Spurenelementuntersuchungen an bodengelagertem Skelettmaterial

Abstract

Analysis of trace elements in human bone have been established for the reconstruction of paleodietary patterns of historic populations. A prerequisite for the interpretation of trace elements concentration derived from buried human bone has to be that the data obtained represents in vivo element concentrations. However, change of concentration due to diagenetic processes after burial can not be excluded.For the elements barium and strontium systematic concentration increase in the bone mineral are described obviously caused by diagenetic processes during burial.Widely established protocols which are assumed to reliably remove possible entry of elements in the bone mineral were tested. None of these methods proved to be able to effectively remove all traces of post-burial element uptake in the bone. Especially the chemical removal of contaminants a method generally accepted in trace element studies has to considered as inadequate.Since diagenetic concentration changes can be identified for nutritional trace elements and by the fact that these alterations - ultimately leading to incorrect interpretation of data - appear to be irreversible, a thorough analysis and characterization of diagenetic changes seemed necessary.Evaluation of diagenetic changes was carried out based on chemical properties of the native bone mineral which served as control criterion. However, according to the results of these analysis the mentioned control variables can at best only be used as an estimation for the possible presence of diagenetic changes. A distinct quantification of diagenetically related changes in concentration needed to reconstruct the element content in vivo is not feasible due to the high complexity and variability of interaction between bone and soil chemistry.Comparison of concentration between various bone samples as well as the microanalytical analysis of a single sample were carried out to broaden the understanding of diagenetically caused alteration of bone mineral. Caused by the variable state of preservation of the bone mineral typical patterns of element distribution in the bone were distinguishable. Both the results of the microanalysis and the bulk analysis of bone samples were interpreted together. Based on these results a discussion of explanations on diagenetically caused alteration in element concentration given in the literature is following. Main point of interest is the cause for the inefficiency of the widely accepted method of chemical removal of contaminants.Independently of the problem of diagenesis the distribution and variability of the element strontium in bone mineral was analysed as an additional point. For strontium a systematic distribution in a compact femoral shaft was determined. The results of the analysis give evidence that strontium is not incorporated homogeneously in the bone area. This can be seen as a further problem for the interpretation of strontium concentration data used for the reconstruction of paleodietary patterns.