Advertisement

Environmental Science and Pollution Research

, Volume 26, Issue 3, pp 2328–2344 | Cite as

Sources and distribution of 241Am in the vicinity of a deep geologic repository

  • Punam ThakurEmail author
  • Anderson L. Ward
Research Article
  • 27 Downloads

Abstract

The detection, distribution, and long-term behavior of 241Am in the terrestrial environment at the Waste Isolation Pilot Plant (WIPP) site were assessed using historical data from an independent monitoring program conducted by the Carlsbad Environmental Monitoring & Research Center (CEMRC), and its predecessor organization the Environmental Evaluation Group (EEG). An analysis of historical data indicates frequent detections of trace levels of 241Am in the WIPP environment. Positive detections and peaks in 241Am concentrations in ambient air samples generally occur during the March to June timeframe, which is when strong and gusty winds in the area frequently give rise to blowing dust. A study of long-term measurements of 241Am in the WIPP environment suggest that the resuspension of previously contaminated soils is likely the primary source of americium in the ambient air samples from WIPP and its vicinity. Furthermore, the 241Am/239 + 240Pu ratio in aerosols and soils was reasonably consistent from year to year and was in agreement with the global fallout ratios. Higher than normal activity concentrations of 241Am and 241Am/239 + 240Pu ratios were measured in aerosol samples during 2014 as a result of February 14, 2014 radiation release event from the WIPP underground. However, after a brief spike, the activity concentrations of 241Am have returned to the normal background levels. The long-term monitoring data suggest there is no persistent contamination and no lasting increase in radiological contaminants in the region that can be considered significant by any health-based standard.

Keywords

Americium WIPP site Aerosol Resuspension Soil Depth distribution 

Notes

Acknowledgements

This research is supported by grant from US Department of Energy, Carlsbad Field Office of DOE through Grant No. DE-EM 0002423. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors.

