Can temperature affect the release of ninhydrin-reactive nitrogen in gravesoil following the burial of a mammalian (Rattus rattus) cadaver?

Abstract

Although temperature and soil type are well known to influence the decomposition of organic resources, the effect of these variables on the release of ninhydrin-reactive nitrogen (NRN) of cadavers in soil has received little experimental investigation. To address this gap in knowledge, juvenile rat (Rattus rattus) cadavers were buried in one of three contrasting soils from tropical savanna ecosystems in Queensland, Australia and incubated at 29 °C, 22 °C or 15 °C in a laboratory setting. Cadaver burial resulted in a significant increase in NRN in all gravesoils to a concentration of approximately 15 μg/g soil greater than basal concentration of NRN. Peak levels were observed between 105 and 154 accumulated degree days. This effect was significantly affected by temperature, as gravesoils incubated at 15 °C were associated with a slower accumulation of NRN. No difference between soil types was observed. These findings have important implications for forensic taphonomy because they show the time at which NRN becomes an effective means to identify gravesoils and estimate early (1 to 2 days after death; ≤105 accumulated degree days) post-mortem interval.