March 18, 2009

Oil spill cleaning methods kill fish

A Canadian study suggests detergents used to remove ocean spills of diesel oil harm more fish than the spills themselves.

The detergents may be the best way to treat spills in the long term because the dispersed oil is diluted and degraded, said Queen's University Professor Peter Hodson. But in the short term, they increase the bioavailability and toxicity of the fuel "¦ by 100 fold.

The detergents are oil dispersants that decrease the surface tension between oil and water, allowing floating oil to mix with water as tiny droplets. Hodson said such hydrocarbons pass easily from water into tissues and are deadly to fish during 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 said.

The researchers said they also determined that although chemical dispersants aren't typically used in freshwater, turbulent rivers can disperse spilled diesel and create similar negative effects.

The study, which included Allison Schein, Jason Scott and Lizzy Mos, is published in the journal Environmental Toxicology and Chemistry.