References

  1. Aarkrog A (1988a) Studies of Chernobyl debris in Denmark. Environ Int 14:149–155CrossRefGoogle Scholar
  2. Aarkrog A (1988b) The radiological impact of the Chernobyl debris compared with that from nuclear weapons fallout. J Environ Radioact 6:151–162CrossRefGoogle Scholar
  3. Aarkrog A, Dahlgaard H, Nilsson K (1984) Further studies of plutonium and americium at Thule, Greenland. Health Phys 46:29–44CrossRefGoogle Scholar
  4. Alvarado JAC, Steinmann P, Estier S, Bochud F, Haldimann M, Froidevaux P (2014) Anthropogenic radionuclides in atmospheric air over Switzerland during the last few decades. Nature Com 5:3030.  https://doi.org/10.1038/ncomms4030 CrossRefGoogle Scholar
  5. Anspaugh LR, Shinn JH, Phelps PL, Kennedy NC (1975) Resuspension and redistribution of plutonium in soils. Health Phys 29:571–582CrossRefGoogle Scholar
  6. Eberhart CF (1998) Ambient air sampling for radioactive air contaminants at Los Alamos National Laboratory: A large research and development facility. LA-UR-98-897, Los Alamos National Laboratory, Los Alamos, NMGoogle Scholar
  7. Arimoto R, Webb JL, Conley M (2005) Radioactive contamination of atmospheric dust over southeastern New Mexico. Atom Environ 39:4745–4754CrossRefGoogle Scholar
  8. Arnold D, Wershofen H (2000) Plutonium isotopes in ground-level air in Northern Germany since 1990. J Radioanal Nucl Chem 243:409–413CrossRefGoogle Scholar
  9. Baskaran M, Asbill S, Santschi P, Davis T, Brooks J, Champ M, Makeyev V, Khlebovich V (1995) Distribution of 239,240Pu and 238Pu concentrations in sediments from the Ob and Yenisey Rivers and the Kara Sea. Appl Radiat Isot 46(11):1109–1119CrossRefGoogle Scholar
  10. Beasley TM, Kelley JM, Orlandini KA, Bond LA, Aarkrog A, Trapeznikov AP, Pozolotina VN (1998) Isotopic Pu, U, and Np signatures in soils from Semipalatinsk-21, Kazakh Republic and the southern Urals, Russia. J Environ Radioact 39:215–230CrossRefGoogle Scholar
  11. Bennett B.G (1979). Environmental aspects of americium. Rep. EML-348, Environmental Measurements Laboratory, U.S. Department of Energy, New York, New YorkGoogle Scholar
  12. Boulyga SF, Zoriy M, Michael E, Ketterer ME, Becker JS (2003) Depth profiling of Pu, 241Am and 137Cs in soils from southern Belarus measured by ICP-MS and α and γ spectrometry. J Environ Monit 5:661–666CrossRefGoogle Scholar
  13. Breban DC, Moreno J, Mocanu N (2003) Activities of Pu radionuclides and 241Am in soil samples from an alpine pasture in Romania. J Radioanal Nucl Chem 258:613–617CrossRefGoogle Scholar
  14. Bunzl K, Kracke W (1988) Cumulative deposition of 137Cs, 238Pu, 239+240Pu and 241Am from global fallout in soils from forest, grassland and arable land in Bavaria (FRG). J Environ Radioact 8:1–14CrossRefGoogle Scholar
  15. Burns PA, Cooper MB, Lokan KH, Wilks MJ, Williams GA (1995) Characteristics of plutonium and americium contamination at the former UK atomic weapons test ranges at Maralinga and Emu. Appl Radiat Isot 46:1099–1107CrossRefGoogle Scholar
  16. Carlsbad Environmental Monitoring and Research Center (CEMRC) (1998) 1997 Report Carlsbad Environmental Monitoring & Research Center Waste-management Education & Research Consortium (WERC), New Mexico State University, Carlsbad, NM.Google Scholar
  17. Carlsbad Environmental Monitoring and Research Center (CEMRC) (2006) Annual report. New Mexico State University, Carlsbad, NMGoogle Scholar
  18. Carlsbad Environmental Monitoring and Research Center (CEMRC) (2014) Annual report. New Mexico State University, Carlsbad, NMGoogle Scholar
  19. Cooper MB, Burns PA, Tracy BL, Wilks MJ, Williams GA (1994) Characterization of plutonium contamination at the former nuclear weapons testing range, at Maralinga in South Australia. J Radioanal Nucl Chem 177:161–184CrossRefGoogle Scholar
  20. Dares CJ, Lapides AM, Mincher BJ, Meyer TJ (2015) Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode. Science 350:652–655CrossRefGoogle Scholar
