Delta-C-13

The ratio of carbon-13 to carbon-12 in a biological sample, expressed relative to a standard (VPDB). Distinguishes C3 plant diets (wheat, rice; delta-C-13 around -25 per mil) from C4 plant diets (maize, millet; delta-C-13 around -12 per mil). Used in forensic provenance to distinguish dietary traditions associated with different agricultural regions.