Distribution and sources of 226 Ra in groundwater of arid region M. J. Zheng 1 • A. Murad 2 • X. D. Zhou 1,3 • P. Yi 1,3 • D. Alshamsi 2 • S. Hussein 2 • L. Chen 3,4 • X. L. Hou 5,6 • A. Aldahan 2 • Z. B. Yu 1,3 Received: 2 September 2015 Ó Akade ´miai Kiado ´, Budapest, Hungary 2015 Abstract As a part of characterizing radioactivity in groundwater of the eastern Arabian Peninsula, a first sys- tematic evaluation of 226 Ra activity in groundwater indi- cates a wide range (0.65–203.66 mBq L -1 ) with average of 17.56 mBq L -1 . Adsorption/desorption process, ground- water residence time and uranium concentration are the main controlling factors of 226 Ra distribution in ground- water of the different aquifers. Estimation of 226 Ra effec- tive dose from water ingestion suggests potential risk of drinking water from the carbonate aquifer. Keywords 226 Ra Á Groundwater Á Radioactivity Á Health hazard Introduction Characterizing the quality and radioactivity of groundwater in arid and semiarid climate regions is becoming essential issue for further development as groundwater represents the main source of water in such regions. 226 Ra (half-life 1620 years) is a natural decay product of 238 U and a parent nuclide for 222 Rn. The occurrence of these isotopes in groundwater in relatively high concentrations can be a source of environmental hazard. 226 Ra may enter the groundwater by a number of processes like alpha-recoil, desorption–adsorption and ion exchange [1]. The 226 Ra along with 222 Rn and 228 Ra are expected to give highest contribution to the effective dose from ingestion of water [2–4]. The relatively long-lasting (a lifetime) residence of 226 Ra in human bones means that high activity in drinking water and food represents serious health hazard. Accord- ingly, different dose conversion coefficients for different age groups were recommended by the ICRP for the public [5]. The higher dose conversion coefficient of 226 Ra for infants and adolescents compared to adults indicates that internal dose may exceed the individual dose criterion (IDC) of 0.1 mSv year -1 [6]. Therefore, knowledge of local and regional distributions of 226 Ra and its sources in groundwater of arid regions will assist decision makers to manage and regulate this water resource in term of drinking quality. A case study of 226 Ra distribution in arid region is presented here from the eastern region of the Arabian Peninsula, namely from the United Arab Emirate (UAE). The region is located in arid to semi-arid climate regime with large dependence on groundwater as natural water resource. Efforts are therefore focused on conservation strategies where groundwater represents a prime target and has been widely used for the domestic and agricultural Electronic supplementary material The online version of this article (doi:10.1007/s10967-015-4632-1) contains supplementary material, which is available to authorized users. & P. Yi pengyi1915@163.com 1 College of Hydrology and Water Resources, Hohai University, Nanjing, China 2 Department of Geology, United Arab Emirates University, Al Ain, United Arab Emirates 3 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China 4 Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV 89119, USA 5 Center for Nuclear Technologies, Technical University of Denmark, 4000 Roskilde, Denmark 6 Xi’an AMS Centre and SKLLQG Institute of Earth Environment, CAS, Xi’an 710075, China 123 J Radioanal Nucl Chem DOI 10.1007/s10967-015-4632-1