  21. EPA (1976) Americium - Its behavior in soil and plant systems. Las Vegas, NV: Office of Research and Development, U.S. Environmental Protection Agency. EPA600/3-76-005. PB250797Google Scholar
  22. Eriksson M, Lindahl P, Roos P, Dahlgaard, H, Holm, E (2008) U, Pu, and Am nuclear signatures of the Thule hydrogen bomb debris. Environ Sci Technol 42:4717–4722Google Scholar
  23. Evangeliou N, Zibtsev S, Myroniuk V, Zhurba M, Hamburger T, Stohl A, Balkanski Y, Paugam R, Mousseau TA, Møller AP, Kireev SI (2016) Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: an impact assessment. Sci Rep 6:26062.  https://doi.org/10.1038/srep26062. CrossRefGoogle Scholar
  24. Faller F (1994) Residual soil radioactivity at the gnome test site in Eddy County, New Mexico, report no. EPA 600/R-94/117, July 1994. Washington, DC, Environmental Protection AgencyGoogle Scholar
  25. Gray DH, Kenney JW, Ballard SC (2000) Operational Radiation Surveillance of the WIPP Project by EEG During 1999. EEG-79, Environmental Evaluation Group, AlbuquerqueGoogle Scholar
  26. Guogang J, Testa C, Desideri D, Roselli C (1998) Sequential separation and determination of plutonium, americium-241 and strontium-90 in soils and sediments. J Radioanal Nucl Chem 230:21–27CrossRefGoogle Scholar
  27. Hardy EP, Krey PW, Volchok HL (1973) Global inventory and distribution of fallout plutonium. Nature 241:444–445CrossRefGoogle Scholar
  28. Hindman FD (1986) Actinide separations for alpha spectrometry using neodymium fluoride coprecipitation. Anal Chem 56:1238–1241CrossRefGoogle Scholar
  29. Hirose K, Igarashi Y, Aoyama M, Kim CK, Kim CS, Chang BW (2003) Recent trends of plutonium fallout observed in Japan: plutonium as a proxy for desertification. J Environ Monit 5:302–307CrossRefGoogle Scholar
  30. Hirose K, Kim CK, Kim CS, Chang BW, Igarashi Y, Aoyama M (2004) Wet and dry deposition patterns of plutonium in Daejeon, Korea. Sci Total Environ 332:243–252CrossRefGoogle Scholar
  31. Hodge V, Smith C, Whiting J (1996) Radiocesium and plutonium: still together in “background” soils after more than thirty years. Chemosphere 32:2067–2075CrossRefGoogle Scholar
  32. Holgye Z, Schlesingerova E, Tecl J, Filgas R (2004) 238Pu and 239+240Pu, 241Am, 90Sr and 137Cs in the soils around nuclear research center REZ, near Prague. J Environ Radioact 71:115–125CrossRefGoogle Scholar
  33. Holgye Z, Filgas R (1987) Determination of 239+240Pu in surface air in several localities in Czechoslovakia in 1986 in connection with the Chernobyl radiation accident. J Radioanal Nucl Chem 119:21–28CrossRefGoogle Scholar
  34. Hollander W (1994) Resuspension factors of 137Cs in Hannover after the Chernobyl accident. J Aerosol Sci 25:789–792CrossRefGoogle Scholar
  35. Hulse SE, Ibrahim SA, Whicker FW, Chapman PL (1999) Comparison of 241Am, 239,240Pu and 137Cs concentrations in soil around rocky flats. Health Phys 76:275–287CrossRefGoogle Scholar
  36. Hayes RB, Akbarzadeh M (2014) Using isotopic ratios for discrimination of environmental anthropogenic radioactivity. Health Phys 107:277–291CrossRefGoogle Scholar
  37. Irlweck K, Hrnecek E (1999) 241Am concentration and 241Pu/239(240) Pu ratios in soils contaminated by weapons-grade plutonium. J Radioanal Nucl Chem 242:595–599CrossRefGoogle Scholar
  38. Irlweck K, Wicke J (1998) Isotopic composition of plutonium immissions in Austria after the Chernobyl accident. J Radioanal Nucl Chem 227:133–136CrossRefGoogle Scholar
  39. Jia C, Testa C, Desideri D, Guerra F, Roselli MA, Belli ME (1999) Soil concentration, vertical distribution and inventory of plutonium, 241Am, 90Sr and 137Cs in the Merche region of Central Italy. Health Phys 77:52–61CrossRefGoogle Scholar
  40. Kenney JW, Downes PS, Gray DH, Ballard SC (1995) Radionuclide baseline in soil near project gnome and the waste isolation pilot plant. EEG-58, Environmental Evaluation Group, Albuquerque, NMGoogle Scholar
