Buried bone soil contamination

Figure 1. Ca and P concentrations in Egyptian bones. Key o, samples from mummies A, buried bones O and buried samples corrected for dilution by the organic component and soil contamination.

The contamination of archaeological bone samples by the soil will affect many of the trace elements. For example, the bones buried in the soil (Table I) contain substantially more Ti, Si, Ba, and V than most of the mummy samples. That the Cr concentrations correlate well with the Si02 content suggests that Cr concentrations can be used as a measure of soil contamination. Hancock et al. found that, when using INAA, the Mn, Al, and V levels seemed to be the most sensitive indicators of soil contamination (16). Whether these same elements will indicate the effects of deposition of mineral phases from solution is not clear. 

These results confirm the great difficulty in using buried bone samples in any type of trace element study. Even some of the mummy samples we studied were also contaminated. These results confirm that the analysis of the inorganic components of archaeological bone must be approached with great caution, especially when the bones have been in contact with soils or ground water solutions. Even isotopic studies may be affected by changes caused by recrystallization processes. 

Although there is an extensive literature on the chemical analysis of soil (J,2), very little work has been done on the dynamics of soil composition associated with buried bone. The elemental content of human bone has been related to the ancient diet (3). Any significant transfer of specific elements from bone to soil or vice versa would vitiate the analysis of bone in terms of diet. Loss of trace or minor elements from bone could result in build-up of the elements in soil directly adjacent to the bone, unless the newly introduced elements are flushed away by the action of groundwater. Similarly, transfer of contaminative elements from soil to bone could be associated with depletion of elements in soil directly adjacent to the bone, unless groundwater maintains an equilibrium by reintroduction of the depleted materials. Thus, establishment of enhancement or depletion in the soil of elements found in bone should be an important aspect in our understanding of the relationship between... 

While the inorganic matrix of human bones can survive, it can also be contaminated by the soil in which it was buried. Instrumental neutron activation analysis and X-ray fluorescence can be used to detect levels of contamination. Microscopic studies show that voids in the inorganic matrix can be filled with new mineral deposits that have resulted from diagenesis and contamination. 

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