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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.
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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.
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. (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.
Schwartz, B. F. and Doctor, D.H. (2009) Geomorphic and hydrogeologic evolution of karst in the
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.
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 isotopes as tracers. Hydrogeology Journal 14(7): 1171-1191.
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.
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, 7th 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.
My Science Topics
My USGS Science Strategy AreasClimate Variability & Change
A Water Census of the United States
A National Hazard, Risk, and Resilience Assessment Program
Karst geology and hydrology
PRIMARY RESEARCH INTERESTS
Karst (geology, hydrology, geomorphology, speleology, paleoclimatic records)
Geologic mapping in the Appalachians
Biogeochemistry of streams and rivers (carbon and nitrogen cycling)
Applications of stable isotopes as tracers in hydrogeology
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