  41. Knatko VA, Mayall A, Drugachenok MA, Matveenko II, Mironov VP (1993) Radiation doses in southern Byelorussia from the inhalation of specific radionuclides following the Chernobyl accident. Radiat Prot Dosim 48:179–183Google Scholar
  42. Krey PW, Hardy EP, Pachucki C, Rourke F, Coluzza J, Benson WK (1976) Mass isotopic composition of global fallout plutonium in soil. Transuranic nuclides in the environment. IAEA-SM-199/39. Vienna: IAEA, p. 671–678.Google Scholar
  43. Lee MH, Clark S (2005). Activities of Pu and Am isotopes and isotopic ratios in a soil contaminated by weapons-grade plutonium, 39: 5512–5516Google Scholar
  44. Lee SC, Orlandini KA, Webb J, Schoep D, Kirchner T, Fingleton DJ (1998) Measurement of baseline atmospheric plutonium-239, 240 and americium-241 in the vicinity of the waste isolation pilot plant. J Radioanal Nucl Chem 234:267–272CrossRefGoogle Scholar
  45. Lehto J, Salminen S, Jaakkola T, Outola I, Pulli S, Paatero J, Tarvainen M, Ristonmaa S, Zilliacus R, Ossintsev A, Larin V (2006) Plutonium in the air in Kurchatov, Kazakhstan. Sci Total Environ 366:206–217CrossRefGoogle Scholar
  46. Lemons B, Khaing H, Ward A, Thakur P (2018) A rapid method for the sequential separation of polonium, plutonium, americium and uranium in drinking water. Appl Radiat Isot 136:10–17.CrossRefGoogle Scholar
  47. Leon Vintro L, Mitchell PI, Condren OM, Downes AB, Papucci C, Delfanti R (1999) Vertical and horizontal fluxes of plutonium and americium in the western Mediterranean and the Strait of Gibraltar. Sci Total Environ 237/238:77–91CrossRefGoogle Scholar
  48. Litaor MI (1995) Spatial analysis of plutonium-239+ 240 and americium-241 in soils around Rocky Flats, Colorado. J Environ Qual 24:506–516CrossRefGoogle Scholar
  49. Litaor M, Allen LA (1996) Comprehensive appraisal of 241Am in soils around Rocky Flats, Colorado. Health Phys 71:347–357CrossRefGoogle Scholar
  50. Livens FR, Singleton DL (1991) Plutonium and americium in soil organic matter. J Environ Radioact 13:323–339CrossRefGoogle Scholar
  51. Łokas EJW, Mietelski JW, Ketterer ME, Kleszcz K, Wachniew P, Michalska S, Miecznik M (2013) Sources and vertical distribution of 137Cs, 238Pu, 239+240Pu and 241Am in peat profiles from southwest Spitsbergen. Appl Geochem 28:100–108CrossRefGoogle Scholar
  52. Lujanienė G, Aninkevičius V, Lujanas V (2009) Artificial radionuclides in the atmosphere over Lithuania. J Environ Radioact 100:108–119Google Scholar
  53. Lujaniené G, Valiulis D, Bycenkiene S, Sakalys J, Povinec PP (2012a) Plutonium isotopes and 241Am in the atmosphere of Lithuania: a comparison of different source terms. Atmos Environ 61:419–427CrossRefGoogle Scholar
  54. Lujaniené G, Bycenkiene S, Povinec PP, Gera M (2012b) Radionuclides from the Fukushima accident in the air over Lithuania e measurement and modeling approaches. J Environ Radioact 114:71–80CrossRefGoogle Scholar
  55. Lujaniene G, Sapolaite J, Remeikis V, Lujanas V, Jermolajev A (2006) Cesium, americium and plutonium isotopes in ground level air of Vilnius. Czech J Phys Suppl D 56:D55–D66CrossRefGoogle Scholar
  56. Lujaniene G, Lujanas V, Jankunaite D, Ogorodnikov BI, Mastauskas A, Ladygiene R (1999) Speciation of radionuclides of the Chernobyl origin in aerosol and soil samples. J Environ Radioact 49:107–114Google Scholar
  57. Manić-Kudra S, Paligorić D, Novković D, Smiljanić R, Milošević Z, Subotić K (1995) Plutonium isotopes in the surface air at Vinča-Belgrade site in May 1986. J Radioanal Nucl Chem 199:27–34CrossRefGoogle Scholar
  58. Mboulou MO, Hurtgen C, Hofkens K, Vandecasteele C (1998) Vertical distributions in the Kapachi soil of the plutonium isotopes (238Pu, 239,240Pu, 241Pu), of 241Am, and of 243,244Cm, eight years after the Chernobyl accident. J Environ Radioact 39:231–237CrossRefGoogle Scholar
