Daniel H Doctor

Dan began a career with the USGS in 2002 as an NRC postdoc within the Isotope Tracers of Biogeochemical and Hydrologic Processes project of the National Research Program in Menlo Park, California. In 2006, he joined the Karst Applied Research Studies (KARST) project of the Eastern Geology and Paleoclimate Science Center in Reston, Virginia. Currently he serves as a field geologist conducting 1:24,000 scale geologic mapping focused on karst regions in the northern Great Valley of Virginia and West Virginia. His current research interests include karst hydrology and geomorphology, mapping sinkhole susceptibility utilizing LIDAR data, and paleoclimate records from karst regions.

Education:           

Ph.D. (2002) in Hydrogeology/Geochemistry, with Doctoral Minor in Water Resources Science, University of Minnesota, Dept. of Geology and Geophysics, Minneapolis, MN

Dissertation title: The Hydrogeology of the Classical Karst (Kras) Aquifer of Southwestern Slovenia

Bachelor of Arts (1994) in Geology, Minor in Environmental Studies

Colgate University, Hamilton, NY (Magna Cum Laude, Phi Beta Kappa)

Professional Experience:           

Research Geologist (2006-present). U.S. Geological Survey, KARST Project, Eastern Geology and Paleoclimate Science Center, Reston, VA

Hydrologist (2004-2006). U.S. Geological Survey, Isotope Tracers Group, Water Resources Division, Menlo Park, CA

Postdoctoral Research Associate, National Research Council (NRC) (2002-2004). U.S. Geological Survey, Isotope Tracers Group, Water Resources Division, Menlo Park, CA

Project Analyst (2001). Lands and Minerals Division, Minnesota Department of Natural Resources (MN-DNR).

SELECTED PUBLICATIONS

Doctor, D.H. and Parker, R.A. (2018) Geologic map of the Hayfield Quadrangle, Frederick County, Virginia. U.S. Geological Survey Scientific Investigations Map 3407, 1 sheet, 1:24,000 scale. 

Benton, J. R., Doctor, D.H. (2018) Investigating Vadose Zone Hydrology in a Karst Terrain through Hydrograph and Chemical Time Series of Cave Drips at Grand Caverns, Virginia. In: Sasowsky, I.D., Land. L., and Byle, T., eds., National Cave and Karst Research Institute Symposium 7, Proceedings of the 15th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst, April 2-6, Shepherdstown, WV, pp. 213-219. [Link]

Orndorff, W., Doctor, D.H., Malabad, T.E., Kosic-Ficco, K., Orndorff, Z., Futrell, A. (2018) Patterns of heterogeneity within phreatic karst aquifers of the Great Valley, Virginia and West Virginia: evidence from time series hydrologic monitoring, groundwater chemistry, and stygobite site occupancy. In: Sasowsky, I.D., Land. L., and Byle, T., eds., National Cave and Karst Research Institute Symposium 7, Proceedings of the 15th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst, April 2-6, Shepherdstown, WV, pp. 189-201. [Link]

Waters, B.B., Doctor, D.H., Maynard, J. P. (2018) Using geophysics to map bedrock faults, dikes, and surficial geology in relation to karst features in the Briery Branch quadrangle, Rockingham County, Virginia. In:Sasowsky, I.D., Land. L., and Byle, T., eds., National Cave and Karst Research Institute Symposium 7, Proceedings of the 15th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst, April 2-6, Shepherdstown, WV, pp. 235-240. [Link]

Haynes, J. T., Pitts, A. D., Doctor, D. H., Diecchio, R. J., Blake, B. M., Jr., (2018) Appalachian Basin Stratigraphy, Tectonics, and Eustasy from the Blue Ridge to the Allegheny Front, Virginia and West Virginia: West Virginia Geological and Economic Survey, Field Trip Guide FTG-10, 86 p. [Link] 

Doctor, D.H. and Orndorff, W. (2017) Hypogene Caves of the Central Appalachian Shenandoah Valley in Virginia, in: Klimchouk, A., Palmer, A., De Waele, J., Auler, A., and Audra, P., eds., Hypogene Karst Regions and Caves of the World: New York, Springer, ISBN: 978-319-53347-6, doi: 10.1007/978-3-319-53348-3. [Link]  

