Bone Molecular Modifications Induced by Diagenesis Followed-Up for 12 Months

SIMPLE SUMMARY: Improving knowledge about the mechanism of bone diagenesis is needed to help forensic investigators. Bone diagenesis refers to all processes (chemical or physical) that modify the chemical composition or the structure of skeletal remains. The mechanism of bone diagenesis is complex and poorly understood, especially at short timescales (between days and thousands of years). Identifying the chemical mechanism of diagenesis could help forensic investigators identify characteristics of skeletal remains, such as the sex, age or time elapsed since death. The aim of this work is to study bone diagenesis over 12 months on buried bone by Raman microspectroscopy. This technique allows for the evaluation of the chemical composition of bone. Human ribs from six individuals were buried for 12 months. The chemical composition of bone was analysed monthly by Raman microspectroscopy. The results showed that the mineral undergoes the dissolution–recrystallization mechanism. The collagen matrix of bone undergoes the hydrolysis mechanism. Hydrolysis induces the fragmentation of collagen by breaking the bonds that participate in the stability of collagen (cross-links). The results will help forensic investigators better understand the mechanism of bone diagenesis and the identification of skeletal remains. ABSTRACT: After death, diagenesis takes place. Numerous processes occur concomitantly, which makes it difficult to identify the diagenetic processes. The diagenetic processes refer to all processes (chemical or physical) that modify the skeletal remains. These processes are highly variable depending on the environmental factors (weather, temperature, age, sex, etc.), especially in the early stages. Numerous studies have evaluated bone diagenetic processes over long timescales (~millions of years), but fewer have been done over short timescales (between days and thousands of years). The objective of the study is to assess the early stages of diagenetic processes by Raman microspectroscopy over 12 months. The mineral and organic matrix modifications are monitored through physicochemical parameters. Ribs from six humans were buried in soil. The modifications of bone composition were followed by Raman spectroscopy each month. The decrease in the mineral/organic ratio and carbonate type-B content and the increase in crystallinity reveal that minerals undergo dissolution–recrystallization. The decrease in collagen cross-linking indicates that collagen hydrolysis induces the fragmentation of collagen fibres over 12 months.