Resumen de The stable isotope ratios of marijuana: II.Strontium isotopes relate to geographic origin

Jason B. West, Janet M. Hurley, Francis Ö Dudás, James R. Ehleringer

• Effectively addressing marijuana trade is aided by understanding marijuana geographic sources. We analyzed the87Sr ⁄86Sr of mar-ijuana samples grown in 79 counties across the United States to determine if a primary geologic signal is retained in marijuana, which could thereforebe useful for geographic sourcing. The marijuana results were compared with modeled bedrock87Sr ⁄86Sr values based on87Rb decay rates and ageneralized geologic map of the U.S.A. A significant correlation was observed between marijuana87Sr ⁄86Sr and modeled bedrock87Sr ⁄86Sr.Although values clustered near the 1:1 relationship, there was a predominance of positive anomalies, perhaps attributable to carbonate bedrock. Asmall number of negative anomalies were also observed, which were generally associated with granitic bedrocks. These results suggest that strontiumisotopes in marijuana record the geographic origins of marijuana, and that refinement of the base strontium map (or strontium isoscape) and improvedunderstanding of other strontium sources would be productive