Doctor, D.H., Paybins, K., and Kozar, M.D. (2017) A GIS-based compilation of spring locations and geochemical parameters in the Appalachian Landscape Conservation Cooperative (LCC) region, In: Kuniansky, E.L., and Spangler, L.E., eds., U.S. Geological Survey Karst Interest Group Proceedings, San Antonio, Texas, May 16–18, 2017: USGS Scientific Investigations Report 2017-5023, p. 38-48, [Link]

Carmichael, S.K., Doctor, D.H., Wilson, C.G., Feierstein, J. and McAleer, R.J. (2017) New insight into the origin of manganese oxide ore deposits in the Appalachian Valley and Ridge of northeastern Tennessee and northern Virginia, USA: Geological Society of America Bulletin, pp.B31682-1. [Link]

Doctor, D.H. (2016) Karst without boundaries book review, Groundwater, Vol.54, Issue 6, pp.6-7, DOI: 10.1111/gwat.12487 [Link]

Taylor, C. J. and Doctor, D.H. (2016) Karst, Chapter 89 of Singh, Vijay P., ed., Handbook of Applied Hydrology (2nd ed.): New York, McGraw-Hill, p. 89-1 to 89-14, ISBN: 9780071835091

Doctor, D.H. and Orndorff, W. (2016) Deep phreatic influence on caves and karst in the central Appalachian Great Valley, In: T. Chavez and P. Reehling, eds., NCKRI Symposium 6, Proceedings of DeepKarst 2016: Origins, Resources, and Management of Hypogene Karst, Carlsbad, New Mexico: National Cave and Karst Research Institute, p. 89-104. [Link]

Christman, M. C., D. H. Doctor, M. L. Niemiller, D. J. Weary, J. A. Young, K. S. Zigler, and D. C. Culver (2016) Predicting the Occurrence of Cave-Inhabiting Fauna Based on Features of the Earth Surface Environment.: PloS one, v. 11, no. 8, p. e0160408, doi:10.1371/journal.pone.0160408. [Link]

Doctor, D. H., D. J. Weary, D. K. Brezinski, R. C. Orndorff, and L. E. Spangler (2015) Karst of the Mid-Atlantic region in Maryland, West Virginia, and Virginia, in D. K. Brezinski, J. P. Halka, and R. A. O. Jr., eds., Tripping from the Fall Line: Field Excursions for the GSA Annual Meeting, Baltimore, 2015: Geological Society of America, p. 425–484, doi:10.1130/9780813700403. [Link]

Doctor, D.H., E. C. Alexander, Jr., R. Jameson, and S. Alexander (2015). Hydrologic and geochemical dynamics of vadose zone recharge in a mantled karst aquifer: results of monitoring drip waters in Mystery Cave, Minnesota. In: Doctor. D.H., Land. L., and Stephenson, J. Brad, eds., National Cave and Karst Research Institute Symposium 5, Proceedings of the 14th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst, Oct. 5-9, Rochester, Minnesota, pp. 19-30. [Link]

Wall, J., D. H. Doctor, and S. Terziotti (2015) A Semi-automated Tool for Reducing the Creation of False Closed Depressions from a Filled LIDAR-derived Digital Elevation Model. In: Doctor. D.H., Land. L., and Stephenson, J. Brad, eds., National Cave and Karst Research Institute Symposium 5, Proceedings of the 14th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst, Oct. 5-9, Rochester, Minnesota, pp. 255-262. [Link]

Weary, D. J., and Doctor, D. H. (2015). Karst mapping in the United States: Past, present, and future: Geological Society of America Special Papers, v. 516, p. SPE516–04, doi:10.1130/2015.2516(04).[Link]

Eagle, S., W. Orndorff, B. Schwartz, D. H. Doctor, J. Gerst, and M. Schreiber (2015) Analysis of hydrologic and geochemical time-series data at James Cave, Virginia: Implications for epikarst influence on recharge in Appalachian karst aquifers, in J. Feinberg, Y. Gao, and E. C. Alexander, Jr., eds., Caves and Karst Across Time: Geological Society of America Special Papers, 516, p. SPE516-15, first published on August 6, 2015, doi:10.1130/2015.2516(15). [Link]

