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Energy and Environment Directorate

Nik Qafoku

Nik Qafoku

Pacific Northwest National Laboratory
PO Box 999
Richland, WA 99352
(509) 371-6089

Biography

Nik Qafoku is a chief scientist and team lead in the Interfacial Geochemistry Team of the Subsurface Science and Technology Group. He received the B.S. degree and the Doctor of Science degree in soil fertility and soil chemistry from the College of Agronomy and Environmental Sciences of the Agricultural University of Tirana, Albania. He served as assistant pedagogue, pedagogue, department head and vice-dean for research of this College. He was then nominated director of the science, research and training directorate of the Department of Agriculture and Food and supervised the research conducted in the research institutes and stations in Albania.

In 1994 he was awarded a Senior Fulbright Scholarship and conducted soil systems modeling work at Virginia Polytechnic Institute and State University. Later that year, he was accepted in the graduate school of the University of Georgia where he studied environmental soil science, applied math and computer science. He graduated in 1998 finishing a double-degree program (M.S. in Applied Mathematics and Computer Sciences and Ph.D. in Environmental Soil Chemistry and Physics). He served as a teaching assistant and received the outstanding graduate teaching award from the University of Georgia. He worked as a postdoctoral research associate from 1999-2000 at the University of Georgia, and joined the PNNL in June of 2000 initially as a postdoctoral researcher. Since then, Nik has been promoted three times to the categories of research scientist, senior research scientist level III and IV and chief scientist level V.

Research Interests

  • Transport-controlled mobilization and immobilization of contaminants in heterogeneous environments
  • Elemental cycling in soils and sediments
  • Changes in aquifer geochemistry and contaminant behavior in aquifers exposed to leaking CO2 gas from deep subsurface storage
  • Waste form performance and interactions in different environments

Education and Credentials

  • Ph.D. December 1998, Environmental Soil Chemistry, University of Georgia, Athens, GA
  • M.S. December 1998, Computer Science&Applied Mathematics, University of Georgia, Athens, GA
  • Doctor of Science June 1990, Soil Science, Agricultural University of Tirana, Albania
  • B.S. June 1984, Agronomy, Agricultural University of Tirana, Albania

Affiliations and Professional Service

  • American Chemical Society (since 2001; membership number: 2305157)
  • International Union of Soil Science (since 1994; membership number: 312-37130)
  • Soil Science Society of America (since 1994; membership number: 86341)
  • Geochemical Society of America (since 2001)  
  • American Geophysical Union (since 2002; membership number: 30086002)
  • The Clay Minerals Society (2004-2007; membership number: 300279)

Awards and Recognitions

  • Senior Fulbright Scholar (1994)
  • Outstanding Teaching Assistant Award, University of Georgia (1998)
  • Outstanding Performance Awards, PNNL (2005, 2007 and 2009)
  • Citation of excellence award for associate editor of the Soil Science Society of America Journal (2009)
  • Exceptional Contribution Award, PNNL (2014)
  • EED Paper of Year Award, PNNL (2015)
  • Exceptional Contribution Award, PNNL (2016)
  • EED Paper of Year Award, PNNL (2016)
  • R&D 100 Award (2017)

PNNL Publications

2018

  • Asmussen R.M., C.I. Pearce, B.W. Miller, A.R. Lawter, J.J. Neeway, W.W. Lukens, and M.E. Bowden, et al. 2018. "Getters for Improved Technetium Containment in Cementitious Waste Forms." Journal of Hazardous Materials 341. PNNL-SA-123813. doi:10.1016/j.jhazmat.2017.07.055
  • Demirkanli D.I., M.J. Truex, J.E. Szecsody, M. Snyder, J.J. Moran, M.K. Nims, and A.R. Lawter, et al. 2018. Contaminant Attenuation and Transport Characterization of 200-DV-1 Operable Unit Sediment Samples from Boreholes C9497, C9498, C9603, C9488, and C9513. PNNL-27524. Richland, WA: Pacific Northwest National Laboratory.
  • Kerisit S.N., F.N. Smith, M.E. Hoover, S.A. Saslow, and N. Qafoku. 2018. "Incorporation Modes of Iodate in Calcite." Environmental Science & Technology 52, no. 10:5902-5910. PNNL-SA-129924. doi:10.1021/acs.est.8b00339
  • Lawter A.R., N. Qafoku, R.M. Asmussen, R.K. Kukkadapu, O. Qafoku, D.H. Bacon, and C.F. Brown. 2018. "Element mobilization and immobilization from carbonate rocks between CO2 storage reservoirs and the overlying aquifers during a potential CO2 leakage." Chemosphere 197. PNNL-SA-125304. doi:10.1016/j.chemosphere.2017.12.199
  • Qafoku N., C.E. Bagwell, A.R. Lawter, M.J. Truex, J.E. Szecsody, O. Qafoku, and L. Kovarik, et al. 2018. Conceptual Model of Subsurface Processes for Iodine at the Hanford Site. PNNL-28053. Richland, WA: Pacific Northwest National Laboratory.

