Investigation of sterols as potential biomarkers for the detection of pig (S. s. domesticus) decomposition fluid in soils § Barbara von der Lu ¨ he a, *, Lorna A. Dawson b , Robert W. Mayes b , Shari L. Forbes c , Sabine Fiedler a a Soil Sciences, Department of Geography, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher Weg 21, 55099 Mainz, Germany b The James Hutton Institute, Macaulay Drive, Craigiebuckler, Aberdeen AB15 8QH, UK c Centre of Forensic Science, University of Technology, PO Box 123, Broadway, Sydney, NSW 2007, Australia 1. Introduction Sterols are natural compounds with a characteristic tetracyclic ring structure and belong to the group of lipids. They are divided due to their origin into phytosterols (e.g. b-sitosterol), mycosterols (e.g. ergosterol) and zoosterols e.g. cholesterol and coprostanol [1]. Cholesterol (cholest-5-en-3b-ol) is an ubiquitous component of all animal cells (Table 1) but is present in trace levels only in plants which have other common sterols (e.g. b-sitosterol, stigmasterol) [2–5]. It is synthesised by extraheptic tissues in the liver and performs essential functions as a component of plasma mem- branes and in lipid metabolism [2,4,5]. Coprostanol (5b-cholestan- 3b-ol) is formed in the intestinal tract of higher mammals as a microbial hydrogenation product of cholesterol [6]. In recent studies, zoosterols and phytosterols have been investigated as pollution biomarkers introduced to marine and terrestrial environments or as faecal markers for archeological applications [7]. Notably, coprostanol is considered a useful marker associated with the faeces of carnivores and omnivores, including pigs and humans [6]. In a study by Bethell et al. [8], coprostanol was used as a marker to detect the presence of faecal material in archaeological soils, for example from ancient latrine sites [8] demonstrating its persistence against microbial degradation. In forensic investiga- tions degradation products of human remains are of interest because they could be used to detect the presence of decomposing human remains in soils (e.g. clandestine graves). After death the decomposition of human remains is followed by the release of decomposition fluid into the environment where the body is exposed, for example soil. The degradation of cadavers above and below the soil surface has been investigated in several studies focusing on a variety of potential component markers. Fiedler et al. [9] analysed depth profiles of organic carbon and phosphorus to locate the original site of a former mass grave. Carter et al. [10] detected amino acids in soil samples with the application of ninhydrin-reactive nitrogen in order to relocate body parts of a human cadaver which had been scavenged from its original Forensic Science International 230 (2013) 68–73 A R T I C L E I N F O Article history: Available online 11 April 2013 Keywords: Grave soil Coprostanol Cholesterol b-sitosterol Grave markers A B S T R A C T This study was carried out to evaluate the potential of using cholesterol and coprostanol, as indicators for the detection of decomposition fluid of buried pigs (S. s. domesticus) in soils. In May 2007, four pig carcasses (35 kg) were buried in shallow graves (40 cm depth) at the University of Ontario Institute of Technology in Canada. Two pigs were exhumed after three months (Pig 1, Pig 2) and six months (Pig 3, Pig 4) post burial. Soil samples were collected beneath the pig carcasses (40 cm depth) and from grave walls (15–20 cm depth) as well as from a parallel control site. Coprostanol and cholesterol were extracted from soils, purified with solid phase extraction (SPE) and analysed with gas chromatography/ mass spectrometry (GC/MS). A significant increase in cholesterol concentrations (p < 0.05) and amounts of coprostanol were detected in soil located beneath the pig carcasses after three months of burial. It is assumed that during the putrefaction and liquefaction stages of decomposition pig fluid which contains cholesterol and coprostanol is released into the underlying soil. Therefore, cholesterol and coprostanol could be used as potential biomarkers to detect the presence of decomposition fluid three months after burial under comparable soil and environmental conditions. Further research is suggested for additional soil sampling before and after three months to investigate the abundance of these and other sterols. ß 2013 Elsevier Ireland Ltd. All rights reserved. § This paper is part of the special issue entitled: 6th European Academy of Forensic Science Conference (EAFS 2012), Guest-edited by Didier Meuwly. * Corresponding author at: Soil Sciences, Department of Geography, Johannes- Gutenberg-University Mainz, Johann-Joachim-Becher Weg 21, 55099 Mainz, Germany. Tel.: +49 6131 3920947; fax: +49 6131 3924735. E-mail addresses: B.vonderluehe@geo.uni-mainz.de (B. von der Lu ¨ he), Lorna.Dawson@hutton.ac.uk (L.A. Dawson), Robert.Mayes@hutton.ac.uk (R.W. Mayes), shari.forbes@uts.edu.au (S.L. Forbes), S.Fiedler@geo.uni-mainz.de (S. Fiedler). Contents lists available at SciVerse ScienceDirect Forensic Science International jou r nal h o mep age: w ww.els evier .co m/lo c ate/fo r sc iin t 0379-0738/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.forsciint.2013.03.030