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22 July 2004

A Window on the Environmental Sciences — Heidelberg Front Runner in the Analysis of Arctic Ice Samples

Heidelberg Environmental Sciences Work Show opened up a fascinating window on ongoing research in the field — and on the latest developments in the exploration of Arctic ice samples, a research area in which the Institute of Environmental Geochemistry of the University of Heidelberg has recently become the international front runner

In early July, the Heidelberg Institute of Environmental Geochemistry invited all interested to this year's Environmental Sciences Work Show, an event that was geared much more to general public interest than had previously been the case. A few days after the event, the organisers' assessment of the success of the Show was highly positive. The large variety of items on the programme opened up a fascinating window on the world of environmental science for everyone.

This is a research area where a great deal has been happening in recent years. It was thus only appropriate to entitle the event "What's New in the Environmental Sciences?" In the recent past the Institute of Environmental Geochemistry has made progress that has established Heidelberg as a global leader in such fields as the exploration of Arctic ice samples.

"This kind of success does not come of its own accord," emphasises Dr. Michael Krachler, one of the organisers of the Work Show. In his lecture he gave a brief overview of the effort involved in obtaining ice cores from the eternal ice of the Pole caps. "Obtaining these ice cores is a time-consuming and above all expensive undertaking," said Krachler. "To bore down into a glacier 15,000 feet above sea level, you not only have to have a base camp 9,000 feet up, you also need a well-trained team, the requisite equipment and lots and lots of luck with the weather. After that you have to get the ice core, which is several hundred yards long, back to civilisation unharmed."

The description of such feats in the interests of science naturally had a jaw-dropping effect on the audience breathlessly following the progress of the ice back to the lab. "When we get back, the first thing we have to do is to decontaminate the ice core from impurities caused by the bore fluid and the metal rub-off from the drill head." Teflon scrapers are used to carefully remove the outer layer of the core, as even the most infinitesimal impurities would distort the measuring results. "We can only do this in purified air labs of the kind used in the electronic chip industry."

Subsequently the ice is melted and stored in special flasks until the analysis proper begins. The analysis is done with one of the most sensitive measuring devices in existence. The machine in question costs some 500,000 euros and goes by the name of "high-resolution inductively coupled plasma mass spectrometer" (ICP-MS). There are only about 150 of these devices in academic research use anywhere in the world. But without the requisite infrastructure even the most sophisticated measuring device will not produce accurate results. "Luckily, in Heidelberg we have a top-quality purified air environment at our disposal that enables us to detect extremely low concentrations of elements, say, lead. The point is that the detection threshold is no longer determined by the sensitivity of the analysis equipment. Today such devices penetrate down into the sub-femtogram sphere, corresponding to less than a trillionth of a gram. No, it's the constant air purity in the lab that has become the clinching factor." Ultimately, impurities can never be ruled out entirely, so they at least have to be kept to a constant, extremely low level.

"Here in Heidelberg we have succeeded over the last few months in lowering the detection threshold by a factor of 10 for many trace elements," Michael Krachler enthuses. "That puts us out in the lead, internationally, although we've only been working on ice cores for about a year." One of the research aspects is the study of the proportion of lead in the atmosphere. The use of leaded fuels had caused this incidence to increase sharply since the 1940s, but with the advent of unleaded fuels it has now been declining again. These developments can be traced by studying the annual polar snowfall preserved in the glaciers. A record of the climatic fluctuations and emissions over thousands of years is inscribed in the eternal ice as if in some gigantic refrigerator.

"Of course, for such explorations we need to know what proportion of lead is 'normal', by which I mean the proportion stemming from natural sources," Michael Krachler explains. "Luckily we have another method enabling us to determine lead isotopes, which tell us like a finger-print whether the lead has originated from coal combustion, traffic or natural climatic processes."

So far, only one Australian research group has been in a position to do this, albeit on a maximum of ten samples per week. In Heidelberg, by contrast, four samples are analysed — every hour! "Also, we only require about a tenth of the sample amount, which is of course an immense advantage," enthuses Michael Krachler. "This puts us in a position to provide essential measurements — say, for climate model calculations — quicker and more effectively than any other institute." There could hardly be a clearer indication of the progress being made in the environmental sciences. And these developments have by no means come to a standstill. "Ultratrace analysis of ice cores from the High Arctic of Canada is just one example alongside many others. Reason enough to note the date of the next Environmental Sciences Work Show next term," suggests Michael Krachler with a smile. "The prospects are as exciting as ever!"
Heiko P. Wacker

Please address any inquiries to
Dr. Michael Krachler
Institute of Environmental Geochemistry
University of Heidelberg
Im Neuenheimer Feld 236
D-69120 Heidelberg
phone: 06221/544848, fax: 545228

Dr. Michael Schwarz
Press Officer of the University of Heidelberg
phone: 06221/542310, fax: 54317

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