Forensic taphonomy: processes associated with cadaver decomposition in soil

• Main Author: Carter, David O.
• Format: Thesis
• Language: unknown
• Published: 2005
• Subjects: Rattus rattus
• Online Access: https://researchonline.jcu.edu.au/1292/1/01front.pdf; https://researchonline.jcu.edu.au/1292/2/02whole.pdf

A series of laboratory and field incubations were carried out where juvenile rat (Rattus rattus) cadavers were buried in three soils of contrasting texture from tropical savanna ecosystems in Queensland, Australia. This work was done in order to develop an understanding of the effect of environmental variables (temperature, moisture), the soil in which a cadaver is buried and the nature of the cadaver on the processes associated with cadaver decomposition in soil. A pattern of mass loss comprised of an “Early Phase” of slow mass loss, “Intermediate Phase” of rapid mass loss and a “Late Phase” of slow mass loss. Early Phase decomposition coincided with an initial increase in carbon dioxide (CO2) evolution, microbial biomass carbon (Cmic), phosphodiesterase activity, protease activity and soil pH. Microbial activity was triggered within 24 hours of cadaver burial and this initial flush of activity was likely due to both soil-borne and cadaveric microbes. Intermediate Phase decomposition was typically associated with peak levels of CO2 evolution, Cmic, phosphodiesterase activity and soil pH. Late Phase decomposition typically coincided with a slowing down of process rates. In some cases, however, peak levels of protease activity were observed during late phase decomposition. The rate of cadaver decomposition increased with an increase in temperature and moisture. However, the rate of cadaver decomposition was slowed at a matric potential of –0.3 megapascals (MPa) in coarse-textured soil and a matric potential of –0.01 MPa in fine-textured soil. Temperature and moisture also had similar effects on CO2 evolution, Cmic, protease activity, phosphodiesterase activity and soil pH. In addition, the soil matrix and the soil microbial biomass had a significant effect on cadaver decomposition. The rate of cadaver decomposition following burial in soil was greater than when a cadaver was exposed to a sterile, soil-free environment. Furthermore, cadaver decomposition was greatest in sandy soil. These phenomena were likely due ...