Charles Walker, Ph.D.

Education

Ph.D. Soil Science, The Pennsylvania State University, University Park, PA.    

Dissertation Title: Enhanced techniques for determining changes to soils receiving wastewater irrigation for over forty years.     Mentor: Dr. Henry Lin                                  

M.S. Environmental Pollution Control, The Pennsylvania State University, University Park, PA.                      

Thesis Title: The effect of organic compost amendments on nitrate and phosphate removal in wetland soil mesocosms.  Mentor: Dr. Robert Shannon

B.S. in Environmental Resource Management, The Pennsylvania State University, University Park, PA. (graduated with distinction)

Minor:  Environmental Engineering.  

Professional Experience

2016 – pres.    Supervisory Hydrologist.  United States Geological Survey. Supervise hydrologists and hydrologic technicians focusing on water-quality data collection and research.

2016 – 2016    Deputy Center Director (Acting). United States Geological Survey.  Worked with senior managers to provide organizational leadership.

2012 – pres.    Water-Quality Specialist. United States Geological Survey. Serve as a technical and quality assurance reviewer for proposals, datasets and reports.

2010 – 2016    Hydrologist.  United States Geological Survey. Project leader for water resource investigations.

2006 – 2010    Post-doctoral Research Associate. The Pennsylvania State University, University Park, PA.  Developed methods to measure and model estrogen transport 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.

Teaching Experience

2012 – 2013    Instructor. Geography of Soils. University of Maryland, Baltimore County. Baltimore, MD.

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

2000 – 2006    Teaching Assistant.  The Pennsylvania State University, University Park, PA.

Instructed undergraduate student laboratories for the following courses:

• Environmental Problem Solving (ERM 412)***

• The Effects of Pollution on Water (ERM 432)**
• Introductory Soils (Soils 101)***
• Hydropedology (Soils 405)***

(* denotes sections taught)

Referred Journal Articles

Lorah, M.M., C.W. Walker, and D. Graves. 2015. Performance of an anaerobic, static bed, fixed film bioreactor for chlorinated solvent treatment.  Biodegradation. 26: 341-357.

Walker, C.W., J. Watson, and C. Williams. 2012.  Occurrence of carbamazepine in soils under different land uses receiving wastewater. Journal of Environmental Quality. 41: 1263-1267.

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.W., 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 ASABE 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

Walker, C.W., Lester, T.R., and Nealen, C.W., 2019, Hydrologic study at Farm Creek Marsh, Dorchester County, Maryland, from April 2015 to April 2016: U.S. Geological Survey Scientific Investigations Report 2019–5032, 12 p., https://doi.org/10.3133/sir20195032.

Walker, C.W., Degnan, J.R., Brayton, M.J., Cruz, R.M., and Lorah, M.M., 2015, Surface geophysics and porewater evaluation at the Lower Darby Creek Area Superfund Site, Philadelphia, Pennsylvania, 2013: U.S. Geological Survey Data Series 927, 6 p., http://dx.doi.org/10.3133/ds927

Lorah, M.M., Walker, C.W., Baker, A.C., Teunis, J.A., Majcher, E.H., Brayton, M.J., Raffensperger, J.P., and Cozzarelli, I.M., 2014, Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009–12: U.S. Geological Survey Scientific Investigations Report 2014–5140, 89 p.

Dieter, C.A., Koterba, M.T., Zapecza, O.S., Walker, C.W., and Rice, D.E., 2013, 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 2012–5263, 219 p. First posted January 17, 2013.

Conference Abstracts

Walker, C.W., M. Lorah, 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., 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., C.W. Walker, A. Baker, and D. Graves, J. Wrobel. 2010. Removing chlorinated solvents from contaminated groundwater using an above-ground bioreactor system.  19^th 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.

Invited Lectures

2011 “Pharmaceuticals and Personal Care Products in the Environment” The Philipsburg Kiwanis Organization, Philipsburg, PA.

2008 “Experiences as an Environmental Scientist” The Pennsylvania State University, Environmental Seminar. 

2007 “Soil Testing for Land Development” PA Housing and Land Development Conference, Harrisburg, PA.

2006 “Changes to soil properties after decades of wastewater irrigation” Geological Society of America Field Trip. University Park, PA.

2004 “Instrumentation for determining the soil’s hydraulic conductivity” PA Department of Environmental Protection, Storm Water Training Program, Rock Springs, PA.

Honors and Awards

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

2005 3^rd Place for Poster Presentation, The Pennsylvania State University’s Graduate Exhibition.

2005 Honorary Mention for Poster Presentation, Gamma Sigma Delta/ College of Agricultural Sciences Annual Research Expo.

2002 2^nd Place for Poster Presentation, The Pennsylvania State University’s Graduate Exhibition.

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

Grants and Contracts

2009 – 2010 Fate and Transport of Selected Pharmaceuticals in Soils.  Project Leader. $42,942. Supported by The Pennsylvania State University Office of the Physical Plant.

2008 – 2009 Occurrence of Selected Pharmaceuticals in the Soils at the Wastewater Irrigation Facility.  Project Leader. $33,867.  Supported by The Pennsylvania State University Office of the Physical Plant. 

2008 – 2009 Occurrence, Fate, and Transport of Arsenic in Soils. $24,000.  Supported by USDA-ARS. 

2007 – 2008 Fate and Transport of Selected Pharmaceuticals in Soils.  Project Leader. $38,776. Supported by The Pennsylvania State University Office of the Physical Plant. 

2007 – 2008 Real-time continuous monitoring of soil functions. $53,337. Supported by The Pennsylvania State University Office of the Physical Plant.  

Consulting Experience

Co-founder of Agricultural Research Instrumentation and Consultation.  State College, PA.  Design and fabrication of custom research equipment.

Service (Peer Review)

Journal of Environmental Quality        

Agricultural Water Management

Soil Science Society of America Journal

Transactions of ASABE

Environmental Technology