ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-8969-2010 A map of radon flux at the Australian land surface Griffiths A. D. 1 Zahorowski W. 1 Element A. 1 Werczynski S. 1 Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia 27 09 2010 10 18 8969 8982 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/8969/2010/acp-10-8969-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/8969/2010/acp-10-8969-2010.pdf

A time-dependent map of radon-222 flux density at the Australian land surface has been constructed with a spatial resolution of 0.05° and temporal resolution of one month. Radon flux density was calculated from a simple model utilising data from national gamma-ray aerial surveys; modelled soil moisture, available from 1900 in near real-time; and maps of soil properties. The model was calibrated against a data set of accumulation chamber measurements, thereby constraining it with experimental data. A notable application of the map is in atmospheric mixing and transport studies which use radon as a tracer, where it is a clear improvement on the common assumption of uniform radon flux density.

 References Antonopoulos-Domis, M., Xanthos, S., Clouvas, A., and Alifrangis, D.: Experimental and theoretical study of radon distribution in soil, Health Phys., 97, 322–331, \doi10.1097/HP.0b013e3181adc157, 2009. Biraud, S., Ciais, P., Ramonet, M., Simmonds, P., Kazan, V., Monfray, P., O'Doherty, S., Spain, T G., and Jennings, S G.: European greenhouse gas emissions estimated from continuous atmospheric measurements and radon 222 at Mace Head, Ireland, J. Geophys. Res., 105(D1), 1351–1366, \doi10.1029/1999JD900821, 2000. Bureau of Rural Sciences: Australian Natural Resources Data Library, online available at: http://adl.brs.gov.au/anrdl/, last access: 28 October 2009. Conen, F. and Robertson, L.: Latitudinal distribution of radon-222 flux from continents, Tellus B, 54, 127–133, \doi10.1034/j.1600-0889.2002.00365.x, 2002. Dickson, B L. and Scott, K M.: Interpretation of aerial gamma-ray surveys – adding the geochemical factors, AGSO J. Aust. Geol. Geophys., 17, 187–200, 1997. Goto, M., Moriizumi, J., Yamazawa, H., Iida, T., and Zhuo, W.: Estimation of global radon exhalation rate distribution, in: The Natural Radiation Environment – 8th International Symposium, edited by: Paschoa, A S., 169–172, Americal Institute of Physics, 2008. Grasty, R L.: Radon emanation and soil moisture effects on airborne gamma-ray measurements, Geophysics, 62, 1379–1385, \doi10.1190/1.1444242, 1997. Greeman, D J. and Rose, A W.: Factors controlling the emanation of radon and thoron in soils of the eastern USA, Chem. Geol., 129, 1–14, \doi10.1016/0009-2541(95)00128-X, 1996. Gupta, M., Douglass, A. R.,~Kawa, S., and Pawson, S.: Use of radon for evaluation of atmospheric transport models: sensitivity to emissions, Tellus B, 56, 404–412, \doi10.1111/j.1600-0889.2004.00124.x, 2004. Hirsch, A. I.: On using radon-222 and CO<sub>2</sub> to calculate regional-scale CO<sub>2</sub> fluxes, Atmos. Chem. Phys., 7, 3737–3747, doi:10.5194/acp-7-3737-2007, 2007. Holford, D J., Schery, S D., Wilson, J L., and Phillips, F M.: Modeling Radon Transport in Dry, Cracked Soil, J. Geophys. Res., 98, 567–580, \doi10.1029/92JB01845, 1993. Hutter, A R. and Knutson, E O.: An international intercomparison of soil gas radon and radon exhalation measurements, Health Phys., 74, 108–114, \doi10.1097/00004032-199801000-00014, 