August 10, 2013
Soil Analysis Provides Insight Of The Day Before A Person’s Death
redOrbit Staff & Wire Reports - Your Universe Online
Researchers from the University of Southern Denmark have developed a new method that can be used to provide a detailed look at the last day of a person’s life, according a study appearing in the journal Heritage Science.
Chemist Kaare Lund Rasmussen and his colleagues used their method to study the remains of a 10-13 year old child who had been buried in the medieval Danish town of Ribe approximately 800 years ago. They were able to determine the child had been given a large dose of mercury prior to passing away, most likely in an attempt to help cure a severe illness.
"I cannot say which diseases the child had contracted. But I can say that it was exposed to a large dose of mercury a couple of months before its death and again a day or two prior to death,” Rasmussen explained.
“You can imagine what happened: that the family for a while tried to cure the child with mercury containing medicine which may or may not have worked, but that the child's condition suddenly worsened and that it was administered a large dose of mercury which was, however, not able to save its life,” he added.
That insight was not gained by studying the child’s bones, the researchers said. Rather, the method used by Rasmussen’s team involved analysis of the soil surrounding the child’s resting place.
“When the body decays in the grave a lot of compounds are released to the surrounding soil – by far most of them organic compounds. Also, most of the inorganic elements are transformed to other compounds and later removed by the percolating groundwater throughout the centuries that follows,” Rasmussen said.
“If we can localize an element in the soil in the immediate vicinity of the skeleton which is not normally found in the soil itself, we can assume that it came from the deceased and this can tell us something about how the person lived,” he added. “We are not interested in death, but in the life before death.”
According to the researchers, mercury is of particular interest because it occurs rarely in normal soil but has been used by several different cultures worldwide throughout the years. As a result, it is occasionally found in archaeological excavations in a variety of locations, including Denmark. The authors explain mercury was used in medieval Europe in the color pigment cinnabar and as an ingredient in a variety of different medicines.
“Mercury is extremely toxic and surely some died from mercury poisoning and not the ailment it was meant to cure. Treatment with mercury was practiced well into the 1900's where, for instance, the Danish novelist Karen Blixen (Seven Gothic Tales) received treatment in 1914,” Rasmussen said. “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.”
In order to utilize the methods, the soil samples must be collected at the precise location of the original tissue, the researchers said. For example, in the area where a now completely decayed kidney had been positioned, the compounds that were originally part of the organ have since become part of the soil – provided it had not been washed away by groundwater.
“If there was mercury present in the kidney at the time of death it would have been transformed rapidly to mercury sulphide which is very immobile and undissolvable in water,” Rasmussen explained. “So in this way we can obtain information about the deceased even though we do not analyze the bones.”
In the case of the child from Ribe, the chemists joined forces with anthropologists in order to collect soil samples from the regions once occupied by the individual’s lungs, kidneys, liver and muscle tissue.
Due to the varying half-life of mercury between the different types of human tissue, they were able to determine that high concentrations of the substance had once been in the child’s lungs, suggesting he or she had been exposed to it within the last 48 hours prior to his or her death.
While bones can also be tested for excess mercury, Rasmussen explains the technique is limited. Where soil analysis can give insight into the last days and months of a person’s life, the bones can only provide information about mercury exposure dating from approximately three to 10 years before the death, he said.