Photo: ingridtaylar via Flickr
Oil spills just got messier. According to a biologist at Queen's University, the detergents used to clean oil spills may be more harmful to fish than the oil that gets spilled. Biology professor Peter Hodson warns that the oil-dispersing detergents that do such a bang-up job of degrading and diluting oil in the long term increase the bioavailability and the toxicity of the oil to rainbow trout by 100-fold in the short term. The Dangers of Oil Spill Clean-Ups Explained
From Queen's News Centre
The detergents are oil dispersants that decrease the surface tension between oil and water, allowing floating oil to mix with water as tiny droplets. Dr. Hodson and his team found that dispersion reduces the potential impacts of oil on surface-dwelling animals, While this should enhance biodegradation, it also creates a larger reservoir of oil in the water column.
This increases the transfer of hydrocarbons from oil to water, Dr. Hodson explains. The hydrocarbons pass easily from water into tissues and are deadly to fish in the early stages of life. "This could seriously impair the health of fish populations, resulting in long-term reductions in economic returns to fisheries," he says.
Other Discoveries About Oil Dispersal
Other methods of oil dispersal, both chemical and natural, are also damaging to the fish. Oil diffused by the rushing current of a freshwater river is just as harmful to fish populations as the oil dispersed by the chemical detergents.
It doesn't matter if the oil is being dispersed by chemicals or by the current," says Dr. Hodson. "Now that we know how deadly dispersed oil is, it is important to assess the risks of diesel spills to fish and fisheries in terms of the spill location, and the timing relative to fish spawning and development.
Detergents also Dangerous to Coral Reefs
Coral exposed to detergent-treated oil dies faster than coral exposed to plain old crude oil. Untreated oil smothers the coral, and the detergent-treated oil poisons it. (The untreated oil still poisons the coral but to a lesser extent.)
Amy Merten, an environmental scientist at the U.S. National Oceanic and Atmospheric Administration (NOAA), said the study gives information on a worst-case scenario that should be considered in trade-off decisions. This includes choosing whether to disperse oil into the water and risk harming coral versus getting the oil slick off the surface of the water "so birds, mangroves, and nesting turtles aren't as affected," she said.
Some scientists want to see these detergents banned, except in the cases of shore-bound spills that will smother reefs entirely.
Are There Alternatives to Detergents?
Essentially, there are mechanical methods [such as skimmers], in-situ burning or dispersants," Merten explained. "Generally, in open water, there is a very short window for using any method since the slick will spread and move with the wind and currents. Dispersants will continue to be considered as an option. After the oil spills, no one wins. Our job is to try to minimize further impacts, and there may be a time when dispersants help us do that for a portion of the spill.
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