Schreiber, M. E., Schwartz, B. F., Orndorff, W., Doctor, D.H., Eagle, S. D., and Gerst, J. D. (2015) Instrumenting Caves to Collect Hydrologic and Geochemical Data: Case Study from James Cave, Virginia. In: Younos, T. and Parece, T. E., eds., Advances in Watershed Science and Assessment, The Handbook of Environmental Chemistry, Volume 33, pp 205-231. [Link]

Kendall, C., Doctor, D. H., & Young, M. B. (2014). Environmental Isotope Applications in Hydrologic Studies. In: Treatise on Geochemistry, (Second Edition), edited by Heinrich D. Holland and Karl K. Turekian, Volume 7: Surface And Groundwater, Weathering and Soils, Chapter 9, p. 273–327. Elsevier, Oxford. doi:10.1016/B978-0-08-095975-7.00510-6 [Link]

Weary, D. J., and Doctor, D. H. (2014) Karst in the United States: A digital map compilation and database: U.S. Geological Survey Open-File Report 2014–1156, 23 p.,http://dx.doi.org/10.3133/ofr20141156. [Link]

Révész, K.M., and Doctor, D.H. (2014). Automated determination of the stable carbon isotopic composition (δ13C) of total dissolved inorganic carbon (DIC) and total nonpurgeable dissolved organic carbon (DOC) in aqueous samples: RSIL lab codes 1851 and 1852: U.S. Geological Survey Techniques and Methods, book 10, chap. C20, 38 p., http://dx.doi.org/10.3133/tm10C20. [Link]

Sebestyen, S. D., Shanley, J. B., Boyer, E. W., Kendall, C., & Doctor, D. H. (2014). Coupled hydrological and biogeochemical processes controlling variability of nitrogen species in streamflow during autumn in an upland forest. Water Resources Research, 50(2), 1569–1591. doi:10.1002/2013WR013670 [Link]

Doctor, D.H., Orndorff, W., Maynard, J., Heller, M.J., and Casile, G.C. (2014). Karst geomorphology and hydrology of the Shenandoah Valley near Harrisonburg, Virginia. In: Elevating Geoscience in the Southeastern United States: New Ideas about Old Terranes—Field Guides for the GSA Southeastern Section Meeting, Blacksburg, Virginia, 2014 (Bailey, C.M., and Coiner, L.V., eds.), Geological Society of America Field Guide 35, p. 161–213, doi:10.1130/2014.0035(06). [Link]

Doctor, D.H. and Young, J.A. (2013). An evaluation of automated GIS tools for delineating karst sinkholes and closed depressions from 1-meter LIDAR-derived digital elevation data. In: Land L, Doctor DH, Stephenson JB, editors, Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Thirteenth Multidisciplinary Conference, May 6-10, Carlsbad, New Mexico: NCKRI Symposium 2. Carlsbad (NM): National Cave and Karst Research Institute, p. 449-458. [Link]

Epstein, J.B. and Doctor, D.H. (2013). Evaporite karst in the Black Hills, South Dakota and Wyoming, and the oil play in the Williston Basin, North Dakota and Montana. In: Land L, Doctor DH, Stephenson JB, editors, Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Thirteenth Multidisciplinary Conference, May 6-10, Carlsbad, New Mexico: NCKRI Symposium 2. Carlsbad (NM): National Cave and Karst Research Institute, p. 161-176.

