Soil Changes from Exposure to Human Cadavers Over a One-Year Period

The focus of human decomposition studies has traditionally been on how external factors affect the decomposition of a body. There is much less literature on how the decomposition of a human cadaver affects its local ecosystem. This study attempts to address the knowledge gap in current literature regarding how the decomposition of human cadavers affects the bioavailability of essential plant nutrients (P, K, Ca, Fe, C and N) as well as toxins (As and Pb) in soil. By studying the bioavailability of plant nutrients, especially nitrogen, and toxins, this research hopes to inform new technologies and techniques for locating clandestine gravesites. The objectives of this study were twofold: 1) determine whether soils exposed to cadaveric decomposition can be visually distinguished from one another via macroscopic and microscopic observation and 2) observe general changes in nutrient and toxic element bioavailability and changes in carbon and nitrogen isotope ratios over time as well as spatially across a body. Visual analyses of soil samples, both macro- and microscopically did not show potential in distinguishing soil exposed to cadaver decomposition from unexposed soil. Relative bioavailability as well as overall bioavailable concentrations of both plant nutrients and toxins were highly elevated after 12 months. Toxins, such as As and Pb, tended to have greater bioavailable concentrations at the near-torso positions, though no consistent spatial trends between nutrient bioavailable concentrations were observed between the three individuals. Nitrogen concentrations and nitrogen isotope (δ15N) ratios show strong potential as markers of clandestine graves throughout the study period. While this research demonstrates further need to uncover what factors influence bioavailability of elements in gravesoil, it shows that the bioavailability of plant nutrients and toxins as well as δ15N ratios are greatly affected by cadaver decomposition, and emerging technologies in gravesite detection based on plant or soil changes have a solid foundation.