Detection of structural degradation of porcine bone in different marine environments with Raman spectroscopy combined with chemometrics

The investigation of time since exposure and taphonomic alteration of bone in marine environments is crucial in forensic sciences. In this study, we explored the diagenetic changes to juvenile porcine bone in two different environmental marine contexts (submerged and intertidal) and how seasonal variation at time of deposition impacted on the pattern of taphonomic alteration in bone during early stages of exposure, from 6 to 24 weeks. The analysis was conducted using Raman spectroscopy combined with chemometrics. Principal component analysis of the Raman data of the recovered bones (either summer or winter season in 2014) showed that the main chemical changes occurred in the bioapatite (phosphate band, nu(1)(PO43-) at 961 cm(-1)) and organic constituents in the bones and depended on the exposure environment. Support vector machine (SVM) classification analysis classified the samples based on bone type, exposed environment and season, with high accuracy (>80%), but exposure time was less accurate (56%), although still higher than chance. When applying a SVM regression, time since exposure could be predicted with a +/- 5-week uncertainty. This study illustrated the potential and limitations of using Raman spectroscopy to detect structural degradation of bone in different marine environments for forensic purposes.