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RESEARCH INTERESTS
Ecology, environment, global change biology, stable isotopes, plant biology, SIRFER
Water in arid, riparian, and urban ecosystems
Biosphere - atmosphere gas exchange
Stable isotope fractionation processes
C3 and C4 photosynthesis
Forensic applications of stable isotopes
PUBLICATIONS
We are interested in ecological questions, particularly those that involve global change, land-use change, and urbanization issues. Our interests are in the understanding controls at the ecophysiological level and the scaling of these processes to ecosystem scales. We are also interested in how ecological information and an understanding of biochemical processes can be used in questions of forensic interest. Most of our research involves linking physiological or climatic processes with stable isotopes as an integrative tool. Our research focuses on four primary areas:
WATER We are examining the water fluxes and gas exchange in arid, riparian, and urban ecosystems of Utah. We are interested in understanding the dynamics of fluxes in theses ecosystems and the factors controlling those fluxes. Projects are underway along the Wasatch Front, the Salt Lake Valley, and southern Utah. Further details about specific projects can be found on the Ehleringer Lab home pages.
CO2 Physiological process during photosynthesis in aboveground vegetation and decomposition processes within the soil influence the rates of CO2 exchange between ecosystems and the air above them. As the magnitudes of these processes change and as these processes respond to environmental parameters, there are pronounced changes in the carbon and oxygen isotope ratios of the CO2 fluxing between the ecosystem and the atmosphere. We are interested in examining the controls of the isotopic composition of these fluxes and relating this information with carbon cycle and water cycle models. Understanding the sources and sinks of regional and global scale carbon cycles requires an understanding of how isotopic composition of the fluxes varies in both space and time. In effect, our studies focus on how physiological processes scale and influence regional and global carbon and oxygen isotope ratios of CO2 and water vapor in the atmosphere. Projects are underway along the Wasatch Front in Utah, the Salt Lake Valley, and at AmeriFlux sites in Colorado, Kansas, Maine, Massachusetts, Oregon, and Washington. Further details about specific projects can be found on the Ehleringer Lab home pages.
We are also involved in coordinating the efforts of other investigators in this area through the development of BASIN, an international network for the study of stable isotopes and biosphere-atmosphere gas exchange. Here the focus is on integrating efforts to get a better constraint on the magnitudes and dynamics of the carbon and trace gas cycles in different ecosystems globally.
ISOSCAPES We are interested in the geographic scaling of physiological and ecosystem processes that are recorded in the stable isotope ratios of specific molecules. Toward that goal we are developing models that allow us to take process-scale information and to incorporate that into spatial models that can be used to directly link with other spatial data sets. Using ArcGIS as a platform, we have been developing models to predict and identify variations in spatial patterns of stable isotopes in water, plants (leaves, seeds), animals (hair, protein, collagen, bones), and microbes. Further details about specific projects can be found on the Ehleringer Lab home pages.
FORENSICS Basic information about the natural variations in stable isotope composition gleaned from ecological and environmental studies can be used to source the origins of materials that are forensic interest. We focus on conducting the basic research critical to identifying which environmental signals might be recorded in materials of forensic interest. Such areas might include sourcing the origins of counterfeit currencies through the identification of the cellulose in paper, sourcing the origins of illicit drugs such as cocaine and heroin, and sourcing the origins of animals or animal products (such as ivory). Further details about specific projects can be found on the Ehleringer Lab home pages.
SIRFER We operate the Stable Isotope Ratio Facility for Environmental Research (SIRFER), an isotope ratio mass spectrometer facility that is open to all in the scientific community. Our facility consists of 7 isotope ratio mass spectrometers with the capacity to analyze virtually all biological and non-biological materials for their H, C, N, O, and S isotope ratios. This includes analyses of solid, aqueous, and gaseous samples. As supporting equipment, we have all of the critical off-line vacuum lines, a laser ablation system, GC, GC/MS, and HPLC instrumentation available.
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