2017

  • Hufschmid R.D., C.J. Newcomb, J.W. Grate, J.J. De Yoreo, N.D. Browning, and N. Qafoku. 2017. "Direct visualization of aggregate morphology and dynamics in a model soil organic-mineral system." Environmental Science & Technology Letters 4, no. 5:186-191. PNNL-SA-124132. doi:10.1021/acs.estlett.7b00068
  • Lee B.D., J.E. Szecsody, N. Qafoku, E.M. McElroy, S.R. Baum, M. Snyder, and A.R. Lawter, et al. 2017. Contaminant Attenuation and Transport Characterization of 200-UP-1 Operable Unit Sediment Samples. PNNL-26894. Richland, WA: Pacific Northwest National Laboratory.
  • Newcomb C.J., N. Qafoku, J.W. Grate, V.L. Bailey, and J.J. De Yoreo. 2017. "Developing a Molecular Picture of Soil Organic Matter-Mineral Interactions by Quantifying Organo-Mineral Binding." Nature Communications 8. PNNL-SA-121086. doi:10.1038/s41467-017-00407-9
  • Qafoku N., A.R. Lawter, D.H. Bacon, L. Zheng, J.E. Kyle, and C.F. Brown. 2017. "Review of the Impacts of Leaking CO2 Gas and Brine on Groundwater Quality"." Earth - Science Reviews 169. PNNL-SA-119041. doi:10.1016/j.earscirev.2017.04.010
  • Strickland C.E., A.R. Lawter, N. Qafoku, J.E. Szecsody, M.J. Truex, and G. Wang. 2017. Evaluation of Iodine Remediation Technologies in Subsurface Sediments: Interim Status Report. PNNL-26957. Richland, WA: Pacific Northwest National Laboratory.
  • Strickland C.E., C.D. Johnson, B.D. Lee, N. Qafoku, J.E. Szecsody, M.J. Truex, and V.R. Vermeul. 2017. Identification of Promising Remediation Technologies for Iodine in the UP-1 Operable Unit. PNNL-26934. Richland, WA: Pacific Northwest National Laboratory.
  • Szecsody J.E., B.D. Lee, A.R. Lawter, N. Qafoku, C.T. Resch, S.R. Baum, and I.I. Leavy, et al. 2017. Effect of Co-Contaminants Uranium and Nitrate on Iodine Remediation. PNNL-26955. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., B.D. Lee, C.D. Johnson, N. Qafoku, J.E. Szecsody, J.E. Kyle, and M.M. Tfaily, et al. 2017. Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site. PNNL-24709 Rev. 2. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., J.E. Szecsody, N. Qafoku, C.E. Strickland, J.J. Moran, B.D. Lee, and M. Snyder, et al. 2017. Contaminant Attenuation and Transport Characterization of 200-DV-1 Operable Unit Sediment Samples. PNNL-26208; RPT-DVZ-AFRI-037. Richland, WA: Pacific Northwest National Laboratory.
  • Xu J., H. Veeramani, N. Qafoku, G. Singh, M.V. Riquelme Breazeal, A. Pruden, and R.K. Kukkadapu, et al. 2017. "Efficacy of Acetate-Amended Biostimulation for Uranium Sequestration: Combined Analysis of Sediment/Groundwater Geochemistry and Bacterial Community Structure." Applied Geochemistry 78. PNNL-SA-120349. doi:10.1016/j.apgeochem.2016.12.024
  • Xu J., H. Veeramani, N. Qafoku, G. Singh, M.V. Riquelme Breazeal, A. Pruden, and R.K. Kukkadapu, et al. 2017. "Efficacy of Acetate-Amended Biostimulation for Uranium Sequestration: Combined Analysis of Sediment/Groundwater Geochemistry and Bacterial Community Structure." Applied Geochemistry 78. PNNL-SA-123123. doi:10.1016/j.apgeochem.2016.12.024

