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Authors: Lühe, Barbara von der
Title: The fate of human decomposition products in soils
Online publication date: 21-Jun-2016
Language: english
Abstract: During the decomposition of a human body, a variety of cadaveric lipids are introduced into the surrounding environment. The fate of cadaveric lipids in soils as well as the impact of soils on cadaver derived components is still poorly understood. Furthermore, the high diagnostic potential of lipids (Δ5-sterols, stanols, stanones, bile acids and fatty acids) and their long-lasting preservation in soils has been neglected in forensic research. Knowledge about the fate of human remains in soils can aid in selecting lipid biomarkers of human decomposition fluids and in understanding which soil abiotic and biotic factors regulate the decomposition of human remains in soils. For this purpose, a detailed assessment of the fate of cadaveric lipids was carried out. Soil samples were obtained from a case study where a body was found decomposing aboveground 11-18 days after deposition. Soil samples were taken 11-18 days after deposition and 358 days (one year) after removal of the body. The second soil sample set was obtained from putative mass graves (3 soil pits) from World War II, where 66 concentration camp prisoners were buried for 10 months (~late 1944-1945). Cadaveric lipids were determined in these soil samples after (I) testing suitable laboratory methods to determine (II) the concentration of Δ5-sterols, stanols, stanones, bile acids and fatty acids (III) to investigate the spatial distribution, transformation and degradation processes over time. The impact of soil biotic and abiotic parameters on decomposition was determined on adipocere from one individual. Minicontainers were used to assess decomposition of adipocere in undisturbed Calcisols and Arenosols. Recovery surrogates of Δ5-sterols and stanols were between 78-97% (R2=0.94-0.99) determined by standard addition on reference soil samples of the aboveground decomposition case study. 10-hydroxystearic acid, a typical fatty acid found in adipocere, was quantified with a precision of 97% by using effective carbon numbers (ECN) and relative standard response factors (SRF) by gas chromatography, because no analytical standard was available. In the surface decomposition study several tissue and faecal steroids (cholesterol, 5α-cholestanol, coprostanol, epicoprostanol, 5β-stigmastanol, epi-5β-stigmastanol and 5α-stigmastanol) and fatty acids (myristic acid, palmitic acid, oleic acid, stearic acid and 10-hydroxystearic acid) were detected in higher concentrations in soil beneath the body than in the reference. Cholesterol (0.5-400 µg gsoil-1) was the dominant steroid found beneath the thorax. Beneath the abdomen faecal steroids from the intestines predominated tissue steroids. Abundances of fatty acid salts and 10-hydroxystearic acid demonstrated potential anaerobic zones and adipocere formation beneath a decomposing body. After one year higher concentrations of fatty acids and steroids were still detected, but losses of total abundances were attributed to degradation and transformation processes. In the temporary mass graves faecal steroids and bile acids were indicative for human decomposition fluids in one of the three soil pits. Selected steroids (epicoprostanol, epi-5β-stigmastanol, isolithocholic acid) were unique for soil from the decomposition site. Cholesterol, 5α-cholestanol and 5α-cholestanone did not differ to the reference and were thus not suitable to indicate human decomposition fluids. Analysis of steroids revealed that at least one pit was likely used as mass grave, where human bodies were temporarily buried. In the minicontainer experiment, a decrease in adipocere abundances was found over time. In the Arenosol, more adipocere was degraded which was attributed to the sandy texture and the high air capacity. The clayey texture and influence of groundwater in the Calcisol hampered a rapid adipocere degradation. The study also showed that the loamy Calcisol, where macrofauna species were found, had an impact on adipocere metabolisation. In conclusion, combined analysis of Δ5-sterols, stanols, stanones, bile acids and fatty acids made it possible to track temporal pattern changes and processes involved in the fate of cadaveric lipids in soils. Selected lipids (steroids and bile acids) were suitable as indicators for decomposition fluids in soils, but the selection of lipids must always be adjusted to the specific forensic case. Furthermore, it has been shown that well aerated soils promote adipocere decomposition, which is important for decomposition rates at cemeteries to ensure a complete decomposition within the regular resting time.
DDC: 500 Naturwissenschaften
500 Natural sciences and mathematics
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 09 Chemie, Pharmazie u. Geowissensch.
Place: Mainz
Version: Original work
Publication type: Dissertation
License: in Copyright
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Extent: XVIII, 146 Seiten
Appears in collections:JGU-Publikationen

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