An Isotope Ratio Mass Spectrometer for the Biological Sciences at the University of Arizona

University Of Arizona, Tucson AZ

Investigators

Abstract

Stable isotope ratio mass spectrometry is a fundamental tool used to study energy and nutrient flow, metabolism, and physiology in natural and human-dominated ecosystems. Stable isotopes of the light elements (C, H, N, O, and S) occur naturally at different abundances among organic and inorganic molecules cycling within the biosphere. Isotopes within these molecules tend to separate between product and reactant in biochemical reactions and during diffusional flux across concentration gradients, leaving a characteristic fingerprint of these processes on ecosystems. Thus, stable isotopes contain information on physical, biophysical, and biological processes that govern the fate of materials in Earth's ecosystems. Stable isotope measurements offer unique insights into physiological variation, integrating processes at different spatial and temporal scales. Measurements of stable isotope ratios in soils and plant samples are used to reconstruct past climates and vegetation distribution, evaluate physiological responses of wild and domesticated plants and animals to environmental stress, characterize patterns of material transfers and transformations among plant, animal, and microbial components of ecosystems, and understand atmosphere-biosphere interactions. Stable isotope measurements offer great promise for evaluating responses of Earth's ecosystems to human activities at the global level. A continuous-flow isotope ratio mass spectrometer equipped with automated peripherals for sample-preparation and analysis from Finnigan MAT will be used for studies in ecosystem ecology, plant and animal physiological ecology, evolutionary ecology and global change biology. The new mass spectrometer system will greatly enhance undergraduate, graduate, and post-doctoral education at the University of Arizona. The five major users collectively advise 13 graduate students, 16 undergraduate students, and 4 post-docs, all of whom will use the mass spectrometer. At least six formal University of Arizona courses cover stable isotope theory and/or methodology. This new mass spectrometer system will ensure that the University of Arizona has the technological capability to meet research and teaching challenges well into the future.