Pit for analyzing Freon presence

• Language: unknown
• Subjects: Antarctic; Greenland; Rasmussen; South Pole; The Antarctic; Antarc*; Ice cap; South pole
• Online Access: http://cdm16786.contentdm.oclc.org:80/cdm/ref/collection/antartica/id/55

One of the projects Dr. Rasmussen and I decided to do was to dig a pit in the snow approximately 200 meters away from the South Pole station in a clean area and to go down into this pit and mark yearly layers of accumulation of the snow and ice. And what we would do is take horizontal samples using an auger. These would give us a round core approximately 6 inches in diameter and about a meter long. And that core would then be taken, sealed into a container. It could then be melted and the freons that were trapped in that ice would then be released, and we could then analyze them by gas chromatography. The purpose of doing this experiment was that at this time in 1973, there was a number of people in the literature who claimed that freons were actually natural products and not man-made at all. And this was directly against what most chemists knew, but we decided, since we were at the South Pole, to go ahead and dig a pit. And we could actually go back close to 60 years, and that was definitely before freons were produced, because they were made in the mid-1930’s by Dupont. And so we were able to dig down, and at this point, where we are in this pit is approximately 1920. So we’re down before freons should’ve been produced, and what we found in these ice cores is absolutely no amount of freons present whatsoever. There was nothing there. And so it was direct evidence, and it was published in the literature that freons were totally man-made and only produced starting in the 1930’s. There was no sign of anything in the Antarctic ice frozen in. By the way, as a side note, the Antarctic ice contained large amounts of freons. Part of the thing is it forms what we call a clathrate compound with ice, where the Freon molecules go into the open cages of the ice crystal and will be held there. And so the concentrations in the ice itself were many times what it would be if it was just in the air itself that was trapped. In fact, freons were actually concentrated in the Antarctic ice. We estimated by the measurements that we made that probably half the freons to a third of the freons ever produced were all stored in the Antarctic ice cap and probably a similar amount in the Greenland ice cap. So that if these were ever to melt, we would have a huge release of freons back to the atmosphere. So a large amount of the freons that disappeared from the atmosphere are now located in the ice regions of the Greenland and Antarctic continents. As a note, you can see the yearly accumulation layers by these little red material markers in the snow. What we did is we found an old pair of long johns that were red and we tore them in little strips and kind of pinned them up so that we could take pictures and show the yearly accumulation layers. And we would then work our way down, and we could count and that way get an estimate of the age of the sample that we were taking. As a further note on these accumulation lines that we were indicating: why we could see them is very simple. During the Antarctic summer, we have very little ice crystal precipitation. Most of that occurs during the winter, and you have the sun shining down on the snow fairly intensely. And what that does is it sublimes a lot of the surface snow off, and it creates a layer that is more of an ice layer that has been somewhat sublimed and melted. And so you can easily pick that up and see it when you dig a pit down and carefully scrape off the side of the area going down. And you can pick up and identify yearly layers quite easily. This can be done going back at least to the late 1800’s. That’s as far as we dug back, but we could do that quite easily, probably 100 years.