On the styx bank - characterization of the headspace cadaveric volatiles released by submerged decaying rats

The cadaveric volatilome of terrestrial decomposition, including buried corpses, has been extensively studied in recent taphonomic research. However, there has been comparatively less attention given to the volatile organic compounds associated with submerged vertebrate remains. This decaying process is distinct, as evidenced by the succession of decay stages that significantly differ from terrestrial decomposition. Indeed, five stages can be delineated: fresh, early floating, floating decay, deterioration, and sunken remains. Due to the unique nature of underwater decomposition, we anticipate the release of different cadaveric volatiles from submerged remains. In this study, we characterize the volatile compounds emitted during underwater decomposition and that reach the surface. Rat cadavers were placed individually in glass chambers filled with water. The volatiles released at the surface were subsequently collected three times per week over the course of a month. Two types of water, fresh and marine, were used to assess the potential influence of the salinity level on the cadaveric volatilome. A total of 33 volatile compounds were identified, with the majority having previously been reported in the headspace of cadavers undergoing decomposition in a terrestrial environment. Among these compounds, those containing sulfur were the most abundant, with dimethyl disulfide being the major one. Our findings did not reveal any discernible impact of salinity levels on the volatile profile, which was, however, affected by the specific decaying stage. Notably, 3-methyl-indole emerged as a promising candidate for distinguishing between the first two stages of decomposition and the subsequent third stage.