Rationale: Evaluation of the hazardous impact of environmental contaminants on the earth's ecological system depends critically on our ability to project and model the reactive and non-reactive flow of these species on a geological length scale. Because of its importance, there has been extensive research in measuring and modeling these transport processes, taking into account a variety of hydrological and soil phenomena. The majority of this work has taken a macroscopic viewpoint; however, a detailed understanding of these processes at the molecular-level is now both possible and extremely important. A knowledge of molecular-level transport and chemistry can provide critical information needed to enhance the generality and predictive power of large-scale models, to identify the possible chemical and biological factors influencing contaminant decay rates, or to assess how changes in macroscopic parameters such as temperature might influence modeling parameters.

The Environmental Molecular Sciences Institute (EMSI), funded jointly by the NSF and the DOE, unites Columbia's traditional strengths in chemical and geological sciences, bringing together 7 faculty senior investigators (George Flynn, Richard Friesner, Tony Heinz, Richard Osgood, Stephanie Pfirman, Peter Schlosser, and Nicholas Turro) and a number of other faculty participants with special expertise in a broad variety of scientific disciplines. The Institute activities are divided into three Research Areas corresponding to the different length scales of importance in this program: atomic (a few angstroms); microscopic (0.01 - 10 m m); and macroscopic, (½ 1 km); and one Education/Outreach Area. Research on the angstrom length scale is further subdivided into efforts in UHV surface science (section I), theory (section II), and interface science (section III). The EMSI will be a central component of a recent major University-wide initiative in environmental research and policy. With this initiative the Columbia Earth Institute (CEI) has been established, and the University has made a major and unprecedented commitment to integrate research and educational activities across its 15 schools with the goal of providing the basis for wise stewardship of our planet. The program is strongly collaborative with and builds on facilities and staff at DOE's Environmental Molecular Sciences Laboratory (EMSL) at the Pacific Northwest National Laboratory (PNNL). Columbia's major research center in the geological sciences, the Lamont-Doherty Earth Observatory (L-DEO), will also be a major contributor to this effort through its extensive staff and facilities. The program will encompass a basic experimental and theoretical molecular core, modeling and measurements of species transport, and microscopic studies of reactive migration in porous media. It is, of necessity, highly interdisciplinary, including faculty from five academic departments and extensive collaborations with the Chemical Structure and Dynamics; the Theory, Modeling, Simulation; and the Environmental Dynamics and Simulation Groups at PNNL.

Although the proposed work involves significant and extensive collaborations with scientists at PNNL and is, therefore, focused on environmental issues of special interest to the Hanford, WA DOE site, the scientific questions to be addressed have wide applicability to the chemical, automotive, and electronics industries, as well as to the operation of the huge Fresh Kills landfill and the North River Sewage Treatment Plant, both of which are within the confines of New York City. The key issues shared by all of these sites and industries are the chemical fate and transport properties of organic material and heavy metals as they move through soil with significant metal oxide content, and the modification of these processes through the action of water solvent and the catalytic activity of biological (enzymatic) material. For example, in the automotive industry a major source of pollution is the foundry sands used for metal castings of automotive parts, which contain organic binders and heavy metal contaminants that eventually become lechate from waste sand piles. (Foundry sand accounts for the largest volume of solid waste generated by the auto industry (1.5M tons)). Similarly, at the Fresh Kills landfill (the largest in the world), a controlled version of many of the problems that beset the auto industry and DOEâs Hanford site exist. As a result of this remarkable commonality of intellectual interest, Columbia's effort under this program includes collaborative interactions with a number of nearby industrial companies (DuPont, Exxon, General Electric, and Inrad), while both the Fresh Kills landfill and the North River Sewage Treatment Plant provide opportunities for undergraduate and graduate field trips as well as nearly unlimited access to real world soil and water samples.

