Tuesday, August 13, 2013

Soil sample specificity

In the medieval Danish town of Ribe, a youngster not more than 13 years old lay dying 800 years ago. By using a very specific soil sampling technique in the grave, chemist Kaare Lund Rasmussen of the University of Southern Denmark reveals what the sick child underwent within the last 2 days of life. A decaying body will release compounds into the soil which are later carried away by percolating groundwater, but when scientists localize an element in the immediate vicinity of the skeleton which is not normally found in the soil, they can make inferences that it came from the deceased. And when Rasmussen takes soil samples at the site of the lungs, liver, kidney, and upper arm muscles (NOTE THE HOLES IN THE IMAGE ABOVE), he can – based on the half-life of the element and how quickly it is excreted from a particular organ – develop a much more precise timeline than the bones would divulge. In this case, the child was administered mercury which, although highly toxic, has been used as the active ingredient in medicines since Roman times. It didn't help. And neither does knowing that they can't backtrack and reassess earlier burials based on this new technique. Rasmussen mourns, "Concerning past archaeological excavations it is appalling to think about all the soil that archaeologists have wheel barrowed away for more than a century – if we had samples of this soil, we would have access to a lot of important information."


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