  59. Menut L, Masson O, Bessagnet B (2009) Contribution of Saharan dust on radionuclide aerosol activity levels in Europe? The 21-22 February 2004 case study. J Geophys Res 114:D16202CrossRefGoogle Scholar
  60. Mietelski JW, Kubica B, Gaca P, Tomankiewicz E, Blazej S, Tuteja-Krysa M, Stobiski M (2007) 238Pu, 239+240Pu, 241Am, 90Sr and 137Cs in mountain soil samples from the Tatra National Park (Poland). J Radioanal Nucl Chem 275:523–533CrossRefGoogle Scholar
  61. Muramatsu Y, Hamilton T, Uchida S, Tagami K, Yoshida S, Robison W (2001) Measurement of 240Pu/239Pu isotopic ratios in soils from the Marshall Islands using ICP-MS. Sci Total Environ 278:151–159CrossRefGoogle Scholar
  62. Paatero J, Hameri K, Jaakkola T, Jantunen M, Koivukoski J, Saxen R (2010) Airborne and deposited radioactivity from the Chernobyl accident—a review of investigations in Finland Boreal. Environ Res 15:19–33Google Scholar
  63. Perkins RW, Thomas CW (1980) Worldwide fallout. In: Hanson WC (ed) Transuranic elements in the environment. Technical Information Center, US Dept of Energy, Springfield, pp 53–82.Google Scholar
  64. Pham MK, Chamizo E, Balbuena JLM, Juan-Carlos Miquel JC, Martín J, Osvath I, Pavel P, Povinec PP (2017) Impact of Saharan dust events on radionuclide levels in Monaco air and in the water column of the northwest Mediterranean Sea. J Environ Radioact 166:2–19CrossRefGoogle Scholar
  65. Poet SE, Martell EA (1972) Plutonium-239 and americium-241contamination in the Denver area. Health Phys 23:537–548CrossRefGoogle Scholar
  66. Popov L, Mihailova G, Naidenov I (2010) Determination of activity ratios of 238, 239+240, 241Pu, 241Am 134, 137Cs and 90Sr in Bulgarian soils. J Radioanal Nucl Chem 285:223–237CrossRefGoogle Scholar
  67. Poston TM, Hanf RW, Dirkes RL and Morasch LF (2002) Hanford site environmental report for calendar year 2000. PNNL-13910, Pacific Northwest National Laboratory, RichlandGoogle Scholar
  68. Price RR (1991) The depth distribution of 90Sr, 137Cs, and 239,240Pu in soil profile samples. Radiochim Acta 54:145–147CrossRefGoogle Scholar
  69. Reiter ER (1975) Stratospheric-tropospheric exchange processes. Rev Geophys Space Phys 4:459–474CrossRefGoogle Scholar
  70. Roos P, Holm E, Persson RBR, Aarkrog A, Nielsen SP (1994) Deposition of 210Pb, 137Cs, 239+240Pu, 238Pu, and 241Am in the Antarctic Peninsula area. J Environ Radioact 24:235–251CrossRefGoogle Scholar
  71. Salminen S, Paatero J (2009) Concentrations of 238Pu, 239+240Pu and 241Pu in the surface air in Finnish Lapland in 1963. Boreal Environ Res 14:827–836Google Scholar
  72. Sehmel GA (1987) Transuranic resuspension. In: Pinter JE III, Alberts JJ, McLeod KW, Schreckhise RG (eds) Environmental research on actinide elements. Office of Science and Technical Information; CONF-841142, Washington, DC, pp 157–192Google Scholar
  73. Sha L, Yamamoto M, Kumura K, Ueno K (1991) 239+240Pu, 241Am and 137Cs in soils from several areas in China. J Radioanal Nucl Chem Lett 155:45–53CrossRefGoogle Scholar
  74. Shinn JH, Homan DN, Robison WL (1997) Resuspension studies in the Marshall Islands. Health Phys 73:248–257CrossRefGoogle Scholar
  75. Shinonaga T, Steier P, Lagos M, Ohkura T (2014) Airborne plutonium and non-natural uranium from the Fukushima DNPP found at 120 km distance a few days after reactor hydrogen explosions. Environ Sci Technol 48:3808–3814CrossRefGoogle Scholar
  76. Solovitch-Vella N, Pourcelot L, Chen VT, Froidevaux P, Gauthier-Lafaye F, Stille P, Aubert D (2007) Comparative migration behavior of Sr-90, Pu-239+240 and Am-241 in mineral and organic soils of France. Appl Geochem 22:2526–2535CrossRefGoogle Scholar
  77. Srncik M, Wallner G, Hrnecek E, Steier P, Wallner A, Bossew P (2008) Vertical distribution of 238Pu, 239(40)Pu, 241Am, 90Sr and 137Cs in Austrian soil profiles. Radiochim Acta 96:733–738CrossRefGoogle Scholar
  78. Stout JE, Arimoto R (2010) Threshold wind velocities for sand movement in the Mescalero Sands of southeastern New Mexico. J Arid Environ 74:1456–1460CrossRefGoogle Scholar
