Oxygen and Hydrogen Isotopes in Fruit and Vegetable Juices

Abstract
18O/16O ratios from the juices of a number of fruits and vegetables were measured and found to be isotopically more enriched than the water in which they grew. Fast-growing high-water-content vegetables exhibited less enrichment than slower growing fruits such as apples, pears and plums. 18O/16O measurements were also made on the water from various sections of several plants, and the enrichment occurred in the following order: leaves > fruit > stem .gtoreq. ground water. D[deuterium]/H and 18O/16O measurements were made on a series of grape juice samples and, when plotted against each other, gave a slope of 3.9, indicating that the physical process causing this enrichment was probably evaporation, i.e., evapotranspiration.