Toxic legacy seeps from melting alpine glaciers: study
Thu Oct 15 02:31:12 EST 2009
Wed Oct 14 15:31:12 UTC 2009
GENEVA, Oct 14 AFP - Highly toxic pollutants absorbed by ice for decades are being released as Swiss glaciers melt under the impact of climate change, researchers have found.
They warned in a study abstract published in the journal Environmental Science and Technology that this could have a dire environmental impact on pristine areas as global warming accelerates.
Much of the pollution was dumped on the Swiss Alps by atmospheric currents, according to the researchers at three Swiss scientific institutes.
Their study of layers of sediment from an Alpine lake formed by a hydroelectric dam built in central Switzerland in 1953 revealed sharp build-ups of now banned chemical compounds from industry and farming, including dioxins and pesticides such as DDT.
"We can confirm with the help of these layers that, in the 1960s and 1970s, POPs (persistent organic pollutants) were produced in great quantities and were also deposited in this alpine lake," said one of the authors, Christian Bogdal, of the Swiss Federal Laboratory for Materials Testing and Research.
But while the concentration of POPs fell after the `70s as many of those compounds were banned, the scientists found an unusual resurgence in more recent sediment from the past 10 to 15 years.
They concluded that the lake, the Oberaarsee, was largely fed by water from a nearby melting glacier that was releasing pollutants at a level comparable to when the compounds were still in use.
"At this stage our study indicates that accelerated glacier melting due to global warming may also account for enhanced release of legacy organic pollutants at historically high levels," according to the full study.
The authors said in a statement that that it was the first time glaciers were demonstrated to be a secondary source of such pollution.
Production and use of POPs was banned or restricted under an international treaty in 2001, although several major industrialised nations such as the United States had started to outlaw them in preceding decades.
They are regarded as very durable and carcinogenic, and in some instances can be absorbed through the skin.
