137Caesium activity content data of seabed surface sediments from the Gulf of Bothnia, northern Baltic Sea

This dataset includes contents of 137Caesium in surface sediments determined for 1-cm sediment slices of 54 short gravity-cores from the Gulf of Bothnia, northern Baltic Sea. The 137Cs activity of untreated samples was measured by gamma spectrometry using an EG&E Ortec ACE™-2K spectrometer with a four-inch NaI/TI detector at the Geological Survey of Finland (GTK), Espoo. Since 2017, the 137Cs activity of sediment samples has been measured for 60 min using a BrightSpec bMCA-USB pulse height analyser coupled to a well-type NaI(Tl) detector at the Geological Survey of Finland. The 137Cs activity contents are presented per wet weight (Bq kg-1). Samples collected and measured over different years from 2001 to 2019 gave 137Cs values representing discrete time frames during the 18-year sampling/measuring interval, and are not fully, directly comparable. Thus, dataset lists also 137Cs activity content values decay corrected to 2021.