Evaluation of Soil Chemistry in Human Decomposition Sites
Fancher, James P.
Soil samples were analyzed from cadaver decomposition islands (CDI) of 63 human decomposition sites at the Forensic Anthropology Research Facility (FARF), Texas State University, in order to develop a method to estimate the postmortem interval (PMI) for each donation from these data. An additional 5 control site samples were also analyzed to establish a baseline record of undisturbed soils. Fifteen soil parameters were measured or calculated that included pH, electroconductivity, nitrate-N, ammonium-N, total dissolved nitrogen, dissolved organic nitrogen, orthophosphate-P, organic carbon, inorganic carbon, total carbon, sodium, potassium, magnesium, calcium and carbon/nitrogen ratio. Accumulated Degree Days (ADD) at a base temperature of 4°C (ADD_4) were also calculated for each donation. The data were analyzed using multiple regression with PMI and ADD_4 as the dependent variables and the soil parameters as independent variables. Regression formulae for 13 models were run that had R squared values ranging from 0.60 to 0.98 All of the models were statistically significant. The regression formulae results for ADD_4 were similar to PMI, indicating that ADD_4 may be used as a surrogate for estimating PMI. Measures of soil parameters derived from predator and microbial mediated decomposition of human remains show promise in estimating PMI accurately for a period up to nearly 5 years at FARF. This persistent change in soil chemistry extends the ability to estimate PMI in consort with the traditional methods of entomology and forensic anthropology in support of medical-legal investigations, humanitarian recovery efforts, and criminal and civil cases. This project has also recorded a baseline soil analysis for a new human decomposition research site.
Human decomposition, Soil analysis, Taphonomy, Forensic Anthropology
Fancher, J. P. (2015). <i>Evaluation of soil chemistry in human decomposition sites</i> (Unpublished thesis). Texas State University, San Marcos, Texas.