The 137Cs activity of the first set of samples consisting of the 55
replicate cores collected during the sampling campaign undertaken
in 1998 was measured using a high resolution HPGe detector in the
Laboratory of the Department of Nuclear Engineering at the University
of Palermo, Italy. Count times were ca. 30,000 s, providing a
precision of ca. ±10% at the 95% level of confidence. The second set
of samples collected from the catchment in 1999, which included
both the depth incremental samples provided by the scraper plate
and the sectioned cores collected from the reference area, was
analysed using a high resolution HPGe detector in the Laboratory of
the Department of Geography at the University of Exeter, UK. Count
times were again ca. 30,000 s, providing a precision of ca. ±10% at
the 95% level of confidence. The third set of samples, collected in
2013, during the repeat-sampling campaign, was analysed using
high resolution HPGe detectors in the Department of Physics at the
University of Basel and the State Laboratory Basel-City, Switzerland.
Because of the expected lower activity of these samples, counting
times were increased to ca. 80,000 s providing a precision of ca.
±10% at the 95% level of confidence. The total inventory or areal
activity density (Bq m2) of each bulk core was calculated as the
product of the measured 137Cs activity (Bq kg1) and the dry mass
of the