CAREER: Natural Organic Matter Mediated Processes in the Subsurface: Heavy Metal Adsorption and Nanoparticle Migration

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0954991Lenhart Natural organic matter (NOM), the product of natural biological and chemical processes, is a heterogeneous mixture of organic molecules of varying size and reactivity that is ubiquitous in nature. NOM controls the environmental fate of contaminants and particles and this career development plan will elucidate specific details of how NOM acids of environmental significance influence the fate of lead and nanoparticulate iron oxides in soil and ground water systems. The specific research objectives are to: (a) characterize the coordination structures of NOM acids at iron oxide/water interfaces and determine how the acids influence lead coordination at the same interfaces, and (b) relate the coordination modes and structures of NOM acids at iron oxide/water interfaces to the resultant transport of nano-sized iron oxide particles through porous media. The research will combine atomic-, molecular-, microscopic-, and macroscopic-level techniques with hydrodynamically-active experiments in order to provide direct information of unprecedented detail on lead speciation and nanoparticle transport as influenced by NOM. The research will elucidate specific detailed information of NOM coordination at mineral interfaces. Current reactive transport and chemical speciation models do not appropriately account for these interactions and produce erroneous predictions. The role that different components of NOM, namely acids of known structure and those of heterogeneous structure, have on determining heavy metal behavior will be determined. Research on the transport of nano-sized hematite through porous media in the presence of NOM will contribute to the emerging fields of environmental nanoscience and nanotechnology and will provide information needed to assess the risk of nanoparticles in the environment. The novel combination of macroscopic-, microscopic-, molecular-, and atomic-level techniques for NOM and lead adsorption will provide information of unsurpassed resolution. In addition to the direct benefits to contaminated site management and particle transport, the detailed information collected from this work will also benefit research on in situ contaminant remediation and water treatment. Solving the critical environmental problems our society faces will require a concerted effort by scientists, engineers, and policy makers with widely varying backgrounds. Preparing these individuals for such a task requires an educational system that places emphasis on providing all students with a sound foundation in the natural and physical sciences as they apply to the environment. The goal of this educational plan is to establish a framework to impart sound environmental science and engineering concepts to multiple components of the STEM pipeline, from middle school through graduate school and to students across a spectrum of ethnic, social, and gender groups. To meet this educational goal the PI will perform outreach to K-12 teachers and students through professional development and electronic videoconferencing initiatives, integrate undergraduate and graduate students into multi-disciplinary teams, and enhance learning outcomes in graduate and undergraduate courses by incorporating real-world examples, team-based assignments, and professional practice topics. The integrated research and education efforts will reach a wide audience, and through outreach and recruitment activities, will increase the participation of diverse groups in science and engineering. Outreach initiatives will reach out to K-12 students and teachers in the local community and across the country. Dissemination of the scientific results will be wide and will contribute to the fields of environmental engineering, environmental chemistry, surface chemistry, and aqueous geochemistry. New course components will incorporate critical skills such as team-work, leadership and problem-solving thereby better preparing students for professional success upon graduation. The improved mechanistic and structural information of heavy metal speciation in heterogeneous systems will benefit society by improving site remediation and management practices. The details on the transport of the nano-sized hematite will also provide specific information needed to develop a regulatory system to manage the discharge of anthropogenic nanomaterials. Finally, it is expected that closely coordinating the research, educational and outreach activities will foster a greater awareness among all participants of the importance and application of research and engineering in society.