2016

  • Andersen A., P.N. Reardon, S.S. Chacon, N. Qafoku, N.M. Washton, and M. Kleber. 2016. "Protein-mineral Interactions: Molecular Dynamics Simulations Capture Importance of Variations in Mineral Surface Composition and Structure." Langmuir 32, no. 24:6194-6209. PNNL-SA-116971. doi:10.1021/acs.langmuir.6b01198
  • Asmussen R.M., C.I. Pearce, A.R. Lawter, J.J. Neeway, B.L. Miller, B.D. Lee, and N.M. Washton, et al. 2016. Getter Incorporation into Cast Stone and Solid State Characterizations. PNNL-25577 Rev. 0;RPT-SLAW-003 Rev A. Richland, WA: Pacific Northwest National Laboratory.
  • Asmussen R.M., J.J. Neeway, A.R. Lawter, A.D. Wilson, and N. Qafoku. 2016. "Silver Based Getters for 129-I Removal from Low Activity Wastes." Radiochimica Acta 104, no. 12:905-913. PNNL-SA-116202. doi:10.1515/ract-2016-2598
  • Asmussen R.M., J.J. Neeway, A.R. Lawter, T.G. Levitskaia, W.W. Lukens, and N. Qafoku. 2016. "The Function of Sn(II)-Apatite as a 99-Tc Immobilizing Agent." Journal of Nuclear Materials 480. PNNL-SA-114465. doi:10.1016/j.jnucmat.2016.09.002
  • Bacon D.H., N. Qafoku, Z. Dai, E. Keating, and C.F. Brown. 2016. "Modeling the Impact of Carbon Dioxide Leakage into an Unconfined, Oxidizing Carbonate Aquifer." International Journal of Greenhouse Gas Control 44, no. 2016:290-299. PNNL-SA-105184. doi:10.1016/j.ijggc.2015.04.008
  • Gartman B.N., and N. Qafoku. 2016. "Uranium interaction with soil minerals in the presence of co-contaminants: Case Study- subsurface sediments at or below the water table." In Trace Elements in Waterlogged Soils and Sediments. Advances in Trace Elements in the Environment, edited by J Rinklebe, AS Knox and M Paller. 225-249. Boca Raton, Florida:CRC Press. PNNL-SA-103897.
  • Harvey O.R., N. Qafoku, K.J. Cantrell, M.J. Wilkins, and C.F. Brown. 2016. "Methanogenesis-induced pH-Eh shifts drives aqueous metal(loid) mobility in sulfide mineral systems under CO2 enriched conditions." Geochimica et Cosmochimica Acta 173. PNNL-SA-105773. doi:10.1016/j.gca.2015.11.002
  • Neeway J.J., N. Qafoku, B.D. Williams, M. Snyder, C.F. Brown, and E.M. Pierce. 2016. "Evidence of Technetium and Iodine from a Sodalite-Bearing Ceramic Waste Form." Applied Geochemistry 66. PNNL-SA-101989. doi:10.1016/j.apgeochem.2015.12.017
  • Neeway J.J., R.M. Asmussen, A.R. Lawter, M.E. Bowden, W.W. Lukens, D. Sarma, and B.J. Riley, et al. 2016. "Removal of TcO4- from Representative Nuclear Waste Streams with Layered Potassium Metal Sulfide Materials." Chemistry of Materials 28, no. 11:3976-3983. PNNL-SA-116928. doi:10.1021/acs.chemmater.6b01296
  • Qafoku N., and J.E. Amonette. 2016. "Iron Oxides." In Encyclopedia of Soil Science. 3rd Edition, edited by Rattan Lal. 1245-1249. Boca Raton, Florida:Taylor & Francis Group. PNNL-SA-110804.
  • Qafoku N., and R. Sahajpal. 2016. "Subsoil contaminant Cr fate and transport: The complex reality of the Hanford subsurface." In Trace Elements in Waterlogged Soils and Sediments. Advances in Trace Elements in the Environment, edited by J Rinklebe, AS Knox and M Paller. 163-183. Boca Raton, Florida:CRC Press. PNNL-SA-114768.
  • Van Ranst E., N. Qafoku, A. Noble, and R. Xu. 2016. "VARIABLE CHARGE SOILS: MINERALOGY AND CHEMISTRY." In Encyclopedia of Soil Science, edited by Rattan Lal. 2432-2439. Boca Raton, Florida:Taylor & Francis Group. PNNL-SA-110721.
  • Williams B.D., J.J. Neeway, M. Snyder, M.E. Bowden, J.E. Amonette, B.W. Arey, and E.M. Pierce, et al. 2016. "Mineral Assemblage Transformation of a Metakaolin-based Waste Form After Geopolymer Encapsulation." Journal of Nuclear Materials 473. PNNL-SA-98733. doi:10.1016/j.jnucmat.2015.12.023
  • Xu R., N. Qafoku, E. Van Ranst, J. Li, and J. Jiang. 2016. "Adsorption properties of subtropical and tropical variable charge soils: Implications from climate change and biochar amendment." In Advances in Agronomy. 1-58. Amsterdam, :Elsevier. PNNL-SA-113468. doi:10.1016/bs.agron.2015.09.001

