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Dean Atkinson

Associate Professor of Chemistry

Ph.D., 1995, Physical Chemistry, University of Arizona

Analytical/Physical Chemistry; Atmospheric & Environmental Chemistry and Physics

The Atkinson research group is involved in the development and application of new instruments that measure the optical properties of atmospheric aerosols. Aerosols (particles suspended in air) and their impact on clouds are currently the largest contributors to the uncertainty of global climate models. Particles have both direct and indirect radiative effects; some particle types cool the planet by "bouncing" radiation back out into space, while others (black carbon) warm the atmosphere when they absorb sunlight, and both types can have more subtle effects through their interaction with clouds. Since clouds are the largest negative feedback working against global warming, aerosol-cloud interactions are very important and are currently poorly characterized in global climate models. The Atkinson group has been using a cavity ring-down (CRD) based instrument (and other instruments) to measure the key aerosol optical properties extinction, scattering, absorption, and single scattering albedo at ground level for the last decade. An example of this work in a "real world" setting is the Carbonaceous Aerosols and Radiative Effects Study (CARES), a DOE sponsored field intensive experiment that was conducted in June of 2010 in and near Sacramento, CA. Dr. Atkinson deployed two of his CRD extinction instruments and a newly developed type of nephelometer during the study to characterize the optical properties and evolution of the aerosol as it was transported across the Sacramento Valley, after having (presumably) been produced by transportation pollution in Sacramento or the Bay area. An attempt to simulate one effect of clouds on the aerosols is made by varying the relative humidity in Dr. Atkinson's newest variant of the CRD instrument, which is also designed for airborne applications. The Atkinson group also uses these instruments in more controlled "laboratory" settings to characterize likely aerosol sources like diesel and biodiesel combustion sources.

Kelley Barsanti

Research Assistant Professor, Civil and Environmental Engineering

Ph.D., 2006, Environmental Science and Engineering, Oregon Health & Sciences University, Portland

Atmospheric Particulate Matter (Aerosol) Modeling; Air Quality-Climate Interactions

Dr. Barsanti's research pursuits are in modeling atmospheric particulate matter (PM) which is a key contributor to air pollution and climate change. More specifically, she is interested in using knowledge gained from process-level models and experiments to better represent PM formation and loss in models of regional and global air quality and climate. Her current research includes developing a new secondary organic aerosol model approach for use in regional and global chemical transport models and developing parameterizations of primary and secondary organic aerosol formation from biogenic emissions. Dr. Barsanti has published articles in Atmospheric Chemistry and Physics, Atmospheric Environment, and Proceedings of the National Academy of Sciences. In addition to pursuing independent research and teaching, she is serving as the managing director of the Center for Climate and Aerosol Research. Dr. Barsanti came to Portland State University following three years at the National Center for Atmospheric Research where she was an Advanced Study Program Postdoctoral Fellow.

Chris Butenhoff

Assistant Professor of Physics

PhD, 2010, Applied Physics, Portland State University

Portland, OR

Greenhouse Gas/Biogenic Emissions; Human and Climate Impacts on Land Use and Emissions; Biogeochemical Modeling

Dr. Butenhoff's research has focused on understanding the changing budgets of global trace gases such as methane, nitrous oxide, carbon monoxide, hydrogen, and more ozone-depleting compounds like the fluorocarbons. Budgets are determined by a mix of production, transport, and removal processes; Dr. Butenhoff studies all three components. He and coworkers have made considerable progress, through modeling and measurements, understanding some of these changes and putting constraints on global fluxes. They have developed simple transport and biogeochemical models that have been used to examine questions related to greenhouse gas emissions from agriculture and biomass burning, oxidation processes in the atmosphere, and variability of emissions across spatial and temporal scales.