Yager, R. M., Plummer, L. N., Kauffman, L. J., Doctor, D. H., Nelms, D. L., & Schlosser, P. (2013). Comparison of age distributions estimated from environmental tracers by using binary-dilution and numerical models of fractured and folded karst: Shenandoah Valley of Virginia and West Virginia, USA. Hydrogeology Journal. doi:10.1007/s10040-013-0997-9 [Link]

Doctor, D. H., and Doctor, K. Z. (2012). Spatial analysis of geologic and hydrologic features relating to sinkhole occurrence in Jefferson County, West Virginia. Carbonates and Evaporites, 27(2), 143–152.[Link]

Waldrop, M.P., J.W. Harden, M.R. Turetsky, D.G. Petersen, A.D. McGuire, M.J.I. Briones, A.C. Churchill, D.H. Doctor and L.E. Pruett (2012) Bacterial and enchytraeid abundance accelerate soil carbon turnover along a lowland vegetation gradient in interior Alaska. Soil Biology and Biochemistry, vol. 50, p. 188-198.

Doctor, D.H., Farrar, N.C., and Herman, J.S. (2011). Interaction Between Shallow and Deep Groundwater Components at Fay Spring in the Northern Shenandoah Valley Karst, USGS Karst Interest Group Proceedings, Fayetteville, Arkansas, April 26-29, U.S. Geological Survey Scientific Investigations Report 2011-5031, p.25-34. [Link]

Doctor, D.H. (2011) Geochemical models for investigating karst aquifers: current applications and limitations. In: Engel, A.S., Engel, S.A., Moore, P.J., and DuChene, H., eds., Carbonate Geochemistry: Reactions and Processes in Aquifers and Reservoirs. Karst Waters Institute Special Publication 16, Karst Waters Institute, Leesburg, Virginia, p. 20-22. 

Covington, M.D., Doctor, D.H., King, J.N., and Wicks, C.M. (2011) Research in karst: a model for future directions in hydrologic science? AGU Hydrology Division Newsletter, July 1, 2011, American Geophysical Union, 5 pp.

Kraus, T.E.C., Bergamaschi, B.A., Hernes, P.J., Doctor, D., Kendall, C., Downing, B.D., and Losee, R.F. (2011) How reservoirs alter drinking water quality: Organic matter sources, sinks, and transformations. Lake and Reservoir Management, vol. 27, p. 205-219. 

Gary, M.O., Doctor, D.H., and Sharp, J.M., Jr., (2011) Aqueous Geochemical Evidence of Volcanogenic Karstification: Sistema Zacatón, Mexico. USGS Karst Interest Group Proceedings, Fayetteville, Arkansas, April 26-29, U.S. Geological Survey Scientific Investigations Report 2011-5031, p.35.

Doctor, D.H., Orndorff, R.C., Parker, R.A., Weary, D.J., and Repetski, J.E. (2010). Geologic map of the White Hall quadrangle, Frederick County, Virginia, and Berkeley County, West Virginia: U.S. Geological Survey Open-File Report 2010–1265, 1 pl., scale 1:24,000, available only at http://pubs.usgs.gov/of/2010/1265. [Link]

Schwartz, B. F. and Doctor, D.H. (2009) Geomorphic and hydrogeologic evolution of karst in the Burnsville Cove, Virginia, USA: New evidence and perspectives. In: Proceedings of the Fifteenth International Congress of Speleology, July 19-26, 2009,Kerrville, Texas (W.B. White, ed.), Vol 2. p. 984-990.

Doctor, D.H., Schwartz, B.F., and Gary, M.O. (2009) Preliminary development of a statistically based karst classification system, PHORMS. In: Proceedings of the Fifteenth International Congress of Speleology, July 19-26, 2009, Kerrville, Texas (W.B. White, ed.), vol. 2, p. 843-848.

Tobin, B., and Doctor, D.H. (2009) Estimating karst conduit length using conductivity and discharge measurements in Lilburn Cave, Kings Canyon National Park, California. In: Proceedings of the Fifteenth International Congress of Speleology, July 19-26, 2009, Kerrville, Texas (W.B. White, ed.), Vol. 3, p. 1702-1706.

Doctor, D.H., Orndorff, W., and Orndorff, R.C. (2009) Overview of the Shenandoah Valley karst of Virginia and West Virginia. In: Guidebook for Excursion No.1, Coast to Coast Excursion, Eastern Segment, July 27 to August 5, 2009 (K.W. Stafford and B. Fratesi, eds.), Excursion Guidebook for the Fifteenth International Congress of Speleology of the International Union of Speleology. Greyhound Press: Huntsville, Alabama, p. 84-96. 