2015

  • Gartman B.N., N. Qafoku, J.E. Szecsody, R.K. Kukkadapu, Z. Wang, D.M. Wellman, and M.J. Truex. 2015. "Uranium Fate in Hanford Sediment Altered by Simulated Acid Waste Solutions." Applied Geochemistry 63, no. December 2015:1-9. PNNL-SA-105743. doi:10.1016/j.apgeochem.2015.07.010
  • Last G.V., M. Snyder, W. Um, J.R. Stephenson, I.I. Leavy, C.E. Strickland, and D.H. Bacon, et al. 2015. Technetium, Iodine, and Chromium Adsorption/Desorption Kd Values for Vadose Zone Pore Water, ILAW Glass, and Cast Stone Leachates Contacting an IDF Sand Sequence. PNNL-24683. Richland, WA: Pacific Northwest National Laboratory.
  • Lawter A.R., N. Qafoku, G. Wang, H. Shao, and C.F. Brown. 2015. "Evaluating Impacts of CO2 Intrusion into an Unconsolidated Aquifer: I. Experimental Data." International Journal of Greenhouse Gas Control 44, no. 2016:323-333. PNNL-SA-107057. doi:10.1016/j.ijggc.2015.07.009
  • Lawter A.R., N. Qafoku, H. Shao, D.H. Bacon, and C.F. Brown. 2015. "Evaluating Impacts of CO2 and CH4 Gas Intrusion into an Unconsolidated Aquifer: Fate of As and Cd." Frontiers in Environmental Science 3. PNNL-SA-110137. doi:10.3389/fenvs.2015.00049
  • Mouser P.J., A.L. N'Guessan, N. Qafoku, M. Sinha, K.H. Williams, M. Dangelmayr, and C.T. Resch, et al. 2015. "Influence of Carbon and Microbial Community Priming on the Attenuation of Uranium in a Contaminated Floodplain Aquifer." Ground Water 53, no. 4:600-613. PNNL-SA-99197. doi:10.1111/gwat.12238
  • Neeway J.J., A.R. Lawter, R.J. Serne, R.M. Asmussen, and N. Qafoku. 2015. "Technetium Getters to Improve Cast Stone Performance." In MRS Proceedings: Scientific Basis for Nuclear Waste Management XXXVIII, edited by S Gin, R Jubin, J Matyas and E Vance, 1744, 43-52. Warrendale, Pennsylvania:Materials Research Society. PNNL-SA-106863. doi:10.1557/opl.2015.310
  • Neeway J.J., N. Qafoku, R.J. Serne, A.R. Lawter, J.R. Stephenson, W.W. Lukens, and J.H. Westsik. 2015. Evaluation of Technetium Getters to Improve the Performance of Cast Stone. PNNL-23667 Rev. 1;EMSP-RPT-026 Rev1. Richland, WA: Pacific Northwest National Laboratory.
  • Qafoku N. 2015. "Climate-change effects on soils: Accelerated weathering, soil carbon and elemental cycling." In Advances in Agronomy, edited by DL Sparks. 111-172. Amsterdam:Elsevier. PNNL-SA-102998.
  • Qafoku N., J.J. Neeway, A.R. Lawter, T.G. Levitskaia, R.J. Serne, J.H. Westsik, and M. Snyder. 2015. Technetium and Iodine Getters to Improve Cast Stone Performance. PNNL-23282 Rev. 1. Richland, WA: Pacific Northwest National Laboratory.
  • Qafoku N., L. Zheng, D.H. Bacon, A.R. Lawter, and C.F. Brown. 2015. A Critical Review of the Impacts of Leaking CO2 Gas and Brine on Groundwater Quality. PNNL-24897. Richland, WA: Pacific Northwest National Laboratory.
  • Reiser J.T., L. Neill, J.L. Weaver, B. Parruzot, C. Musa, J.J. Neeway, and J.V. Ryan, et al. 2015. "Glass corrosion in the presence of iron-bearing materials and potential corrosion suppressors." In Scientific Basis for Nuclear Waste Management XXXVIII. MRS Proceedings, edited by S Gin, R Jubin, J Matyas and E Vance, 1744, 139-144. Cambridge:Materials Research Society. PNNL-SA-108398. doi:10.1557/opl.2015.503
  • Shao H., N. Qafoku, A.R. Lawter, M.E. Bowden, and C.F. Brown. 2015. "Coupled Geochemical Impacts of Leaking CO2 and Contaminants from Subsurface Storage Reservoirs on Groundwater Quality." Environmental Science & Technology 49, no. 13:8202-8209. PNNL-SA-108351. doi:10.1021/acs.est.5b01004
  • Szecsody J.E., M.J. Truex, L. Zhong, J.P. McKinley, N. Qafoku, B.D. Lee, and S.D. Saurey. 2015. "Remediation of Technetium in Vadose Zone Sediments Using Ammonia and Hydrogen Sulfide Gases." Vadose Zone Journal 14, no. 7. PNNL-SA-107578. doi:10.2136/vzj2014.09.0134
  • Truex M.J., B.D. Lee, C.D. Johnson, N. Qafoku, G.V. Last, M.H. Lee, and D.I. Kaplan. 2015. Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site. PNNL-24709. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., J.E. Szecsody, N. Qafoku, R. Sahajpal, L. Zhong, A.R. Lawter, and B.D. Lee. 2015. Assessment of Hexavalent Chromium Natural Attenuation for the Hanford Site 100 Area. PNNL-24705. Richland, WA: Pacific Northwest National Laboratory.
  • Wang G., N. Qafoku, A.R. Lawter, M.E. Bowden, O. Harvey, E.C. Sullivan, and C.F. Brown. 2015. "Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to an Unconfined Oxidizing Carbonate Aquifer." International Journal of Greenhouse Gas Control 44, no. 2016:310-322. PNNL-SA-96349. doi:10.1016/j.ijggc.2015.07.002
  • Zheng L., N. Qafoku, A.R. Lawter, G. Wang, H. Shao, and C.F. Brown. 2015. "Evaluating Impacts of CO2 Intrusion into an Unconsolidated Aquifer: II. Modeling Results." International Journal of Greenhouse Gas Control 44, no. 2016:300-309. PNNL-SA-106872. doi:10.1016/j.ijggc.2015.07.001

