Necrosols characterization in the dry tropical forest in Colombia: an approach from forensic geology

Abstract

Necrosols are soils related to burials, as inhumation conditions produce particular changes in their environment. Consequently, this study using forensic geoscience techniques makes it possible to maximize the effective search for clandestine burials. This constitutes a discipline with few academic initiatives in Latin America. The investigation of our project arose from exhumations of three rural cemeteries that took place when changes in land use of the Ituango hydroelectric project in the Cauca river canyon in Colombia, flooded the communities. During the exhumation process, the description and sampling of the profiles within the 3 cemeteries was carried out. Likewise, natural profiles were described and sampled in the surroundings of 2 out of 3 cemeteries, to determine the variations of the micromorphological and chemical properties resulting from the effect of the burials. The soil samples were analyzed with chemical and micromorphological methods. The study objective was the identification of differences between the natural and intervened soils, in order to propose features and pedo-anthropogenic processes that characterize the studied Necrosols. The results show clear differences between the cemetery soils, with respect to their natural counterparts. In consequence we found coffin wood and bone microfragments, minerals with parallel orientations, and high concentration of roots at the burial level and pedogenic aggregates mixtures incorporated into non-pedogenic matrix. From the chemical point of view, the Necrosols compared to natural soils, show highest concentration of S, mobile Fe, P, in addition to the increase of the soil cation exchange capacity. The present study demonstrated the usefulness of micromorphology as a powerful tool in confirming the presence of Necrosols with methods used in forensic archeology and geoscience. In accordance with the objective set out in this work, it was possible to characterize particular micromorphological and chemical properties in Necrosols to determine pedo-anthropogenic features and processes. The observed results in the Necrosols of three cemeteries in the tropical dry forest in Colombia could be proposed as model diagnostic features for the identification of clandestine burials; particularly for areas that meet similar pedological, geomorphological, and bioclimatic contexts. This could be useful in forensic geoscience.