Doctor, K.Z. and Doctor, D.H., Kronenfeld, B., Wong, D.W.S., and Brezinski, D.K. (2008) Predicting Sinkhole Susceptibility in Frederick Valley, Maryland, Using Geographically Weighted Regression. In: Sinkholes and the Engineering and Environmental Impacts of Karst (L.B. Yuhr, E.C. Alexander, Jr., and B.F. Beck, eds.), Proceedings of the Eleventh Multidisciplinary Conference, Geotechnical Special Publication no. 183, American Society of Civil Engineers, p.243-256.

Doctor, D.H., Weary, D.J., Epstein, J.B., and Orndorff, R.C. (2008) A Karst Aquifer Map for the United States—Is it possible?: U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, USGS Scientific Investigations Report 2008-5023, p. 34-36.

Doctor D.H. (2008) Hydrologic connections and dynamics of water movement in the Classical Karst (Kras) aquifer: evidence from frequent chemical and stable isotope sampling. Acta Carsologica, vol. 37, no.1, p. 101-123.

Sebestyen, S.D., E.W. Boyer, J.B. Shanley, C. Kendall, D.H. Doctor, G.R. Aiken, and N. Ohte (2008), Sources, transformations, and hydrological processes that control stream nitrate and dissolved organic matter concentrations during snowmelt in an upland forest, Water Resour. Res., 44, W12410, doi:101029/2008WR006983.  

Sebestyen, S.D., E.W. Boyer, J.B. Shanley, C. Kendall, D.H. Doctor, G.R. Aiken, and N. Ohte (2008). Sources, transformations, and hydrological processes that control stream nitrate and dissolved organic matter concentrations during snowmelt in an upland forest, Water Resources Research, 44, W12410, doi:101029/2008WR006983 [Link]

Doctor, D.H., Kendall, C., Sebestyen S.D., Shanley, J.B, Ohte, N., and Boyer, E.W. (2008). Carbon isotope fractionation of dissolved inorganic carbon (DIC) due to outgassing of carbon dioxide from a headwater stream. Hydrological Processes. vol. 22, p. 2410-2423 [Link]

Doctor, D.H., Weary, D.J., Orndorff, Randall C., Harlow, George E., Jr., Kozar, Mark D., Nelms, David L. (2008). Bedrock structural controls on the occurrence of sinkholes and springs in the northern Great Valley karst, Virginia and West Virginia. In: Sinkholes and the Engineering and Environmental Impacts of Karst (L.B. Yuhr, E.C. Alexander, Jr., and B.F. Beck, eds.), Proceedings of the Eleventh Multidisciplinary Conference, Geotechnical Special Publication no. 183, American Society of Civil Engineers, p.12-22

Ohte N., Dahlgren R.A., Silva S.R., Kendall C., Kratzer C.R., Doctor D.H. (2007) Sources and transport of algae and nutrients in a Californian river in a semi-arid climate. Freshwater Biology 52, p. 2476–2493, doi:10.1111/j.1365-2427.2007.01849.x  

Doctor, D.H., Alexander, E.C., Jr., Petric, M., Kogovsek, J., Urbanc, J., Lojen, S., and Stichler, W. (2006) Quantification of karst aquifer discharge components through end-member mixing analysis using natural chemistry and stable isotopes as tracers. Hydrogeology Journal, v. 14, p. 1,171, 1,191 [Link]

Doctor D.H., and Alexander E.C., Jr. (2005) Interpretation of water chemistry and stable isotope data from a karst aquifer according to flow regimes identified through hydrograph recession analysis. U.S. Geological Survey Scientific Investigations Report 2005-5160, p. 82-92 [Link]

Ohte N., Sebestyen S.D., Shanley J.B., Doctor D.H., Kendall C., Wankel S.D., and Boyer E.W. (2004) Tracing sources of nitrate in snowmelt runoff using a high-resolution isotopic technique. Geophysical Research Letters, 31(21), L21506

Doctor, D.H. (2002) The Hydrogeology of the Classical Karst (Kras) Aquifer of Southwestern Slovenia. Ph.D. dissertation, University of Minnesota, Minneapolis, 252 pp.

