Banned chemical travels across three oceans

03/16/04

A chemical once used in pesticides in Asia has accumulated thousands of miles away in Canada, according to a University of Toronto study.

High concentrations of alpha-hexachlorocyclohexane (HCH) were detected in the atmosphere of Sable Island off the coast of Nova Scotia and Newfoundland, says Professor Frank Wania of chemistry. The chemical was last used about 15 years ago in countries such as China and India but followed atmospheric and water flows across the Pacific, Arctic and Atlantic oceans to end up in eastern Canada. Frigid northern temperatures slowed its evaporation and degradation rate and trapped the chemical until it hit warmer waters where it will eventually evaporate.

"The Arctic Ocean has a 'lid' on top in form of an ice cover," says Wania. "Over the last 20 years it acted as a sort of refrigerator preserving the chemical that is now flowing into Atlantic Canada."

In the study, Wania and his team established a network of air sampling stations on a north-south route from the Arctic to Central America and east-west from Newfoundland to Vancouver Island. The sampling stations consist of polymer resins pellets of a lightweight plastic material that absorb pollutants like a sponge, allowing researchers to monitor alpha-HCH and other chemicals across the continent.

Source: Eurekalert & others

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