Sharon Walker
Bourns B355 |
Sharon WalkerAssistant Professorthe John Babbage Chair in Environmental Engineering Chemical & Environmental Engineering
Sharon Walker received her Ph.D. in Environmental Engineering, from the Department of Chemical Engineering at Yale University in 2004. She earned her M.S. in Chemical and Environmental Engineering from Yale in 2000 and two Bachelor of Science degrees from the University of Southern California in Environmental Engineering and Environmental Studies in 1998. She is a member of the American Chemical Society (ACS), American Society of Microbiology (ASM), Association for Environmental Engineering and Science Professors (AEESP), American Society of Civil Engineers (ASCE), and Society of Women Engineers (SWE). She is also a member of Chi Epsilon and Tau Beta Pi. She is currently a faculty advisor to the UC Riverside Alpha Beta chapter of Tau Beta Pi and the Society of Women Engineers UCR chapter. She was awarded the 2008 Woman of Distinction Award by the Girl Scouts of San Gorgonio Council for her outreach efforts in Science Technology, Engineering, and Math (STEM) education.
RESEARCH TOPICS
Dr. Walker's research interest lies at the intersection of physical, chemical, and biological processes in natural and engineered aquatic systems. In particular, work has focused on understanding the factors controlling particle adhesion and transport in subsurface environments. The emphasis has been to explore the fundamental mechanisms involved in cellular adhesion, and the interactions occurring at the molecular scale between the bacterium and mineral surfaces. These mechanisms apply to not only to bacterial-mineral interactions, but also between bacteria with surfaces such as membranes, filter media, and biomedical materials. Additionally, these approaches are applied to the area of nanoparticle stability and fate in aquatic environments. The overall goal of Dr. Walker's work is to optimize effective water treatment and distribution, wastewater reclamation, and to understand mechanisms controlling particle transport in aquatic environments. Current research areas include the following: 1.Application molecular techniques to find possible links between genetic characteristics of bacteria and their adhesion and transport behavior, and expanding current predictive capability for transport of various bacterial species in aquatic systems. 2.Examination of the sensitivity of bacterial adhesion to physical and chemical fluctuations as would occur in natural (i.e. groundwater) and engineered (i.e. water and wastewater treatment plants) systems through the investigation of the removal of cells in a radial stagnation point flow (RSPF) system, a parallel plate (PP) flow chamber, and traditional packed bed columns. 3.Study of nanoparticle attachment and detachment kinetics in flowing systems.
AWARDS
• UC Riverside, John Babbage Chair (1/1/05 - 6/30/2008)
SELECTED PUBLICATIONS
Lin, H.K., Pryadko, L.P., Walker, S.L., and Zandi, R., 2009, “Attachment/detachment rate distributions in deep bed filtration” Physical Review E 79, 046321
Kim, H.N., and Walker S.L ., 2009, “ Escherichia coli transport in porous media: Influence of cell strain, solution chemistry, and temperature” Colloids and Surfaces B: Biointerfaces ( doi:10.1016/j.colsurfb.2009.02.002 )
Hong,Y., Rheem, Y, Lai, M. Cwiertny, D.M., Walker , S.L. and Myung, N.V., 2009, “ Electrochemical synthesis of FexNi1-x nanostructures for environmental remediation” Chemical Engineering Journal 151 (2009) 66–72 Haznedaroglu, B.Z, Kim, H.N., Bradford, S.A., and Walker S.L., 2009, “Relative Transport Behavior of Escherichia coli O157:H7 and Salmonella enterica serovar pullorum in Packed Bed Column Systems: Influence of Solution Chemistry and Cell Concentration” Environmental Science and Technology 43, 6: 1838-1844 Bolster C.H., Cook, K.L., Haznedaroglu, B.Z., and Walker, S.L., 2009, “ The Transport of Mycobacterium avium subsp. paratuberculosis through Saturated Aquifer Materials” Letters in Applied Microbiology
