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Author Rajfur, M.; Kłos, A.; Wacławek, M. url  openurl
  Title Sorption properties of algae Spirogyra sp. and their use for determination of heavy metal ions concentrations in surface water Type Journal Article
  Year 2010 Publication Bioelectrochemistry Abbreviated Journal  
  Volume 80 Issue 1 Pages 81-86  
  Keywords Biomonitoring, Heavy metal ions, Algae sp., Sorption kinetics, Langmuir isotherm  
  Abstract Kinetics of heavy-metal ions sorption by alga Spirogyra sp. was evaluated experimentally in the laboratory, using both the static and the dynamic approach. The metal ions – Mn2+, Cu2+, Zn2+ and Cd2+ – were sorbed from aqueous solutions of their salts. The static experiments showed that the sorption equilibria were attained in 30min, with 90-95% of metal ions sorbed in first 10min of each process. The sorption equilibria were approximated with the Langmuir isotherm model. The algae sorbed each heavy metal ions proportionally to the amount of this metal ions in solution. The experiments confirmed that after 30min of exposition to contaminated water, the concentration of heavy metal ions in the algae, which initially contained small amounts of these metal ions, increased proportionally to the concentration of metal ions in solution. The presented results can be used for elaboration of a method for classification of surface waters that complies with the legal regulations.  
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  ISSN 1567-5394 ISBN Medium  
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  Notes A Selection of Papers presented at the 4th International Workshop on Surface Modification for Chemical and Biochemical Sensing (SMCBS 2009) Approved no  
  Call Number THL @ christoph.kuells @ Rajfur201081 Serial (down) 283  
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Author Heaton, T.H.E.; Talma, A.S.; Vogel, J.C. url  openurl
  Title Origin and history of nitrate in confined groundwater in the western Kalahari Type Journal Article
  Year 1983 Publication Journal of Hydrology Abbreviated Journal  
  Volume 62 Issue 1 Pages 243-262  
  Keywords  
  Abstract Data are presented for nitrate, dinitrogen and argon concentrations and 15N14N ratios in groundwater, with radiocarbon ages up to 40,000 yr. for three confined sandstone aquifers in the western Kalahari of South West Africa/Namibia. The nitrate is probably generated within the soil of the recharge areas, and its production rate during the period 3000-40,000 B.P. has remained between 0.5 and 1.6 meq NO−3l−1 of recharge water, with ° 15N between + 4 and + 8‰. Variations in the amount of nitrate and of “excess air” in groundwater recharge are found, and can only reflect changes in the environmental conditions during recharge. They must therefore be caused by the climatic changes that have taken place during the past 25,000 yr.  
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  ISSN 0022-1694 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Heaton1983243 Serial (down) 282  
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Author Wilson, G.B.; McNeill, G.W. url  openurl
  Title Noble gas recharge temperatures and the excess air component Type Journal Article
  Year 1997 Publication Applied Geochemistry Abbreviated Journal  
  Volume 12 Issue 6 Pages 747-762  
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  Abstract The calculation of a groundwater recharge temperature based on the dissolved concentrations of Ne, Ar, Kr and Xe requires a correction for noble gas supersaturation due to excess air entrainment. This entrainment is commonly attributed to the recharge process or to air contamination at the wellhead during sample collection. With the exception of some local studies, most work has concentrated on interpretation of the recharge temperature or quantification of the radiogenic content for palaeoclimatic and dating purposes. The magnitude and source of the excess air is not directly relevant to these studies and so is often ignored. In this work, excess air Ne and other data have been calculated from new and published noble gas data sets for several groundwater systems. For younger groundwaters which have been recharged under one broad climatic regime, the amount of air entrainment increases according to lithology in the order granites, sandstones and limestones respectively. A negative correlation between precipitation and excess air entrainment is identified in at least one aquifer, and some of the mechanisms which may influence the entrainment process are discussed.  
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  ISSN 0883-2927 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Wilson1997747 Serial (down) 281  
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Author Vogel, J.C.; Talma, A.S.; Heaton, T.H.E. url  openurl
  Title Gaseous nitrogen as evidence for denitrification in groundwater Type Journal Article
  Year 1981 Publication Journal of Hydrology Abbreviated Journal  
  Volume 50 Issue Pages 191-200  
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  Abstract By investigating the nitrate, oxygen, nitrogen and argon concentrations and 15N14N ratios in artesian groundwater with radiocarbon ages ranging up to 27,000 yr. a process of very slow denitrification in a confined aquifer is demonstrated. The calculated nitrogenisotope fractionation factor associated with this reaction is comparable to that reported for bacterial cultures in vitro and in vivo.  
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  ISSN 0022-1694 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Vogel1981191 Serial (down) 280  
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Author Stone, A.E.C.; Edmunds, W.M. url  openurl
  Title Naturally-high nitrate in unsaturated zone sand dunes above the Stampriet Basin, Namibia Type Journal Article
  Year 2014 Publication Journal of Arid Environments Abbreviated Journal  
  Volume 105 Issue Pages 41-51  
  Keywords Kalahari, Namibia, Nitrate in the unsaturated zone, Stampriet Basin, Transboundary basin, Unsaturated zone recharge  
  Abstract Elevated groundwater nitrate levels are common in drylands, often in excess of WHO guidelines, with concern for human and animal health. In light of recent attempts to identify nitrate sources in the Kalahari this paper presents the first unsaturated zone (USZ) nitrate profiles and recharge rate estimates for the important transboundary Stampriet Basin, alongside the first rainfall chemistry records. Elevated subsurface nitrate reaches 100–250 and 250–525 mg/L NO3–N, with NO3–N/Cl of 4–12, indicating input above evapotranspiration. Chloride mass balance recharge rates range from 4 to 27 mm/y, indicating a vertical movement of these nitrate pulses toward the water table over multi-decadal timescales. These profiles are sampled from dune crests, away from high concentrations of animals and without termite mounds. Given low-density animal grazing is unlikely to contribute consistent spot-scale nitrate over decades, these profiles give an initial estimate of naturally-produced concentrations. This insight is important for the management of the Stampriet Basin and wider Kalahari groundwater. This study expands our knowledge about elevated nitrate in dryland USZs, demonstrating that it can occur as pulses, probably in response to transient vegetation cover and that it is not limited to long-residence time USZs with very limited downward moisture flux (recharge).  
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  ISSN 0140-1963 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Stone201441 Serial (down) 279  
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