2014

  • Namgung S., M. Kwon, N. Qafoku, and G. Lee. 2014. "Cr(OH)3(s) Oxidation Induced by Surface Catalyzed Mn(II) Oxidation." Environmental Science & Technology 48, no. 18:10760-10768. PNNL-SA-101626. doi:10.1021/es503018u
  • Neeway J.J., E.M. Pierce, V.L. Freedman, J.V. Ryan, and N. Qafoku. 2014. A Strategy to Conduct an Analysis of the Long-Term Performance of Low-Activity Waste Glass in a Shallow Subsurface Disposal System at Hanford. PNNL-23503; RPT-66309-001 Rev. 0. Richland, WA: Pacific Northwest National Laboratory.
  • Neeway J.J., N. Qafoku, B.D. Williams, K.A. Rod, M.E. Bowden, C.F. Brown, and E.M. Pierce. 2014. "Performance of the Fluidized Bed Steam Reforming Product Under Hydraulically Unsaturated Conditions." Journal of Environmental Radioactivity 131. PNNL-SA-96489. doi:10.1016/j.jenvrad.2013.10.008
  • Qafoku N. 2014. Overview of different aspects of climate change effects on soils. PNNL-23483. Richland, WA: Pacific Northwest National Laboratory.
  • Qafoku N., A.R. Lawter, H. Shao, G. Wang, and C.F. Brown. 2014. "Evaluating impacts of CO2 gas intrusion into a confined sandstone aquifer: Experimental results." Energy Procedia 63. PNNL-SA-105260. doi:10.1016/j.egypro.2014.11.355
  • Qafoku N., B.N. Gartman, R.K. Kukkadapu, B.W. Arey, K.H. Williams, P.J. Mouser, and S.M. Heald, et al. 2014. "Geochemical and Mineralogical Investigation of Uranium in Multi-element Contaminated, Organic-rich Subsurface Sediment." Applied Geochemistry 42. PNNL-SA-86519. doi:10.1016/j.apgeochem.2013.12.001
  • Qafoku N., J.J. Neeway, A.R. Lawter, T.G. Levitskaia, R.J. Serne, J.H. Westsik, and M. Snyder. 2014. Technetium and Iodine Getters to Improve Cast Stone Performance. PNNL-23282. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., J.E. Szecsody, L. Zhong, and N. Qafoku. 2014. Gas-Phase Treatment of Technetium in the Vadose Zone at the Hanford Site Central Plateau. PNNL-23665; RPT-DVZ-AFRI-023. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., J.E. Szecsody, N. Qafoku, and R.J. Serne. 2014. Conceptual Model of Uranium in the Vadose Zone for Acidic and Alkaline Wastes Discharged at the Hanford Site Central Plateau. PNNL-23666; RPT-DVZ-AFRI-024. Richland, WA: Pacific Northwest National Laboratory.
  • Truex M.J., V.R. Vermeul, N. Qafoku, and B.D. Lee. 2014. Sampling Instruction: 100-D-100 and 100-D-30/104 Excavation Sites. PNNL-23542. Richland, WA: Pacific Northwest National Laboratory.
  • Westsik J.H., K.J. Cantrell, R.J. Serne, and N. Qafoku. 2014. Technetium Immobilization Forms Literature Survey. PNNL-23329; EMSP-RPT-023. Richland, WA: Pacific Northwest National Laboratory.

2013

  • Harvey O.R., N. Qafoku, K.J. Cantrell, G. Lee, J.E. Amonette, and C.F. Brown. 2013. "Geochemical Implications of Gas Leakage Associated with Geologic CO2 Storage - A Qualitative Review." Environmental Science & Technology 47, no. 1:23-36. PNNL-SA-83207. doi:10.1021/es3029457
  • Neeway J.J., N. Qafoku, C.F. Brown, and R.A. Peterson. 2013. "Characterization and Leaching Tests of the Fluidized Bed Steam Reforming (FBSR) Waste Form for LAW Immobilization." In Proceedings of the Annual Waste Management Symposium (WM2013): International Collaboration and Continuous Improvement, February 24-28, 2013, Phoenix, Arizona, 3, 2268-2275, Paper No. 13400. Tucson, Arizona:WM Symposia. PNNL-SA-91992.
  • Qafoku N., C.F. Brown, G. Wang, E.C. Sullivan, A.R. Lawter, O.R. Harvey, and M. Bowden. 2013. Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to Unconfined and Confined Aquifers. PNNL-22420. Richland, WA: Pacific Northwest National Laboratory.
  • Szecsody J.E., M.J. Truex, N. Qafoku, D.M. Wellman, C.T. Resch, and L. Zhong. 2013. "Influence of Acidic and Alkaline Waste Solution Properties on Uranium Migration in Subsurface Sediments." Journal of Contaminant Hydrology 151. PNNL-SA-96107. doi:10.1016/j.jconhyd.2013.05.009
  • Veeramani H., H. Veeramani, A. Scheinost, N. Monsegue, N. Qafoku, R.K. Kukkadapu, and M. Newville, et al. 2013. "Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite." Environmental Science & Technology 47, no. 5:2361-2369. PNNL-SA-91214. doi:10.1021/es304025x