48:307–312
Chen, G., Bedi, R., Beving, D, Yan, Y., and Walker, S.L., 2009, “The antimicrobial effect of zeolite surfaces on bacterial deposition in a parallel plate flow chamber” Langmuir 25 (3), 1620-1626 Kline, T.R., Chen, G., and Walker, S.L., 2008, “Colloidal deposition on remotely controlled charged micropatterned surfaces in a parallel plate flow chamber” Langmuir 24 (17), 9381-9385 Bolster, C.H., Haznedaroglu, B., and Walker, S. L., 2009, “Diversity in cell properties and transport behavior among 12 environmental Escherichia coli isolates” Journal of Environmental Quality 38:465–472 Tazehkand, S.S., Torkzaban, S., Walker, S.L., and Bradford. S.A. 2008, “Cell preparation methods influence E. coli D21g surface chemistry and transport in saturated porous media” Journal of Environmental Quality 37:2108-2115. Torkzaban, S., S. S. Tazehkand, S. L. Walker, and S. A. Bradford 2008, Transport and fate of bacteria in porous media: Coupled effects of chemical conditions and pore space geometry, Water Resour. Res., 44, W04403, doi:10.1029/2007WR006541. Torkzaban, S., Bradford. S.A., and Walker, S.L., 2008, “Colloid transport in unsaturated porous media: The role of water content and ionic strength on particle straining” Journal of Contaminant Hydrology 96:113-127 Haznedaroglu, B., Bolster, C.H., and Walker, S. L. , 2008, “The role of starvation on bacterial adhesion and transport in saturated porous media” Water Research 42:1547-1554
Torkzaban, S., Bradford. S.A., and Walker, S.L., 2007, “Resolving the coupled effects of hydrodynamics and DLVO forces on colloid attachment to collector surfaces” Langmuir, 23 (19), 9652 -9660. 10.1021/la700995e S0743-7463(70)00995-2
Chen, G. and Walker, S.L., 2007 “The role of solution chemistry and ion valence on the adhesion kinetics of groundwater and marine bacteria” Langmuir 23 (13) 7162-7169, doi:10.1021/la0632833
Bradford. S.A., Torkzaban, S., and Walker, S.L., 2007 “Coupling of physical and chemical mechanisms of colloid deposition in saturated porous media” Water Research 41: 3012-3024, doi:10.1016/j.watres.2007.03.030 Bradford. S.A., Simunek, J., and Walker, S.L., 2006 “Transport of E. coli O157:H7 in Saturated Porous Media” Water Resources Research, Special Section: Colloid Transport in Subsurface Environments 42 (12), W12S12, doi:10.1029/2005WR004805 Bolster, C.H., Walker, S.L., and Cook, K.L. 2006 “Comparison of Escherichia coli and Campylobacter jejuni Transport in Porous Media” Journal of Environmental Quality 35: 1018-1025
Walker, S.L. 2005 .The Role of Nutrient Presence on the Adhesion Kinetics of Burkholderia cepacia G4g and ENV435g. Colloids and Surfaces B: Biointerfaces 45: 181-188. Walker, S.L 2005 ''The Influence of Bacterial Surface Polymers on Bacterial Adhesion and Transport in Groundwater Environments'' Journal of Harbin Institute of Technology (new series), 12: 19-26. Walker, S.L., Redman, J.A., and Elimelech, M. 2005 .Influence of Growth Phase on Bacterial Adhesion and Transport: Interaction Mechanisms Involved in Packed-Bed Column and Radial Stagnation Point Flow Systems. Environmental Science and Technology, special issue .Particles and Interfaces in Aquatic Systems, A tribute to Prof. Charles R. O.Melia. 39: 6405-6411. Walker, S.L., Hill, J., Redman, J.A. and Elimelech, M., 2005 "The Influence of Growth Phase on Adhesion Kinetics of Escherichia coli D21g. Applied and Environmental Microbiology, 71:3093-3099. |