Future progress in this field requires the synthesis of surface measurements and space-based observations of land use and vegetation, along with terrestrial biogeochemistry, atmospheric chemistry, and climate models. With the coupling of these resources at the appropriate time and space scales a range of questions can be addressed, including what are the impacts of climate change on trace gas emissions at regional to global scales, how will climate-shifting vegetation zones change patterns of emissions, how will changing hydrology influence timing and magnitudes of emissions, and many others. Dr. Butenhoff plans to use existing models when possible, develop or improve models when needed, and create novel spatially-gridded maps of model drivers like biophysical vegetation parameters and land use practices such as agricultural management. Many of the important model drivers are unknown at relevant spatial and temporal scales and will require integration of data sets across disciplines to develop. As an example, the human dimension of agriculture in broad stroke is known but not at spatial scales appropriate for process level models. Improving the input information needed to drive these models will lead to better estimates of future emissions.

Linda George

Professor, Environmental Science and Management, School of the Environment

PhD, 1991, ESR/Chemistry, Portland State University

Atmospheric Chemistry; Urban Air Pollution

The George research group focuses on the measurement and modeling of urban air quality as a means of improving understanding of human exposure to urban air pollutants. Currently, the understanding of human exposure is limited by the inability of airshed models to accurately assess pollutant levels at the local scale. The George group is working to improve spatial resolution to the local scale (< 1km) air quality using new statistical modeling approaches that incorporate neighborhood scale measurements (top-down modeling). They are also working on developing new monitoring techniques that could cost-effectively assess air quality at the neighborhood scale (using nanomaterials). Ultimately, this approach to modeling and monitoring will allow Dr. George and coworkers to spatially resolve the impact of changing emissions, land-use patterns and climate on sub-populations within an urban environment.

The George group also is interested in the role of vegetation in urban air quality. Trees are known to be a source of emissions (biogenic hydrocarbons), as well as play a role in cleansing the air through air to leaf deposition. Dr. George and coworkers are currently investigating biogenic emissions generated from Forest Park and the formation of secondary aerosols through the reaction of biogenics with nitrate radical.

Aslam Khalil

Professor of Physics

Ph.D., 1976, Physics, University of Texas, Austin

Ph.D., 1979, Environmental Science, Oregon Graduate Center

Atmospheric Trace Gases

The Khalil group's major work is on the emissions of non-CO2 greenhouse gases from man-made sources. Specifically they are working on the emissions of methane and nitrous oxide from rice agriculture, which is a major anthropogenic source of both. They study the mechanics of how methane is formed, transported, oxidized and emitted to the atmosphere. This information is necessary to evaluate country-wide and global emission rates and to devise methods of controlling emissions. This work involves controlled experiments in a greenhouse on campus at PSU, field studies in the rice fields of China and theoretical models to connect and quantify the processes.

Jim Pankow

Professor of Chemistry and Civil & Environmental Engineering

Ph.D. Environmental Engineering Science, 1979, California Institute of Technology, Pasadena

Dr. Pankow's academic training combines basic chemistry (BA, SUNY, 1973) with engineering (Ph.D., Caltech, 1979). His research has involved the application of chemical principles to understanding how chemicals partition in important multi-phase systems. A primary focus of Dr. Pankow's work has involved the "gas/particle (G/P) partitioning" process, i.e., how compounds distribute themselves between the gas phase and the associated particles of aerosol systems. G/P partitioning is of enormous fundamental importance in determining the amounts of suspended organic particulate matter (OPM) that can form in polluted regional airsheds, and in the global atmosphere. Theory developed in 1994 by Pankow provides the foundation of all contemporary model predictions of OPM formation in urban airsheds, and in the global atmosphere. Pankow has continued his study of the chemical thermodynamics of OPM formation. A primary current focus is development of methodologies to manage the molecular complexities that necessarily arise when considering OPM formation in atmospheric systems. G/P partitioning also affects the behavior and fate of toxic persistent organic pollutants (POPs) in the global atmosphere. Theory developed in 1987 and 1998 by Pankow outlines the Junge-Pankow model as used to predict how PCBs, pesticides, dioxins, polycyclic aromatic hydrocarbons, and other toxins behave in the environment. This includes consideration of how such compounds tend to be transported through the atmosphere from industrial regions in temperate climates to sensitive polar ecosystems by the cold-trapping effects of "global-distillation".


