Uranium series isotopes in the Avon Valley, Nova Scotia

J. Kronfeld, D. I. Godfrey-Smith, D. Johannessen, M. Zentilli

Research output: Contribution to journalArticlepeer-review

Abstract

An U-series isotopic study was carried out in the waters of the Avon Valley, Nova Scotia. The fresh and acidic recharge waters flow rapidly through the watershed composed of a granitic highland and a sedimentary, largely carbonate, lowland plain, before draining to the sea. There is no significant anthropogenic pollution; but, naturally elevated U levels can be encountered within the bedrock. Nonetheless, the U concentrations of the surface and groundwater are low (generally within the range of several hundredths to several tenths of a μg l-1), except in the proximity to weathering of U mineralization. The dissolved U in the surface waters appears to be stabilized by organic rather than inorganic complexes. Both the groundwaters and surface waters have similar 234U/238U activity ratios that rarely deviate from secular equilibrium by more than 20% throughout the watershed. The magnitude of the 234U/238U activity ratio is not determined by lithology but rather by the weathering mechanism, the high rate of flushing, and the leaching of local U mineralization. Dissolved Ra is consistently absent. The dissolved Rn concentrations, though variable, are measurable even in surface waters. This may be due to a continual degassing from the U-enriched bedrock or release from local sites of U mineralization underlying the surface water sources.

Original languageEnglish
Pages (from-to)335-352
Number of pages18
JournalJournal of Environmental Radioactivity
Volume73
Issue number3
DOIs
StatePublished - 2004

Keywords

  • Alpha recoil
  • Groundwater
  • Leaching
  • Nova Scotia
  • Ra
  • Rn
  • U mineralization
  • U series disequilibrium

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