1998. International Atomic Energy Agency: Guidelines for radioelement mapping using gamma ray spectrometry data, IAEA-TECDOC-1363, IAEA, Vienna, 2003. Jacob, D., Prather, M., Rasch, P., Shia, R., Balkanski, Y., Beagley, S., Bergmann, D., Blackshear, W., Brown, M., Chiba, M., et~al.: Evaluation and intercomparison of global atmospheric transport models using $^222$Rn and other short-lived tracers, J. Geophys. Res, 102, 5953–5970, \doi10.1029/96JD02955, 1997. Jones, D A., Wang, W., and Fawcett, R: Climate data for the Australian Water Availability Project Final Milestone Report, National Climate Centre, Australian Bureau of Meteorology, 36~pp., 2007. Lehmann, B E., Lehmann, M., Neftel, A., Gut, A., and Tarakanov, S V.: Radon-220 calibration of near-surface turbulent gas transport, Geophys. Res. Lett., 26, 607–610, 1999. Markkanen, M. and Arvela, H.: Radon Emanation from Soils, Radiat. Prot. Dosim., 45, 269–272, 1992. Mayya, Y S.: Theory of radon exhalation into accumulators placed at the soil-atmosphere interface, Radiat Prot Dosimetry, 111, 305–318, \doi10.1093/rpd/nch346, 2004. McKenzie, N. and Hook, J.: Interpretations of the Atlas of Australian Soils, CSIRO Division of Soils Technical Report, 94, 1992. McKenzie, N., Land, C., and Water: Estimation of Soil Properties Using the Atlas of Australian Soils, Tech. Rep. 11/00, CSIRO, prefixhttp://www.clw.csiro.au/publications/technical2000/ (last access: October 2009), 2000. Minty, B.: Fundamentals of airborne gamma-ray spectrometry, AGSO J. Aust. Geol. Geophys., 17, 39–50, 1997. Minty, B.: Automatic merging of gridded airborne gamma-ray spectrometric surveys, Explor. Geophys., 31, 47–51, \doi10.1071/EG00047, 2000. Minty, B. and Wilford, J.: Radon effects in ground gamma-ray spectrometric surveys, Explor. Geophys., 35, 312–318, \doi10.1071/EG04312, 2004. Minty, B. R S., Franklin, R., Milligan, P R., Richardson, L M., and Wilford, J.: The Radiometric Map of Australia, in: 20th International Geophysical Conference and Exhibition, Australian Society of Exploration Geophysicists, Adelaide, 2009. Nazaroff, W.: Radon transport from soil to air, Rev. Geophys., 30, 137–160, \doi10.1029/92RG00055, 1992. Northcote, K., Beckmann, G., Bettenay, E., Churchward, H., Dijk, D V., Dimmock, G., Hubble, G., Isbell, R., McArthur, W., and Murtha, G.: Atlas of Australian Soils, Sheets 1 to 10, with explanatory data, 1960. Papachristodoulou C, Ioannides K, Spathis S.: The effect of moisture content on radon diffusion through soil: assessment in laboratory and field experiments, Health Phys., 92(3), 257–264, \doi10.1097/01.HP.0000248147.46038.bc, 2007. Raupach, M R., Briggs, P R., Haverd, V., King, E A., Paget, M., and Trudinger, C M.: Australian Water Availability Project, online available at: http://www.csiro.au/awap/, 2008. Raupach, M R., Briggs, P R., Haverd, V., King, E A., Paget, M., and Trudinger, C M.: Australian Water Availability Project (AWAP): CSIRO Marine and Atmospheric Research Component: Final Report for Phase 3, CAWCR technical report, CSIRO, 2009. Rogers, V C. and Nielson, K K.: Correlations for predicting air permeabilities and $^222$Rn diffusion coefficients of soils, Health Phys., 61, 225–230, \doi10.1097/00004032-199108000-00006, 1991. Sakoda, A., Ishimori, Y., Hanamoto, K., Kataoka, T., Kawabe, A., and Yamaoka, K.: Experimental and modeling studies of grain size and moisture content effects on