Abstract
A fractionation of uranium (U) series into parent–daughter pairs – 234U and 238U – always occurs in natural waters, and the disequilibria between these is commonly used as a tracer of groundwater flow. We report here an interpretation of the U-content and U isotope disequilibria in groundwater sampled from the deep Complexe Terminal and Continental Intercalaire aquifers of southern Tunisia. Variations in both the contents of these isotopes (0.006–2.4 ppb) and 234U/238U activity ratios (ARs) (1.7–15.4) were observed. The data could be plotted in two distinct fields of reciprocal U concentration versus 234U/238U AR according to groundwater flow and regional bedrock differences. An initial assessment aimed at verifying whether the results of this investigation support those of previous hydrogeological and isotope studies, thereby suggesting that the disequilibrium between U isotopes in groundwater may represent a useful tool for hydrogeological investigations of deep and fossil groundwater. In addition, the disequilibrium can be used for quantifying the recharge or mixing rates between different formations with the aim of delineating the preferential outflow pattern or determining residence times of waters.
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References
Aranyossy JF, Mamou A (1986) Apport des techniques nucléaires à l’étude des aquifères du Sud tunisien. Projet RAF/8/007. IAEA, Vienna
Banner LJ, Wasserburg GJ, Chen JH, Humphrey JD (1991) Uranium series evidence on diagenesis and hydrology in Pleistocene carbonates of Barbados, West Indies. Earth Planet Sci Lett 107:129–137
Bonotto DM (1999) Applicability of the uranium isotopic model as a prospecting technique in Guarany aquifer, South America. In: 9th Annual VM Goldschmidt Conf, abstr. 7021, LPI contribution no. 971. Lunar and Planetary Institute, Houston
Chakroun I (2003) Utilisation des isotopes de l’uranium pour la caractérisation des aquifères profonds anciens. DEA Géologie, Faculty of Sciences, Sfax, Tunisia
Chen JH, Edwards RL, Wasserburg GJ (1986) 238U, 234U and 232Th in seawater. Earth Planet Sci Lett 80:241–251
Cherdyntsev VV (1955) Uranium series disequilibrium dating In: Trans. 3rd Sess. Commission for determining the absolute Age of Geological Formations. Akad Nauk SSSR 175–182
Dabous A, Osmond JC (2001) Uranium isotopic study of artesian and pluvial contributions to the Nubian aquifer, Western Desert, Egypt. J Hydrol 242: 242–253
Edmunds WM, Shand P, Guendouz AH, Moulla AS, Mamou A, Zouari K (1997) Recharge characteristics and groundwater quality of the Grand Erg Oriental basin. In: Avicennes, technical report WD/97/46R, hydrogeology series. British Geological Survey, Keyworth, UK
ERESS (1972) Etude des ressources en eau du Sahara Septentrional. UNESCO, Paris
Gascoyne M (1992) Geochemistry of the actinides and their daughters, Chap 2. In: Ivanovich M, Harmon RS (eds) Uranium-series disequilibrium; applications to earth, marine, and environmental sciences. Clarendon Press, Oxford, pp 34–61
Gonfiantini R, Conrad G, Fontes JC, Sauzy G, Payne BR (1974) Etude isotopique de la nappe du Continental Intercalaire et ses relations avec les autres nappes du Sahara Septentrional, IAEA-SM-182/25 In: Isotope techniques in groundwater hydrology, vol I. IAEA, Vienna, pp 227–241
Gries S (2000) Etude isotopique et géochimique des nappes profondes au Sahara-Sahel – Implications pour la gestion des ressources en eau et les reconstitutions paléoclimatiques. PhD thesis, University of Paris XI, Faculty of Sciences Orsay, Paris
Kramer TF, Kharaka YK (1986) Uranium geochemistry in US Gulf coast geopressured-geothermal system. Geochim Cosmochim Acta 50:1233–1238
Kronfeld J, Dradsztan E, Müller HW, Radin J, Yaniv A, Zach R (1975) Excess 234U: an aging effect in confined water. Earth Planet Sci Lett 27:189–196
Ku TL, Knauss KG, Mathieu GG (1977) Uranium in open ocean: concentration and isotopic composition. Deep Sea Res 24:1005–1007
Langmuir D (1978) Uranium solution–mineral equilibria at low temperatures with applications to sedimentary ore deposits. Geochim Cosmochim Acta 42:547–569
Mamou A (1990) Caractéristiques, Evaluation, Gestion des ressources en eau du Sud Tunisien. PhD thesis, University of Paris South, Paris
Meyer FW (1989) Groundwater movement in the Floridan Aquifer System in southern Florida: groundwater movement based on natural isotopes as tracers. In: US geological survey professional paper 1403-G: hydrogeology, groundwater movement and subsurface storage in the Floridan Aquifer system in southern Florida. US Geological Survey, USA
Osmond KJ, Cowart JB (1976) The theory and uses of natural uranium isotope variations in hydrogeology. Atomic Energy Rev 144:621–679
Osmond JK, Cowart JB (1992) Groundwater. In: Ivanovich M, Harmon R (eds) Uranium series disequilibrium: applications to environmental problems, Oxford University Press, Oxford, pp 290–323
Osmond JK, Cowart JB (2000) U-series nuclides as tracers in groundwater hydrology. In: Cook PG, Herczeg AL (eds) Environmental tracers in subsurface hydrology. Kluwer, Boston, pp 145–174
Oss (2003) Système aquifère du Sahara Septentrional Une conscience de bassin. Volume II: Hydrogéologie. Observatoire du Shara et du Sahel, pp 322
Roback RC, Johnson TM, McLing TL, Murrell MT, Luo S, Ku TL (2001) Uranium isotopic evidence for groundwater chemical evolution and flow patterns in the eastern Snake River Plain aquifer Idaho. Geological Society of America Bulletin 113(9):1133–1141
Suski J, Rasilien K, Casanova J, Ruskeeniemi T, Blomqvist R, Smellie JA (2001) U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes. J Contam Hydrol 47:187–196
Thurber DL (1962) Anomalous 234U/238U in nature. J Geophys Res 65:4518–4523
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Chkir, N., Zouari, K. Uranium isotopic disequilibrium for groundwater classification: first results on complexe terminal and continental intercalaire aquifers in Southern Tunisia. Environ Geol 53, 677–685 (2007). https://doi.org/10.1007/s00254-007-0682-1
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DOI: https://doi.org/10.1007/s00254-007-0682-1