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Author Brook, G.A.; Railsback, L.B.; Marais, E. url  openurl
  Title Reassessment of carbonate ages by dating both carbonate and organic material from an Etosha Pan (Namibia) stromatolite: Evidence of humid phases during the last 20ka Type Journal Article
  Year 2011 Publication Quaternary International Abbreviated Journal  
  Volume 229 Issue 1 Pages (up) 24-37  
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  Abstract Previous research on lacustrine stromatolites from Etosha Pan in Namibia obtained ages on carbonate close to or beyond the limits of radiocarbon dating. These ages suggested that the basin was likely not subject to extensive flooding during the last ca. 40ka. This study shows that AMS radiocarbon ages for the carbonate of a stromatolite from Poacher’s Point are 15–21ka older than ages for organic material in the stromatolite structure. Calibrated ages range from 30 to 40ka for carbonate and 3–19ka for the organic residue. The new ages, together with petrographic and isotopic data for the stromatolite, have provided important new information on past flooding of Etosha Pan including evidence of prolonged lacustrine conditions during the Holocene Climatic Optimum.  
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  ISSN 1040-6182 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ brook_reassessment_2011 Serial 110  
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Author Silva, M.L. da; Bonotto, D.M. url  openurl
  Title Uranium isotopes in groundwater occurring at Amazonas State, Brazil Type Journal Article
  Year 2015 Publication Applied Radiation and Isotopes Abbreviated Journal  
  Volume 97 Issue Pages (up) 24-33  
  Keywords Amazon area, Dissolved uranium, Groundwater, Tube wells, U/U activity ratio  
  Abstract This paper reports the behavior of the dissolved U-isotopes 238U and 234U in groundwater providing from 15 cities in Amazonas State, Brazil. The isotope dilution technique accompanied by alpha spectrometry were utilized for acquiring the U content and 234U/238U activity ratio (AR) data, 0.01–1.4µgL−1 and 1.0–3.5, respectively. These results suggest that the water is circulating in a reducing environment and leaching strata containing minerals with low uranium concentration. A tendency to increasing ARs values following the groundwater flow direction is identified in Manaus city. The AR also increases according to the SW–NE directions: Uarini→Tefé; Manacapuru→Manaus; Presidente Figueiredo→São Sebastião do Uatumã; and Boa Vista do Ramos→Parintins. Such trends are possibly related to several factors, among them the increasing acid character of the waters. The waters analyzed are used for human consumption and the highest dissolved U content is much lower than the maximum established by the World Health Organization. Therefore, in view of this radiological parameter they can be used for drinking purposes.  
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  ISSN 0969-8043 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ silva_uranium_2015 Serial 140  
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Author Klock, H.; Külls, C.; Udluft, P. openurl 
  Title Quantification of Groundwater Recharge-Estimating recharge values using hydrochemical and geological data: A case study from the semiarid Kalahari catchment of northern Namibia Type Journal Article
  Year 2001 Publication IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences Abbreviated Journal  
  Volume 269 Issue Pages (up) 25-32  
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  Publisher Wallingford [Oxfordshire]: IAHS, 1981- Place of Publication Editor  
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  Call Number THL @ christoph.kuells @ Klock2001 Serial 32  
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Author Klock, H.; Külls, C.; Udluft, P. openurl 
  Title Estimating recharge values using hydrochemical and geological data: a case study from the Type Conference Article
  Year 2001 Publication Impact of Human Activity on Groundwater Dynamics: Proceedings of an International Symposium (Symposium S3) Held During the Sixth Scientific Assembly of the International Association of Hydrological Sciences (IAHS) at Maastricht, The Netherlands, from 18 t Abbreviated Journal  
  Volume Issue 269 Pages (up) 25  
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  Area Expedition Conference International Assn of Hydrological Sciences  
  Notes Approved no  
  Call Number THL @ christoph.kuells @ Klock2001estimating Serial 60  
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Author Edmunds, W.M.; Shand, P.; Hart, P.; Ward, R.S. url  openurl
  Title The natural (baseline) quality of groundwater: a UK pilot study Type Journal Article
  Year 2003 Publication Science of The Total Environment Abbreviated Journal  
  Volume 310 Issue 1 Pages (up) 25-35  
  Keywords Baseline quality, Groundwater, Hydrogeochemistry, Monitoring, Water Policy  
  Abstract Knowledge of the natural baseline quality of groundwaters is an essential prerequisite for understanding pollution and for imposing regulatory limits. The natural baseline of groundwaters may show a range of concentrations depending on aquifer mineralogy, facies changes, flow paths and residence time. The geochemical controls on natural concentrations are discussed and an approach to defining baseline concentrations using geochemical and statistical tools is proposed. The approach is illustrated using a flowline from the Chalk aquifer in Berkshire, UK where aerobic and anaerobic sections of the aquifer are separately considered. The baseline concentrations for some elements are close to atmospheric values whereas others evolve through time-dependent water–rock interaction. Certain solutes (K, NH4+), often considered contaminants, reach naturally high concentrations due to geochemical controls; transition metal concentrations are generally low, although their concentrations may be modified by redox controls. It is recommended that the baseline approach be incorporated into future management strategies, notably monitoring.  
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  ISSN 0048-9697 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ edmunds_natural_2003 Serial 166  
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