Doctor, D. (2001) Experiments in mineral dissolution kinetics: a guide to their design and interpretation. Minnesota Department of Natural Resources, Division of Lands and Minerals, Reclamation Section: St. Paul, MN, 20 pp.

Doctor, D., Leopold E., and Lapakko K. (2001) Carbonate mineral dissolution: reaction rates and mechanisms. Minnesota Department of Natural Resources, Division of Lands and Minerals, Reclamation Section: St. Paul, MN, 69 pp.

Phillips, E., Doctor, D., Leopold, E., and Lapakko, K. (2001) Dissolution of silicate minerals present in Duluth Complex and Archean Greenstone formations (Literature Summary) Minnesota Department of Natural Resources, Division of Lands and Minerals, Reclamation Section: St. Paul, MN, 36 pp.

Doctor, D.H., M. Horvat and S. Lojen (2000) A stable isotope investigation of the Classical Karst aquifer: Evaluating karst groundwater components for water quality preservation. Acta Carsologica, vol. 29, no. 1.

Alexander, E. Calvin, Jr., Scott C. Alexander, Sheila R. Grow, Betty J. Wheeler, Roy A. Jameson, Lifeng Guo, and Daniel H. Doctor (1999) Geochemical and isotopic evidence for multiple residence time in the same aquifer, Symposium on Karst Modeling,  February 24-27, 1999, Charlottesville, VA., Karst Modeling, KWI Special Publication 5, Karst Waters Institute.

ABSTRACTS:

Doctor, D.H., Herman, J.S., and Farrar, N.C. (2010) Sources of flow to a spring in a fractured and karstic aquifer: the combined use of artificial and geochemical tracers. Geological Society of America Annual Meeting (31 October –3 November 2010), Denver, Colorado, Abstracts with Programs, Vol. 42, No. 5, p. 328 

Doctor, D.H., Alexander, E.C., Jr., Jameson, R., and Alexander, S.C. (2010) Month-scale residence time of vadose zone storage estimated through hydrologic and geochemical monitoring of cave drip waters, Minnesota, U.S.A. Geological Society of America, North-Central Section (44th Annual) and South-Central Section (44th Annual) Joint Meeting (11–13 April 2010), Abstracts with Programs, Vol. 42, No. 2, p. 78.

Schwartz, B.F., Doctor, D.H., and Gary, M.O. (2010) Quantifiable characteristics for a statistical approach toward karst classification. Geological Society of America North-Central Section (44th Annual) and South-Central Section (44th Annual) Joint Meeting (11–13 April 2010), Abstracts with Programs, Vol. 42, No. 2, p. 76

Farrar, N.C., Doctor, D.H. and Herman, J.S. (2010) Interaction between quick and diffuse flow in a karst aquifer revealed through dye tracing to Fay and Sempeles springs in Winchester, Virginia. Geological Society of America Northeastern Section (45th Annual) and Southeastern Section (59th Annual) Joint Meeting (13-16 March 2010), Abstracts with Programs, Vol. 42, No. 1, p. 156.

Doctor, D.H., Orndorff, W., and Plummer, L.N. (2008) A Proposed Hypogenic Origin of Karst in the Shenandoah Valley, Virginia and West Virginia.  Geological Society of America Abstracts with Programs, Vol. 40, No. 6, p. 341 

Weary, D.J., Doctor, D.H., Epstein, J.B., and Orndorff, R.C. (2008) Characterizing Regional Karst Types Under the Framework of the New National Karst Map: U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, 2008, USGS Scientific Investigations Report 2008-5023, p. 25-33.  

Weary D.J., Doctor D.H., Orndorff R.C., Harlow G.E., Jr (2007) Structural control of spring locations in the northern Shenandoah Valley, Virginia and West Virginia: interpretation of geologic controls on ground-water flow paths in folded and faulted carbonate rocks. Geological Society of America Abstracts with Programs, Vol. 39, No. 2, p. 99.

