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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Measurement of 135Cs/137Cs in environmental samples

Currently Active: 

Radioactive caesium isotopes 135Cs and 137Cs can be present in environmental samples, originating from nuclear power plants and reprocessing sites, nuclear accidents and fallout from atmospheric weapons testing.  135Cs/137Cs varies with reactor, weapon and fuel types, and can therefore be used as an indicator of radioactive contamination. 

Atmospheric nuclear weapons test  fallout and discharges from the Sellafield reprocessing site are potential sources of  135Cs and 137Cs (Source:
Nuclear fallout


A method is being developed that will enable the precise measurement of 135Cs/137Cs, incorporating sample digestion, chemical separation, and high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) quantification.

135Cs and 137Cs analysis is affected by interferences from naturally occurring barium (135Ba and 137Ba), and complete chemical separation of Cs is required to recover accurate isotopic composition.

Chemically separated samples will measured using the ELEMENT single collector and NEPTUNE multi-collector HR-ICP mass spectrometers.



Sellafield reprocessing site

Research Aims

  1. Develop a robust method for precise measurement of 135Cs/137Cs.
  2. Apply this method to a range of environmental samples including salt marsh sediments and North Atlantic/Arctic Ocean waters.
  3. Build on previous work investigating plutonium isotope ratio variations measured in herbage and ice core archives.
Summary of the two-stage chemical separation procedure for caesium (Source: B Russell)
Chemical separation procedure

Key Contacts

Ben Russell (Postgraduate Research Student)

Prof. Ian Croudace (Supervisor, Principal Investigator)

Dr. Phil Warwick (Supervisor, Principal Investigator)

Dr. Rex Taylor (Supervisor)

Dr. Martin Dutton (NNL Industry Supervisor)



Seawater collection in the Arctic Ocean, which has been contaminated by multiple nuclear sources. (Source: B.Russell)
Seawater contamination

Related Links

Warneke T. et al. (2002) A new ground-level fallout record of uranium and plutonium isotopes for northern temperate latitudes.




PhDs and Other Opportunities


Associated research themes

Environmental Geochemistry and Radioactivicty

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