  79. Thakur P, Ballard S, Nelson R (2012) Plutonium in the WIPP environment: its detection, distribution and behavior. J Environ Monit 14:1604–1615CrossRefGoogle Scholar
  80. Thakur P, Lemons BG, White CR (2016) The magnitude and relevance of the February 2014 radiation release from the waste isolation pilot plant repository in New Mexico, USA. Sci Total Environ 565:1124–1137CrossRefGoogle Scholar
  81. Thurston J (2010) NCRP Report No. 160: ionizing radiation exposure of the population of the United States, National Council on Radiation Protection and Measurements, BethesdaGoogle Scholar
  82. Turner M, Rudin M, Cizdziel J, Hodge V (2003) Excess plutonium in soil near the Nevada Test Site, USA. Environ Pollut 125:193–203CrossRefGoogle Scholar
  83. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000, Sources and effects of ionizing radiation, Report to the General Assembly, with Scientific Annexes Vol. I United Nations, New YorkGoogle Scholar
  84. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 1982, Sources and effects of ionizing radiation, Report to the General Assembly, Annexe E. United Nations, New York.Google Scholar
  85. USAEC (1973) Gnome/Coach site disposal options. U.S. Atomic Energy Commission NVO-131, Las Vegas, NVGoogle Scholar
  86. USDOE (2014) Title 40 CFR Part 191 Subparts B and C Compliance Recertification Application 2014.DOE/WIPP-14-3503. SOTERM-III. Appendix SOTERM-2014.Google Scholar
  87. USDOE (2015). U.S. Department of Energy Accident Investigation Report, Phase-II. Radiological Release Event at the Waste Isolation Pilot Plant on February 14, 2014. Washington, DC: U.S. Department of Energy. Accessible at: http://www.wipp.energy.gov/Special/AIB_WIPP%20Rad_Event%20Report_Phase%20II.pdfGoogle Scholar
  88. USDOE (1995) Geochemical characterization of background surface soils: background soils characterization program. Rocky Flats Environmental Technology Site, Golden COGoogle Scholar
  89. USDOE (2014) Waste Isolation Pilot Plant Annual Site Environmental Report for 2014. DOE/WIPP-15-8866, Carlsbad Field Office, CarlsbadGoogle Scholar
  90. Wang Z, Yang G, Zheng J, Cao L, Yu H, Zhu Y, Tagami K, Uchida S (2015) Effect of ashing temperature on accurate determination of plutonium in soil samples. Anal Chem 87:5511–5515CrossRefGoogle Scholar
  91. Welch JM, Mgller D, Knoll C, Wilkovitsch M, Giester G, Ofner J, Lendl B, Weinberger P, Georg Steinhauser G (2017) Picomolar traces of americium(III) introduce drastic changes in the structural chemistry of terbium(III): a break in the “gadolinium break”. Angew Chem Int Ed 56:13264–13269CrossRefGoogle Scholar
  92. WIPP Land Withdrawal Act (Public Law 102-579). The Waste Isolation Pilot Plant Land Withdrawal Act as amended by public law 104-201 (H.R. 3230, 104th congress).Google Scholar
  93. Wotawa G, De Geer L-E, Becker A, D’Amours R, Jean M, Servranckx R, Ungar K (2006) Inter- and intra-continental transport of radioactive cesium released by boreal forest fires. Geophys Res Lett 33:L12806CrossRefGoogle Scholar
  94. Yamamoto M, Komura K, Sakanoue M (1983) 241Am and plutonium in Japanese rice-field surface soils. J Radiat Res 24:237–249CrossRefGoogle Scholar
  95. Yamamoto M, Tsukatani T, Katayama Y (1996) Residual radioactivity in the soil of the Semipalatinsk-21 Nuclear Test Site in the former USSR. Health Phys 71:142–148CrossRefGoogle Scholar
  96. Yammoto M, Tsumura A, Katayama Y, Tsukatani T (1996) Plutonium isotopic composition in soil from the former Semipalatinsk Nuclear Test Site. Radiochim Acta 72:209–215Google Scholar

Copyright information

© This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2018

Authors and Affiliations

  1. 1.Carlsbad Environmental Monitoring & Research CenterCarlsbadUSA
  2. 2.U.S. Department of Energy, Carlsbad Field OfficeCarlsbadUSA

Personalised recommendations