems in the Gulf basin, and the extent to which they will be impacted depends on how much oil is released, where it goes, and also how it is treated. Mitigation can take the form of physical barriers or booms that block surface slicks and prevent the oil washing up on shore, igniting slicks to burn them from the surface, and applying dispersant chemicals that break down the surface slicks and allow them to sink in the water column. Oil spill dispersants do not reduce the total amount of oil entering the environment; they simply change the chemical and physical properties of the oil, thereby changing its transport, fate, and potential effects. Dispersants also contain potentially dangerous compounds, but the chemistry of each brand is proprietary so the toxic effects are unknown. Small amounts of oil will disperse naturally into the water column through the action of waves and other environmental processes. The objective of applying dispersant is to increase the amount of oil that physically mixes into the water column, reducing the potential that a surface slick will contaminate shoreline habitats and fauna, or impact organisms that come into contact with the water surface (birds, marine mammals, turtles etc). However, by promoting dispersion of oil into the water column, dispersants increase the potential exposure of water‐column and benthic biota to spilled oil. Dispersant application therefore represents a conscious decision to increase the hydrocarbon load on one component of ...
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