Abstract
Chemical profiling of decomposition odour is conducted in the environmental sciences to detect malodourous target sources in air, water or soil. More recently decomposition odour profiling has been employed in the forensic sciences to generate a profile of the volatile organic compounds (VOCs) produced by decomposed remains. The chemical profile of decomposition odour is still being debated with variations in the VOC profile attributed to the sample collection technique, method of chemical analysis, and environment in which decomposition occurred. To date, little consideration has been given to the partitioning of odour between different matrices and the impact this has on developing an accurate VOC profile. The purpose of this research was to investigate the decomposition odour profile surrounding vertebrate carrion to determine how VOCs partition between soil and air. Four pig carcasses (Sus scrofa domesticus L.) were placed on a soil surface to decompose naturally and their odour profile monitored over a period of two months. Corresponding control sites were also monitored to determine the VOC profile of the surrounding environment. Samples were collected from the soil below and the air (headspace) above the decomposed remains using sorbent tubes and analysed using gas chromatography-mass spectrometry. A total of 249 compounds were identified but only 58 compounds were common to both air and soil samples. This study has demonstrated that soil and air samples produce distinct subsets of VOCs that contribute to the overall decomposition odour. Sample collection from only one matrix will reduce the likelihood of detecting the complete spectrum of VOCs, which further confounds the issue of determining a complete and accurate decomposition odour profile. Confirmation of this profile will enhance the performance of cadaver-detection dogs that are tasked with detecting decomposition odour in both soil and air to locate victim remains.
Highlights
The decomposition of organic matter is a complex series of chemical reactions primarily driven by microbial enzymes
Carcasses were characterised as being in the fresh stage from day 0 to day 1 (ADD 24.40)
On day 14 (ADD 340.85), all carcasses were characterised as being in the advanced decay stage with extensive mummification
Summary
The decomposition of organic matter is a complex series of chemical reactions primarily driven by microbial enzymes. These reactions result in the production of volatile organic compounds (VOCs) as by-products that are subsequently released into the surrounding environment [1,2,3]. Their dispersal is ensured by their physicochemical properties, i.e. low molecular weight, high vapour pressure, and low boiling point [4]. Decomposition odour has been investigated in the forensic sciences to determine the key compounds used by flies and beetles [2,14,15,16,17] and canines [3,18,19,20,21,22] to locate the target source of the odour (i.e. carrion or human remains)
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