In all three basins, activity concentrations of both 210Pbtot and 210Pbsupp decline exponentially with the sediment depth, thus providing a basis for the application of both dating

models CF:CS and CRS (Boer et al., 2006, Carvalho Gomes et al., 2009 and Díaz-Asencio et al., 2009). Similar distribution was observed in Gdańsk Deep by Pempkowiak (1991). 214Bi activities along the core profiles changed in relatively narrow ranges. The maximal differences in a given basin were up to 10 Bq kg−1, with the mean at the level of 39 ± 3 Bq kg−1 in the Bornholm Deep, 35 ± 3 Bq kg−1 in the SE Gotland Basin and 45 ± 7 Bq kg−1 in the Gdańsk Deep. The maximal activity concentrations of 210Pbex were found in the surface sediment layer in the Gdańsk Deep (420 Bq kg−1) and decreased rapidly to 5 Bq kg−1 at 21 cm PLX3397 depth of the sediment. In the SE Gotland Basin activity concentrations varied from 4 Bq kg−1 in the deepest sediment layers to 242 Bq kg−1 in the surface layer, while the youngest sediments of the Bornholm Deep showed the least activity Thiazovivin order of 210Pbex (151 Bq kg−1). The age of individual sediment

layers was determined using the CRS model applying the cumulative depth instead of the real depth to eliminate the sediment compaction effect and related variable content of interstitial water (Fig. 2). The obtained statistically significant correlations between the age of sediment layer and cumulative depth were described with 2nd degree polynomial function in all three studied sedimentation basins. The correlation coefficients reached 0.980,

0.999 ZD1839 cell line and 0.997 in the SE Gotland Basin, Bornholm Deep and the Gdańsk Deep, respectively, at confidence limit of p = 0.0000 ( Fig. 2). The ages of sediment layers, and time of their formation, are quite close in the SE Gotland Basin and in the Gdańsk Deep – the deepest layers of formation in these basins were estimated at 1838 and 1858, respectively. The sediment layer at 21 cm depth in the Bornholm Basin comes from a decidedly later period – 1928, indicating a greater sedimentation rate. These observations were certified by the linear accumulation rate obtained from the CF:CS model. The linear accumulation rate determined in the Gdańsk Deep reached 0.18 cm yr−1 confirming earlier investigations ( Pempkowiak, 1991) and was relatively close to that in the Gotland Basin (0.14 cm yr−1). The corresponding mass accumulation rates in these basins were 0.032 g cm−2 yr−1 and 0.049 g cm−2 yr−1. In the Bornholm Deep the identified linear accumulation rate and the mass accumulation rate were much higher, 0.31 cm yr−1 and 0.059 g cm−2 yr−1, respectively. Fresh water discharge from rivers and the extent of riverine water in the sea are the factors directly influencing the amount of suspended matter in the water column and consequently affect the intensity of the sedimentation process.