2012

  • Campbell K.M., R.K. Kukkadapu, N. Qafoku, A.D. Peacock, E. Lesher, K.H. Williams, and J.R. Bargar, et al. 2012. "Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer." Applied Geochemistry 27, no. 8:1499-1511. PNNL-SA-85044. doi:10.1016/j.apgeochem.2012.04.013
  • Harvey O.R., N. Qafoku, K.J. Cantrell, and C.F. Brown. 2012. Geochemical Implications of CO2 Leakage Associated with Geologic Storage: A Review. PNNL-21550. Richland, WA: Pacific Northwest National Laboratory.
  • Neeway J.J., N. Qafoku, B.D. Williams, M.M. Valenta, E.A. Cordova, S.C. Strandquist, and D.C. Dage, et al. 2012. "Single Pass Flow-Through (SPFT) Test Results of Fluidized Bed Steam Reforming (FBSR) Waste Forms used for LAW Immobilization." In Waste Management Symposium (WM 2012): Improving the Future in Waste Management, February 26 - March 1, 2012, Phoenix, Arizona, Paper No. 12252. Tucson, Arizona:Waste Management Symposia, Inc. PNNL-SA-84289.
  • Neeway J.J., N. Qafoku, J.H. Westsik, C.F. Brown, C. Jantzen, and E.M. Pierce. 2012. "Radionuclide and contaminant immobilization in the fluidized bed steam reforming waste products." In Radioactive Waste, edited by RA Rahman. 239-262. Rijeka:InTech Europe. PNNL-SA-83289.
  • Qafoku N. 2012. "Impacts of Environmental Nanoparticles on Chemical, Biological and Hydrological Processes in Terrestrial Ecosystems." In Handbook of Soil Sciences: Resource Management and Environmental Impacts, 2nd Edition, edited by PM Huang, Y Li and ME Sumner. 4.1- 4.17. Boca Raton, Florida:CRC Press. PNNL-SA-69713.
  • Szecsody J.E., M.J. Truex, L. Zhong, T.C. Johnson, N. Qafoku, M.D. Williams, and W.J. Greenwood, et al. 2012. "Geochemical and Geophysical Changes during Ammonia Gas Treatment of Vadose Zone Sediments for Uranium Remediation." Vadose Zone Journal 11, no. 4. PNNL-SA-86840. doi:10.2136/vzj2011.0158
  • Um W., H. Chang, J.P. Icenhower, W.W. Lukens, R.J. Serne, N. Qafoku, and R.K. Kukkadapu, et al. 2012. "Iron Oxide Waste Form for Stabilizing 99Tc." Journal of Nuclear Materials 429, no. 1-3:201-209. PNNL-SA-86045. doi:10.1016/j.jnucmat.2012.06.004
  • Wang G., R.J. Serne, M.J. Lindberg, W. Um, B.N. Bjornstad, B.D. Williams, and I.V. Kutynakov, et al. 2012. Uranium in Hanford Site 300 Area: Extraction Data on Borehole Sediments. PNNL-22032. Richland, WA: Pacific Northwest National Laboratory.

2011

  • Qafoku N., J.H. Westsik, D.M. Strachan, M.M. Valenta, and R.P. Pires. 2011. Secondary Waste Form Down-Selection Data Package-Fluidized Bed Steam Reforming Waste Form. PNNL-20704. Richland, WA: Pacific Northwest National Laboratory.
  • Qafoku N., P.E. Dresel, J.P. McKinley, E.S. Ilton, W. Um, C.T. Resch, and R.K. Kukkadapu, et al. 2011. Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site - Part 2. PNNL-17865. Richland, WA: Pacific Northwest National Laboratory.
  • Um W., H. Chang, J.P. Icenhower, W.W. Lukens, R.J. Serne, N. Qafoku, and J.H. Westsik, et al. 2011. "Immobilization of 99-Technetium (VII) by Fe(II)-Goethite and Limited Reoxidation." Environmental Science & Technology 45, no. 11:4904-4913. PNNL-SA-72463. doi:10.1021/es104343p