Intellectual Focus: The Institute primarily addresses fundamental chemical questions associated with subsurface contaminants, particularly those associated with porous or particulate substrates, and focusses on the role of microscopic chemical sinks (species loss) and sources (species transformation or creation) in contaminant migration and reaction. Axiomatic to this effort is the belief that chemical reaction and transport processes must be understood at the most fundamental molecular, angstrom length scale while at the same time being rationally informed by the macroscopic behavior of landfills and pollution sites where phenomena take place on the kilometer scale. Thus our approach "begins" with studies of the structure of controlled, model oxide surfaces, the physical and chemical behavior of organic and heavy metal adsorbates on these surfaces, and the effects of co-adsorbate water molecules on both the structure and reactivity of these surfaces and adsorbates. In parallel with this effort, a series of studies will be conducted that are designed to use highly sophisticated, state-of-the-art, linear and non-linear optical spectroscopies and scanning probe microscopies to follow with great specificity the structural changes and reactions taking place at liquid-solid interfaces under ambient conditions. In addition a second parallel ambient condition study will encompass investigations of the transport and reactions of organic and heavy metal pollutants taking place within the cavities of porous and particulate oxides and zeolites. At each stage of this process collaborative theoretical studies will be conducted at both Columbia and PNNL, to provide both the rationale and predictive capability for our studies. Macroscopic geochemical probes will be employed to test the predictions of the models derived from this molecular level understanding.

Goals: The goal of the research is to address and integrate questions of molecular chemistry on three characteristic length scales: atomic (a few angstroms); microscopic (0.01 - 10 m m); and macroscopic, (½ 1 km). These efforts attack related research questions but from very different perspectives. For example, some small organic molecules are known to be excellent "tracers" for environmental contaminant migration. We expect to determine the length scales over which these tracers persist; the mechanism for migration of organic contaminant molecules on a microscopic level in highly particulate or porous soils; the binding and reactivity of these species on hydrated, metal-oxide surfaces; the static and dynamic behavior of pollutants on model surfaces, meant to mimic the behavior of real world ecological systems; the mechanism and dynamics of chemical decomposition on these surfaces and their modification by interaction with biological organisms; and, finally, the efficiency and accuracy of high level theoretical calculations in predicting the behavior of these complex chemical systems.

Expected Outcomes: The overriding themes that connect the different stages of this effort are surface assisted redox chemistry, especially as modified by the presence of solvent and pH changes, and the nature of molecular transport, which on the microscopic (mm) scale is exceedingly complex due to the possibility of reactions and the constricted flow of material through small pore, oxide laden soils. Although the logic proceeds from the most well defined UHV molecular scale study of surfaces to the macroscopic behavior of a huge aquifer system, we expect discoveries and information obtained at each level to instruct activities at other levels.

It is our expectation that the outcome of these studies will be a highly detailed, fundamental and accurate picture of the "birth to death" scenario for heavy metal and organic pollutants in porous soils. Our intent is to provide sufficient information to the professional environmental modeling community to aid in developing a more general view of some portions of the modeling process. Studies of this kind will also yield insight into those rate limiting chemical reactions and physical phenomena that are key to any model that can successfully predict the behavior of large scale aquifers. Linking of the fundamental studies proposed here to real-world problems is extremely challenging, since effective approaches for combining molecular level information with microscopic and macroscopic systems are not yet well developed. Training scientists to work across these length scales is, thus, critical in developing experimental and theoretical techniques that will over time lead to the evolution of scaling and linking strategies.

We also plan to develop a simplified transport model and to use this large scale, simplified model in both classroom demonstrations of pollutant flow and in outreach activities to educate the public about environmental issues. The outreach activities will be conducted both locally in New York City (at Columbia, at the Fresh Kills landfill, at the North River Treatment Plant, at New York City's Museum of Natural History) and at Columbia's Biosphere 2 complex in Arizona, which hosts more than 200,000 visitors per year. As a result of the activities of the Institute, there will be a substantial enhancement of undergraduate and graduate research and course work in the environmental sciences at Columbia.

This material is based upon work supported by the National Science Foundation under Grant No. 9810367. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.