delta C-13 and delta D values of Opuntia atacamensis depending on different environmental conditions in the Atacama desert of Northern Chile

We analysed (13)carbon and deuterium discrimination in Opuntia atacamensis PHIL. at three different sites in the Atacama desert in Northern Chile: At the western Andean slopes, influenced by summer rainfall, in the very and C hilean central valley, and at coastal fog mountains. At the most and site, the central valley, discrimination of C-13 and D was less (8-values less negative) and also discrimination more against deuteriu m. This is an aridity, not an altitude effect. The differences in C-13 content may be due to some carbon fixation via the C3 photosynthetic pathway at the more humid sites. Deuterium enrichment at the and sites might be due to greater discrimination of HDO against H2O dur ing transpirational water loss.