Stable carbon and nitrogen isotope variations in soils: forensic applications

Abstract

Abstract A study has been undertaken to assess the significance of carbon and nitrogen content and stable isotopic variation in soils in relation to their practical use as a tool in forensic soil investigations. It forms part of a wider study to assess a range of techniques in a forensic context. Carbon and nitrogen abundance and δ 13 C and δ 15 N values have been determined in soil samples from six locations, using continuous flow-isotopic ratio mass spectrometry, to quantify: (1) stability over short time periods up to 2 years, (2) variation over short-scale distances, and (3) variability during primary transfer and mixing. Over a 2-year time period, variation was found to be largest in the elemental abundance, with the isotopic ratios being more stable. Used in combination, stable isotope analysis can be diagnostic and useful for discriminating between sites. No statistically significant differences at the 95% confidence level (using analysis of variance, ANOVA) were found for one-stage primary transfer in three of the four soils tested; the fourth sediment from an estuarine environment did show statistically significant difference at the 95% confidence level.