Doctor, D.H. (2007) Geologic controls on karst aquifer function as reflected in hydrographs and chemographs: relating recession coefficients to flow regimes, chemical loads, and fractal dimensions.Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 516.

Tobin, B.W. and Doctor, D.H. (2007) Estimating karst conduit length using conductivity and discharge measurements in Lilburn Cave, Kings Canyon National Park, California. Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 376.

Doctor, D.H., Sebestyen, S.D., Aiken, G.R., Shanley, J.B., Kendall, C. and Boyer, E.B. (2006) Carbon Isotope Composition as an Indicator of DOC Sources to a Stream During Events in a Temperate Forested Catchment. Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstract B33A-1154

Doctor D.H., Rollog M.E., Silva S.R., Kendall C. (2005) Diel Stable Isotopic Variation of Dissolved Oxygen, Carbon, Nitrate and Particulate Organic Matter in the San Joaquin River, California, Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract H13F-1377.

Doctor D.H., S.R. Silva, C. Kendall, C.C.Y. Chang, J. Hench, and W.E. Fleenor (2005) An Investigation of Low Dissolved Oxygen Conditions in the San Joaquin River Using Stable Isotopic Techniques. Abstract, 7^th Biennial State of the San Francisco Estuary Conference, Oakland, CA, Oct 4-6, 2005.

Doctor D.H., Kendall, C., Sebestyen, S.D., Shanley, J. (2004) Carbon isotopes as tracers of groundwater and soil water contributions to streamflow in a forested headwater catchment. GSA Abstracts with Programs, vol. 36, No.5. Geological Society of America annual meeting, Denver, CO, Nov. 7-10, 2004.

Doctor D.H., Ohte, N., Kendall, C., Silva, S.R. (2004) Carbon isotopes as a tool for investigating sources and carbon cycling in the San Joaquin River. Abstracts: 3rd Biennial CALFED Bay-Delta Program Science Conference, Oct 4-6, 2004 Sacramento, CA.

Doctor D.H. (2003) Using Hydrograph Recession Analysis for Linking Hydrology to Chemistry: A Flow Regime Approach.  Eos Trans. AGU, 84(47), Fall Meet. Suppl., Abstract H42K-02.

Doctor D.H., Sebestyen S.D., Ohte, N., Wankel, S., Shanley, J., and Kendall, C. (2003) Carbon and Nitrogen Isotopes as Indicators of Streamflow Generation Processes: Use of Automated CF-IRMS Analysis Techniques for d¹³C of DIC and DOC and d¹⁵N and d¹⁸O of Nitrate. Presented at the 10th Annual Canadian Continuous-Flow Isotope Ratio Mass Spectrometry (CF-IRMS) Workshop, Aug. 10-13, Winnipeg, Canada.

Doctor D. H., E.C. Alexander, Jr., and W. Stichler (2001) Isotopic tracers do not usurp groundwater chemistry or vice versa: Combined isotopic and chemical tracers in upper Mississippi Valley and Slovenian karst aquifers yield more information than either would alone. EOS, Trans. Amer. Geophys. Union, 2001 Spring Meeting, v. 82, n. 20, May 15, 2001. Supplement, p. S172.

Doctor D., Horvat, M. and Longinelli, A. (1999) An Investigation into the Fate and Transport of Mercury within the Classical Karst, Using Environmental Isotopes as Tracers. V International Conference on Mercury as a Global Pollutant, Rio De Janeiro, May 23 to 28, 1999, Program with abstracts.

Doctor D.H. and Alexander E.C., Jr. (1998) Results of Monitoring the Isotopic Composition and Hydrology of Infiltrating Drip Waters in Mystery Cave, Minnesota. EOS, Trans. Amer. Geophys. Union, 1998 Spring Meeting, v. 79, n. 17, Supplement, April 28, 1998, p. S83-84.

Doctor D.H., M. E. Berndt, W. E. Seyfried, Jr. (1995) An evaluation of near-equilibrium calcite kinetics at 100 degrees C using an isotopic doping technique. Geological Society of America, 1995 annual meeting, Abstracts with Programs - Geological Society of America, 27 (6), p. 249.