Jessica Hamzelou, New Scientist 9 Oct 09;
Bad hair and shoulder pads are not the only things from the 1980s that we'd rather not see again. Nasty chemicals banned in that decade are also on the list. Unfortunately, melting Alpine glaciers are generating a revival of toxic organic pollutants.
Christian Bogdal and colleagues at the Swiss Federal Institute of Technology in Zurich studied levels of pollution in sediment at the bottom of the Oberaar lake in Bern, Switzerland.
The flow of pollutants into the lake peaked in the 1970s, mainly due to the production of plastics, electronics, pesticides and fragrances. The levels declined during the 1980s and 1990s when people realised that these compounds were toxic and they were banned.
However, they found that banned chemicals, such as pesticides that have been linked with Parkinson's disease, have been pouring into the lake at an increasing rate since the 1990s.
Powerless observers
Bogdal reckons that a glacier feeding the lake has been storing these chemicals for decades, and is releasing them as it melts. This process could be dramatically sped up by global warming, he warns.
The problem isn't limited to Alpine glaciers. Since these chemicals would have been transported great distances via the atmosphere before they were frozen into ice, many other glaciers around the world may be contaminated. Toxic chemicals have previously been found in polar regions - putting arctic wildlife at risk.
There is little we can do about it, however. "Stopping global warming could slow the melting of glaciers, but the chemicals will still be released eventually," says Bogdal.
Many toxic chemicals are still used in plastics and electronic equipment, such as brominated flame retardants. Bogdal warns that these could represent the next generation's problem: "They are deposited on glaciers today and will reappear in our lakes in a few decades."
Journal reference: Environmental Science & Technology, DOI: 10.1021/es901628x
'Toxic legacy' seeps from melting Alpine glaciers
Yahoo News 14 Oct 09;
GENEVA (AFP) – Swiss researchers have found that Alpine glaciers melting under the impact of climate change are releasing highly toxic pollutants that had been absorbed by the ice for decades.
They warned in a study abstract published in the journal Environmental Science and Technology that it could have a "dire environmental impact" on "pristine mountain areas" as global warming accelerates.
Much of the pollution was dumped on Europe's biggest mountain range by atmospheric currents from further afield, 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 like DDT.
"We can confirm with the help of these layers that, in the 1960s and 1970s, POPs (Persistant 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 1970s 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.
One of the scientists, Peter Schmid, told AFP on Wednesday that their findings were replicated at two other glacial lakes in the Swiss Alps.
But another lake that was not fed by glaciers did not show any increase in the compounds.
The authors said that that it was the first time that 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.
Their release in an Alpine setting could lead to "short but intense pulses" of pollution in spring and summer, the scientists concluded.
That could affect drinking water in Alpine huts, the food chain through fish from nearby lakes, irrigation facilities and even artificial snow on ski slopes.
The Alps are commonly known as the water tower of Europe, as the source of major rivers such as the Rhine and Rhone.
Schmid cautioned that more research was needed to determine the pathways of the POPs in the Alps and how much they retained their toxicity.
