Table 4.5.6. Thule-1997. Plutonium Concentration Ratios, CR, Bq ^239,240Pu kg^-1 dry biota / Bq kg^-1 dry sediment between various groups of benthic biota and upper 3 cm of sediments. Class Species CR, Bq kg^-1 biota /   Bq kg^-1sediment (0-3 cm) Average SD n Mollusc Bivalves 0.025 0.024 13 Mollusc Macoma calcarea    37^* 1 Mollusc Snails 0.0033 0.0018 9 Mollusc Squid, Rossia sp.     0.00036 1 Echinoderm Starfish 0.0094 0.0139 9 Echinoderm Brittle stars 0.013 0.0159 4 Echinoderm Feather stars 0.0070 0.0060 4 Echinoderm Sea Urchins 0.12 0.16 4 Echinoderm Sea cucumber 0.0080 0.0083 4 Crustacea Shrimp 0.0048 0.0088 4 Crustacea var. 0.038 0.039 4 Annelida Pectinaria 0.068 0.05234 4 Annelida var. 0.023 0.033 10 Annelida Tube 0.28 0.29 6 Fish Liparis sp. 0.00035 1 ^*: Outlier, probably caused by hot particle