2010

  • Cabrera M.L., D.E. Kissel, J.R. Craig, N. Qafoku, N. Vaio, J.A. Rema, and L.A. Morris. 2010. "Relative Humidity Controls Ammonia Loss from Urea Applied to Loblolly Pine." Soil Science Society of America Journal 74, no. 2:543-549. PNNL-SA-69712.
  • Icenhower J.P., N. Qafoku, J.M. Zachara, and W.J. Martin. 2010. "The Biogeochemistry of Technetium: A review of the behavior of an artificial element in the natural environment." American Journal of Science Vol. 310, no. 8:721-752. PNNL-SA-74548. doi:10.2475/08.2010.02
  • Kukkadapu R.K., N. Qafoku, B.W. Arey, C.T. Resch, and P.E. Long. 2010. "Effect of Extent of Natural Subsurface Bioreduction on Fe-mineralogy of Subsurface Sediments." Journal of Physics: Conference Series 217, no. 1:012047 1-8. PNNL-SA-69002. doi:10.1088/1742-6596/217/1/012047
  • Pierce E.M., S.V. Mattigod, J.H. Westsik, R.J. Serne, J.P. Icenhower, R.D. Scheele, and W. Um, et al. 2010. Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams. PNNL-19122. Richland, WA: Pacific Northwest National Laboratory.
  • Qafoku N. 2010. "Terrestrial nanoparticles and their controls on soil/geo processes and reactions." In Advances in Agronomy, edited by Donald Sparks. 33-91. San Diego, California:Academic Press. PNNL-SA-71573.
  • Qafoku N., P.E. Dresel, E.S. Ilton, J.P. McKinley, and C.T. Resch. 2010. "Chromium transport in an acidic waste contaminated subsurface medium: The role of reduction." Chemosphere 81, no. 11:1492-1500. PNNL-SA-71074. doi:10.1016/j.chemosphere.2010.08.043
  • Szecsody J.E., M.J. Truex, L. Zhong, N. Qafoku, M.D. Williams, J.P. McKinley, and Z. Wang, et al. 2010. Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments. PNNL-20004. Richland, WA: Pacific Northwest National Laboratory.
  • Szecsody J.E., V.R. Vermeul, J.S. Fruchter, M.D. Williams, M.L. Rockhold, N. Qafoku, and J.L. Phillips. 2010. Hanford 100-N Area In Situ Apatite and Phosphate Emplacement by Groundwater and Jet Injection: Geochemical and Physical Core Analysis. PNNL-19524. Richland, WA: Pacific Northwest National Laboratory.
  • Um W., H. Chang, J.P. Icenhower, N. Qafoku, S.C. Smith, R.J. Serne, and E.C. Buck, et al. 2010. Immobilization and Limited Reoxidation of Technetium-99 by Fe(II)-Goethite. PNNL-19833. Richland, WA: Pacific Northwest National Laboratory.

2009

  • Fiantis D., M. Nelson, E. Van Ranst, J. Shamshudin, and N. Qafoku. 2009. "Chemical Weathering of New Pyroclastic Deposits from Mt. Merapi (Java), Indonesia." Journal of Mountain Science 6, no. 3:240-254. PNNL-SA-68135.
  • Qafoku N., L. Zhong, C.J. Thompson, C. Liu, B.W. Arey, A.V. Mitroshkov, and R.G. Riley. 2009. "Physical control on CCl4 and CHCl3 desorption from artificially contaminated and aged sediments with supercritical carbon dioxide." Chemosphere 74, no. 4:494-500. PNNL-SA-60227.
  • Qafoku N., P.E. Dresel, J.P. McKinley, C. Liu, S.M. Heald, C.C. Ainsworth, and J.L. Phillips, et al. 2009. "Pathways of aqueous Cr(VI) attenuation in a slightly alkaline oxic subsurface." Environmental Science & Technology 43, no. 4:1071-1077. PNNL-SA-62386.
  • Qafoku N., R.K. Kukkadapu, J.P. McKinley, B.W. Arey, S.D. Kelly, C.M. Wang, and C.T. Resch, et al. 2009. "Uranium in Framboidal Pyrite from a Naturally Bioreduced Alluvial Sediment." Environmental Science & Technology 43, no. 22:8528-8534. PNNL-SA-65650. doi:10.1021/es9017333
  • Zhong L., N. Qafoku, J.E. Szecsody, P.E. Dresel, and Z.F. Zhang. 2009. "Foam Delivery of Calcium Polysulfide to Vadose Zone for Chromium-VI Immobilization: A Laboratory Evaluation." Vadose Zone Journal 8, no. 4:976-985. PNNL-SA-60896. doi:10.2136/vzj2008.0124

