Application of multimolecular biomarker techniques to the identification of fecal material in archaeological soils and sediments

This paper focuses on the chemical analysis of organic residues in archaeological soils, particularly on the development and application of lipid ''biomarker'' techniques for the detection and characterization of disaggregated fecal matter. The work has been directed towards the study of soils from experimental and archaeological sites to assess the possibility of employing ''biomarkers'' characteristic of feces. Initial efforts in this area focused on building on the principle that 5 beta-stanols (which arise in feces from Delta(5)-stenols by microbial reduction in the gut) may be of use in assessing fecal inputs into archaeological soils and sediments. The analytical methods employed are based on the use of gas chromatography/mass spectrometry with selected ion monitoring (GC/MS-SIM) to provide a very sensitive and selective means of analyzing for the characteristic steroidal marker compounds. Enhanced selectivity can be achieved by use of GC/MS/MS employing selected reaction monitoring (SRM). The use of 5 beta-cholestan-3 beta-ol (coprostanol and its congeners) to identify the sites of ancient cesspits has been demonstrated. In an investigation of a set of soil samples taken at intervals across an experimental field only the variation in the concentration of 5 beta-stanols reflected manure addition, together with the dynamic effects of soil erosion and possibly bioterbation. This paper summarizes our recent findings in this area, placing special emphasis on developments in the use of multi-component mixtures of biomarkers, i.e., 5 beta-stanols and bile acids, to identify the origin of fecal inputs into soils with a high degree of specificity.