radon emanation, Radiat. Meas., 45, 204–210, \doi10.1016/j.radmeas.2010.01.010, 2010. Sasaki, T., Gunji, Y., and Okuda, T.: Mathematical modeling of Radon emanation, J. Nucl. Sci. Tech., 41, 142–151, \doi10.3327/jnst.41.142, 2004. Schery, S., Gaeddert, D., and Wilkening, M.: Factors affecting exhalation of radon from a gravelly sandy loam, J. Geophys. Res., 89, 7299–7309, \doi10.1029/JD089iD05p07299, 1984. Schery, S., Whittlestone, S., Hart, K., and Hill, S.: The flux of radon and thoron from Australian soils, J. Geophys. Res, 94, 8567–8576, \doi10.1029/JD094iD06p08567, 1989. Schery, S D. and Huang, S.: An estimate of the global distribution of radon emissions from the ocean, Geophys. Res. Lett., 31, L19104, \doi10.1029/2004GL021051, 2004. Schery, S D. and Wasiolek, M A.: Radon and Thoron in the Human Environment, chap. Modeling Radon Flux from the Earth's Surface, 207–217, World Scientific Publishing, World Scientific Publishing, Singapore, 1998. \bibitem[Szegvary et~al.(2007)Szegvary, Leuenberger, and Conen] Szegvary2007 Szegvary, T., Leuenberger, M. C., and Conen, F.: Predicting terrestrial $^222$Rn flux using gamma dose rate as a proxy, Atmos. Chem. Phys., 7, 2789–2795, doi:10.5194/acp-7-2789-2007, 2007. Szegvary, T., Conen, F., and Ciais, P.: European $^222$Rn inventory for applied atmospheric studies, Atmos. Environ., 43, 1536–1539, \doi10.1016/j.atmosenv.2008.11.025, 2009. United States Department of Agriculture: Field book for describing and sampling soils, Version 2.0., Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE, available online at: http://soils.usda.gov/technical/fieldbook/ (last access: October 2008), 2002. Watson, D.: The natural neighbor series manuals and source codes, Comput. Geosci., 25, 463–466, \doi10.1016/S0098-3004(98)00150-2, 1999. Werczynski, S., Conen, F., Zahorowski, W., and Chambers, S.: Comparison of University of Basel and ANSTO emanometers, Tech. rep., ANSTO, in preparation, 2010. Whittlestone, S., Zahorowski, W., and Schery, S.: Radon flux variability with season and location in Tasmania, Australia, J. Radioanal. Nucl. Chem., 236, 213–217, \doi10.1007/BF02386345, 1998. Williams, A., Chambers, S., Zahorowski, W., Crawford, J., Matsumoto, K., and Uematsu, M.: Estimating the Asian radon flux density and its latitudinal gradient in winter using ground-based radon observations at Sado Island, Tellus B, 61, 732–746, \doi10.1111/j.1600-0889.2009.00438.x, 2009. Zahorowski, W. and Whittlestone, S.: A Fast Portable Emanometer for Field Measurement of Radon and Thoron Flux, Radiat. Protect. Dosim., 67, 109–120, 1996. Zahorowski, W., Chambers, S., and Henderson-Sellers, A.: Ground based radon-222 observations and their application to atmospheric studies, J. Environ. Radioact., 76, 3–33, \doi10.1016/j.jenvrad.2004.03.033, 2004. Zhang, K., Wan, H., Zhang, M., and Wang, B.: Evaluation of the atmospheric transport in a GCM using radon measurements: sensitivity to cumulus convection parameterization, Atmos. Chem. Phys., 8, 2811–2832, doi:10.5194/acp-8-2811-2008, 2008. Zhuo, W., Iida, T., and Furukawa, M.: Modeling Radon Flux Density from the Earth's Surface, J. Nucl. Sci. Tech., 43, 479–482, \doi10.3327/jnst.43.479, 2006. Zhuo, W., Guo, Q., Chen, B., and Cheng, G.: Estimating the amount and distribution of radon flux density from the soil surface in China, J. Environ. Radioact., 99, 1143–1148, \doi10.1016/j.jenvrad.2008.01.011, 2008.