Charles Walker, Hydrologist/Water-Quality Specialist

Education

Ph.D.

Ph.D. in Soil Science. Specialized in Soil Physics and Landscape Hydrology. Pennsylvania State University, 2006.

M.S.

M.S. in Environmental Pollution Control. Specialization in Treatment Wetland Systems. Pennsylvania State University, 2002.

B.S.

B.S. in Environmental Resource Management (Minor in Environmental Engineering). Pennsylvania State University, 2000.

Professional Experience

2012 – present, Water Quality Specialist (Acting). United States Geological Survey. Serve as a technical and quality assurance reviewer for proposals, datasets and reports.

2012 – present, Instructor. Geography of Soils. University of Maryland, Baltimore County. Baltimore, MD.

2010 – present, Hydrologist. United States Geological Survey. Project leader for contaminant fate and bioremediation research and applications.

2008 – 2011, Instructor. Introductory Soils (Soils 101 – Online). The Pennsylvania State University, University Park, PA.

2006 - 2010, Post-doctoral Research Associate, The Pennsylvania State University, University Park, PA. Developed methods to measure and model the occurrence, fate and transport of endocrine disrupting hormones and pharmaceutical compounds through soils.

2002 - 2006, Graduate Research Assistant/Laboratory Supervisor, The Pennsylvania State University, University Park, PA. Supervised a soil laboratory used by graduate and undergraduate students for their research projects.

2000 - 2002, Graduate Research Assistant/Laboratory Supervisor, The Pennsylvania State University, University Park, PA. Supervised a water quality laboratory used by graduate and undergraduate students for their research projects.

1998 - 2000, Research Assistant, Department of Agricultural and Biological Engineering Fabrication Shop, The Pennsylvania State University, University Park, PA. Assisted graduate students with fabrication of their research projects.

Associations and Memberships:

Professional Organizations

• Soil Science Society of America
• American Geophysical Union

Service

• Reviewer, Journal of Environmental Quality
• Reviewer, Agricultural Water Management
• Reviewer, Soil Science Society of America

Research / Professional Focus / Current Projects

The main goal of my research is to study the occurrence, transport and remediation of pollutants. I strive to apply, improve and develop the latest technology to solve environmental issues. Previous projects involving treatment wetlands, landscape hydrology, soil physics, wastewater irrigation and emerging contaminants have allowed me to gain an appreciation for solving complex problems by understanding interactions between aquatic and terrestrial systems. Currently, I am part of a team of hydrologists that focuses on the fate and bioremediation of chlorinated compounds. Many of our projects utilize existing wetlands that naturally occur at the contaminated sites. Wetland systems can often facilitate microbial communities that degrade a variety of organic compounds. If degradation is not complete, we can enhance the removal processes through bioaugmentation and biostimulation of bacteria. If wetlands are not present at the site, we can sustain the pollution-degrading microbial consortia and environments in flow-through bioreactors. These enhancements are not only effective in removing the pollution; they are also a sustainable treatment technology.

Another goal of my research is to develop state of the art methodology and research equipment. I am currently developing radio controlled equipment that can measure a variety of water quality parameters within a body of water.

I have experience and training with the Campbell Scientific Datalogger System, wiring and programming; electronics, simple circuit board design and fabrication; metal work, machining, fabrication and welding; and heavy equipment operation.

Selected Bibliography

Referred Journal Articles

Walker, C.W., J. Watson, and C. Williams. 2012. Occurrence of carbamazepine in soils under different land uses receiving wastewater. Journal of Environmental Quality. In press-Accepted.

Castellano MJ, Schmidt JP, Kaye JP, Walker C.W., Graham C, Lin H, Dell C. 2011. Soil water controls on heterotrophic respiration. Geoderma doi: 10.1016/j.geoderma.2011.01.020

Walker, C.W., and J. Watson. 2010. Adsorption of estrogens to laboratory materials and filters during sample preparation. Journal of Environmental Quality. 39: 744-748

Jacobsen, K. L., R.S. Gallagher, M. Burnham, B. B. Bradley, Z. M. Larson, C.W. Walker and J.E. Watson. 2010. Mitigation of Seed Germination Impediments in Hairy Vetch. Agronomy Journal 102: 1346-1350.

Castellano MJ, Schmidt JP, Kaye JP, Walker C, Graham C, Lin H, Dell C. 2010. Biogeochemical and hydrological controls on nitrous oxide emissions across an agricultural landscape. Global Change Biology. doi: 10.1111/j.1365-2486.2009.02116.x.

Walker, C.W., J. Watson, and R. Thomas. 2009. Design of a low-cost, flow-through electrical conductivity probe. Applied Engineering in Agriculture 25: 373-376.

