THE loss of the oil tanker Prestige off the coast of Spain last week has set in motion a wave of finger pointing, diplomatic tension and ecological angst. But the accident has highlighted just how little agreement there is among scientists over the environmental impact of oil spills at sea.
In a sharp riposte to environmentalists who said the ship should have been towed into harbour and efforts made to empty its tanks of the 77,000 tonnes of heavy fuel oil, some marine biologists have praised the Spanish government for its decision to tow the tanker out into the deep Atlantic, where it broke in two last week and sank to the ocean floor, leaving behind oil slicks tens of kilometres long.
鈥淢any toxic components in the fuel oil will evaporate or disperse into the water before the slicks reach land,鈥� says Jim Readman, a pollution expert at the Plymouth Marine Laboratory. Bringing the ship to shore would only have increased the risks of widespread pollution, he says.
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Paul Kingston of Heriot-Watt University, Edinburgh, who investigated the spill from the Exxon Valdez in Alaska, goes further, saying much of the debate over the ecological damage of oil spills is one of semantics. 鈥淲hat is clean?鈥� he asks. 鈥淥il has been part of the natural environment for millions of years.鈥� For all practical purposes, he says, most environments recover relatively quickly, within 2 to 10 years. Those who make a living from the stocks of fish and other marine life off north-west Spain may disagree, but Kingston says an ecosystem has recovered when all parts of it are functioning again, not when the plant and animal populations return to previous levels.
But some toxicologists take a very different view, arguing that large oil spills can have an impact that lasts for decades. Ron Heintz, an oil spills specialist at the US government鈥檚 Auke Bay Laboratory in Alaska, has recently shown that minute amounts of polynuclear aromatic hydrocarbons (PAHs) in oil cause deformities in fish embryos that kill many of them before they reach adulthood. 鈥淥il pollution has much longer effects at much lower concentrations and with different compounds than we had thought,鈥� says Heintz.
The conventional view was that oil is only mildly toxic to fish. But that relied on studies of the short-term acute effects of compounds in oil such as benzene and toluene, which evaporate within a few days. It turns out that PAHs, which are released from oil over many decades, are the real poison.
鈥淥ur work has been replicated by others, but the oil industry still fails to acknowledge its validity,鈥� Heintz told 快猫短视频 this week.