2008

  • Dresel P.E., N. Qafoku, J.P. McKinley, J.S. Fruchter, C.C. Ainsworth, C. Liu, and E.S. Ilton, et al. 2008. Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site. PNNL-17674. Richland, WA: Pacific Northwest National Laboratory.
  • Icenhower J.P., N. Qafoku, W.J. Martin, and J.M. Zachara. 2008. The Geochemistry of Technetium: A Summary of the Behavior of an Artificial Element in the Natural Environment. PNNL-18139. Richland, WA: Pacific Northwest National Laboratory.
  • Ilton E.S., N. Qafoku, C. Liu, D.A. Moore, and J.M. Zachara. 2008. "Advective Removal of Intraparticle Uranium from Contaminated Vadose Zone Sediments, Hanford, USA." Environmental Science & Technology 42, no. 5:1565-1571. PNNL-SA-52135. doi:10.1021/es071113m
  • Liu C., J.M. Zachara, N. Qafoku, and Z. Wang. 2008. "Scale-dependent desorption of uranium from contaminated subsurface sediments." Water Resources Research 44. PNNL-SA-56814. doi:10.1029/2007WR006478
  • Qafoku N., and J.P. Icenhower. 2008. "Interactions of Aqueous U(VI) with Soil Minerals in Slightly Alkaline Natural Systems." Re/views in Environmental Science and Bio/technology 7, no. 4:355-380. PNNL-SA-58096. doi:10.1007/s11157-008-9137-8
  • Van Ranst E., S.R. Utami, A. Verdoodt, A. Verdoodt, and N. Qafoku. 2008. "Mineralogy of a perudic Andosol in central Java, Indonesia." Geoderma 144. PNNL-SA-58368.
  • Wellman D.M., J.M. Zachara, C. Liu, N. Qafoku, S.C. Smith, and S.W. Forrester. 2008. "Advective Desorption of Uranium (VI) from Contaminated Hanford Vadose Zone Sediments under Saturated and Unsaturated Conditions." Vadose Zone Journal 7, no. 4:1144-1159. PNNL-SA-60268. doi:10.2136/vzj2007.0166

2007

  • Qafoku N., C.C. Ainsworth, and S.M. Heald. 2007. "Cr(VI) Fate in Mineralogically Altered Sediments by Hyperalkaline Waste Fluids." Soil Science 172, no. 8:598-613. PNNL-SA-52078.
  • Qafoku N., O. Qafoku, C.C. Ainsworth, A. Dohnalkova, and S.G. McKinley. 2007. "Fe-Solid Phase Transformations Under Highly Basic Conditions." Applied Geochemistry 22, no. 9:2054-2064. PNNL-SA-51570. doi:10.1016/j.apgeochem.2007.04.023

2005

  • Qafoku N., J.M. Zachara, C. Liu, P.L. Gassman, O. Qafoku, and S.C. Smith. 2005. "Kinetic Desorption and Sorption of U(VI) During Reactive Transport in a Contaminated Hanford Sediment." Environmental Science & Technology 39, no. 9:3157-3165. PNNL-SA-42960. doi:10.1021/es048462q
  • Qafoku N., M.E. Sumner, and M. Toma. 2005. "Ion Transport Dynamics in Acid Variable Charge Subsoils." Soil Science and Plant Nutrition 51, no. 5:601-603. PNNL-SA-44875.
  • Zachara J.M., J.A. Davis, C. Liu, J.P. McKinley, N. Qafoku, D.M. Wellman, and S.B. Yabusaki. 2005. Uranium Geochemistry in Vadose Zone and Aquifer Sediments from the 300 Area Uranium Plume. PNNL-15121. Richland, WA: Pacific Northwest National Laboratory.

2004

  • Qafoku N., C.C. Ainsworth, J.E. Szecsody, and O. Qafoku. 2004. "Transport-controlled kinetics of dissolution and precipitation in the sediments under alkaline and saline conditions." Geochimica et Cosmochimica Acta 68, no. 14:2981-2995. PNNL-SA-38913.
  • Qafoku N., E. Van Ranst, A. Noble, and G. Baert. 2004. "Variable Charge Soils: Their Mineralogy, Chemistry and Management." In Advances in Agronomy, edited by Donald L. Sparks. 159-215. San Diego, California:Academic Press. PNWD-SA-6396.

2003

  • Qafoku N., C.C. Ainsworth, J.E. Szecsody, and O. Qafoku. 2003. "Aluminum Effect on Dissolution and Precipitation under Hyperalkaline Conditions: I. Liquid Phase Transformations." Journal of Environmental Quality 32, no. 6:2354-2369. PNNL-SA-36190.
  • Qafoku N., C.C. Ainsworth, J.E. Szecsody, D.L. Bish, J.S. Young, D.E. McCready, and O. Qafoku. 2003. "Aluminum Effect on Dissolution and Precipitation under Hyperalkaline Conditions: II. solid Phase Transformations." Journal of Environmental Quality 32, no. 6:2364-2372. PNNL-SA-36191.
  • Qafoku N., C.C. Ainsworth, J.E. Szecsody, O. Qafoku, and S.M. Heald. 2003. "Effect of Coupled Dissolution and Redox Reactions on Cr(VI)(aq) Attenuation during Transport in the Sediments under Hyperalkaline Conditions." Environmental Science & Technology 37, no. 16:3640-3646. PNNL-SA-36318.
  • Qafoku N., E. Van Ranst, A. Noble, and G. Baert. 2003. "Variable Charge Soils: Mineralogy and Chemistry." In Encyclopedia of Soil Science, edited by Rattan Lal. 1822 - 1829. Oxford:Taylor and Francis Group. PNWD-SA-5861.

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