Application of 234U/238U activity ratios to investigations of subterranean groundwater discharge in the Cádiz coastal area (SW Spain)

J. F. Rodrigo, M. Casas- Ruiz, J. Vidal, L. Barbero, M. Baskaran, M. E. Ketterer

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The activity ratios of 234U/238U were used to investigate processes of subterranean groundwater discharge into coastal marine waters in a study location at Bay of Cádiz (southwest Spain). Marine waters in the bay and surrounding open ocean exhibited U concentrations of 3.4±0.1μg/L and activity ratios of 1.15±0.01, in agreement with the expected composition of seawater (234U/238U activity ratio=1.148±0.002). Three water samples obtained from the discharge zone of the Guadalete River exhibited activity ratios of 1.17-1.22 along with slightly lower U concentrations compared to seawater, which is likely due to mixing between seawater and a groundwater end-member. One possible source of groundwater was characterized by sampling and analyzing a well water sample collected in the neighboring village of El Puerto de Santa María; this water sample exhibited an activity ratio of 1.34±0.03 and a U concentration of 1.22μg/L. Water from the Guadelete River estuarine zone can be explained to result from a two-component mixture of seawater and groundwater from the El Puerto de Santa María well; however, if there are several groundwater reservoirs with different U activity ratios that discharge to the coastal water, then, it may be difficult and more studies are being conducted to address this issue.

Original languageEnglish (US)
Pages (from-to)68-71
Number of pages4
JournalJournal of Environmental Radioactivity
StatePublished - Apr 2014


  • Coastal aquifers
  • ICP-MS
  • Submarine groundwater discharge (SGD)
  • U/U activity ratios

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis


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