Walker, C.W., and H. Lin. 2008. Soil property changes after four decades of wastewater irrigation: A landscape perspective. Catena 73: 63-74.

Walker, C.W., and R.D. Shannon. 2006. Nitrate and phosphate removal effects of compost amendments in wetland mesocosms. Transactions of the American Society of Agricultural and Biological Engineers 49:1773-1778.

Walker, C.W., H. Lin, and D.D. Fritton. 2006. Is the tension beneath a tension infiltrometer what we think it is? Vadose Zone Journal 5:860-866.

Lin, H., W.J. Kogelmann, C.W. Walker, and M.A. Bruns. 2006. Soil moisture patterns in a forested catchment: A hydropedological perspective. Geoderma 131:345-368.

Peer-Reviewed Reports

Koterba, M.T., C.A. Dieter, O, S. Zapecza, C. W. Walker, and D. E. Rice. (In Review) Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area and Vicinity, Cecil County, Maryland, 2010-11. U.S. Geological Survey Scientific Investigations Report. In review.

Conference Abstracts

Walker, C.W., Lorah, M.M, A. Baker, and D. Graves. 2012. Pilot-scale anaerobic bioreactor system for removal of 1,1,2,2-tetrachloroethane and trichloroethane from contaminated groundwater at Aberdeen Proving Ground, Maryland, 2011. Eighth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, CA.

Lorah, M.M., C.W. Walker, J. Teunis, D. Graves and W. Schneider. 2011. Transformation products and rates for chlorinated ethanes and ethenes by an anaerobic dechlorinating consortium. Battelle Bioremediation Conference. Reno, NV.

Lorah, M.M, C.W. Walker, A. Baker, and D. Graves, J. Wrobel. 2010. Removing chlorinated solvents from contaminated groundwater using an above-ground bioreactor system. 19th Annual Maryland Ground Water Symposium. Baltimore, MD.

Walker, C.W., J. Watson, Z. Larson, and J. Gaudlip. 2009. The Pennsylvania State University’s Wastewater Irrigation System: 30 billion gallons and still spraying. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.

Larson, Z., C.W. Walker, and J. Watson. 2009. The effects of long term wastewater irrigation on soil physical properties. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.

Watson, J., C.W. Walker and Z. Larson. 2009. Concentration dependent sorption of estrone to soil. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.

Petersen, G., B. Ketchum, C.W. Walker and A. Khouzani. 2009. A digital introductory soils course for the virtual classroom. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.

Walker, C.W., J. Watson, J. Dec, and Z. Larson. 2008. Wastewater irrigation: The potential to increase biofuel production while removing endocrine disrupting hormones. 2008 Mid-Atlantic Regional Water Resources Research Conference: The Water-Energy Nexus: A Necessary Synergy for the 21st Century. Shepherdstown, West Virginia.

Walker, C.W., J. Watson, and R. Thomas. 2007. Design of a low-cost, flow-through electrical conductivity probe. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.

Walker, C.W., H. Lin, X. Zhou, Z. Zhang, and P. Reed. 2007. Simple electronic device for measuring shallow ground water level. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.

Watson, J., and C.W. Walker. 2007. Soil Water Variability and Crop Yields. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.

Castellano, M., C.W. Walker, J. Schmidt, C. Dell, J. Kaye, and H. Lin. 2007. Soil nutrient transport and transformation during extreme water table fluctuations in an agro-ecosystem. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.

Luo, L., H. Lin, and C.W. Walker. 2007. Quantitative relationship between soil structure and preferential flow and transport in contrasting soils and land uses. Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract H23G-1717.

Walker, C.W., and H. Lin. 2006. Hydropedology in action: Soil changes after 40 years of wastewater irrigation. 18th World Congress of Soil Science, Philadelphia, Pennsylvania.

Zhou, X., H. Lin, C.W. Walker, and Q. Zhu. 2006. A hydropedologic study of subsurface water flow in a forested catchment. 18th World Congress of Soil Science, Philadelphia, Pennsylvania.

Lin, H., Q. Zhu, C.W. Walker, and X. Zhou. 2006. Precision soil mapping for identifying hydropedologic functional units over an agricultural landscape. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Indianapolis, Indiana.

Walker, C.W., and H. Lin. 2004. Is the tension delivered by a tension infiltrometer what we think it is? International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Seattle, Washington.

Other Information

   Honors and Awards

2006 Outstanding Graduate Student Presentation (Oral), Northeastern Branch of the ASA/SSSA Meeting in Philadelphia, PA.

2002 Induction into Gamma Sigma Delta Honor Society, Penn State Chapter.