Large image view: Tracing marijuana to its roots
![[Photo: Read caption below]](/news/archives/news-archives-2002-2010/featured/07/marijuana/images/zoom/howe1.jpg)
ÃÛÌÒÓ°Ïñ photo by Marmian Grimes
Tim Howe holds a water sample tray for the autosampler on the thermal conversion elemental analyzer. The analyzer prepares samples for analysis in a stable isotope ratio mass spectrometer.