2009, Elected, National Academy of Engineering

2004, Haagen-Smit Prize

2003, "Highly Cited Researcher"

1999, Creative Advances in Environmental Science and Technology, American Chemical Society

1993, John Wesley Powell Award (U.S. Geological Survey National Citizen Achievement Award)

Jeremy Parra

Adjunct Professor of Environmental Science and Physics

Ph.D. Applied Physics, 2012, Portland State University

Atmospheric Chemistry; Spectroscopy; Instrument Development

Dr. Parra's academic training is in mathematics and physics with an emphasis on instrumentation and atmospheric chemistry. Dr. Parra's work has focused on urban air chemistry, with specific interest in the study of air-surface chemistry. Dr. Parra, in addition to running his own data company worked in industry on the development of instruments for measuring atmospheric particles. His current research is on the development spectroscopic techniques for in situ measurements of urban pollutants at points of origin.

Andrew Rice

Assistant Professor of Physics

Ph.D. Chemistry, 2002, University of California, Irvine

Stable Isotopes; Atmospheric Trace Gases

Future forecasting of the Earth's climate relies heavily on the ability to predict concentrations of atmospheric trace gases. Yet a comprehensive understanding of processes which control current levels of important radiative (e.g., carbon dioxide, methane) and non-radiative (e.g., carbon monoxide, molecular hydrogen) trace species is far from complete. The Rice research group focuses on using small variations in naturally occurring stable isotopes to trace the sources and sinks of reactive trace gases. This investigative tool has emerged as important new method for investigating the complex processes that lead to changes in atmospheric composition and the consequent effects on climate and chemistry. Current research projects include using routine measurements of stable isotopes in atmospheric methane and molecular hydrogen to better constrain their budgets and understand recent short and long term trends in their atmospheric abundances. Additionally, the Rice group is interested in using stable isotopes to better understand the budgets of several important atmospheric volatile organic compounds including methyl chloride, isoprene, and formaldehyde.

In the newly established Stable Isotope Laboratory, Dr. Rice and coworkers develop state-of-the-science analytical techniques to analyze air samples to unprecedented levels of accuracy and precision. These measurements involve regularly quantifying differences in ratios of stable isotopes (e.g., 13C/12C and D/H) as small as one part in ten thousand on gases that have abundances of one part in a million and lower. Recent work has included the analysis of trace gases collected world-wide in source regions including urban atmospheres, rice paddies, and landfills. In remote atmospheres the Rice group has analyzed air collected aboard ocean-going vessels in the Pacific and Atlantic Oceans, the NASA ER-2 aircraft, and from stationary sites including Cheeka Peak, WA and Montana de Oro, CA. Ultimately, isotopic measurements can be useful for identifying important sources and sinks of trace gases, evaluating trends in their abundance, and understanding the spatial distributions of source strengths.

Todd Rosenstiel

Associate Professor of Biology

PhD, 2004, Ecology and Evolutionary Biology, University of Colorado, Boulder

Plant Physiology; Atmospheric CO2 and Plant Metabolism

Research in the Rosenstiel lab at PSU examines how key components of climate change, e.g., elevated CO2, temperature and ozone, influence the metabolism and physiology of plants, particularly forest trees. The Rosenstiel group is interested in developing a mechanistic understanding of how plant metabolism responds to climate change factors in order to establish how the form and function of forested ecosystems will be altered in the future. Current projects include identifying key genes and biochemical processes that directly link atmospheric CO2 concentration to the production and release of volatile organic compounds, such as isoprene, from tree leaves. The release of highly reactive volatile compounds, like isoprene, from forested ecosystems is one of the primary principal controls over the oxidative photochemistry of the lower atmosphere, strongly influencing the regional production of smog, as well as the lifetime of key greenhouse gases. Work in the Rosenstiel lab has discovered a surprising direct effect of atmospheric CO2 concentration on regulating the production of leaf isoprene emission. Ongoing work suggests that continued increases in atmospheric CO2 are likely to have dramatic consequences for wide-ranging aspects of plant metabolism, including reducing a tree's ability to protect itself against insect damage. The Rosenstiel group is currently working with an international team of physiologists, atmospheric chemists, and mathematical modelers in an effort to develop new methodologies for more accurately predicting the nature of biosphere-atmosphere interactions in a changing climate.