Offsets of isotopic values (>63 µm minus 10-20 µm fraction), offsets in non-biogenic silica contamination (estimated from particle counts and content of Al2O3 determined by ICP-OES or EDS, where in bold italics) and differences in the relative abundance of spring/summer species (10-20 µm minus >63µm fraction), which equals the relative abundance of Thalassiosira spp. and Actinocyclus spp. in the 10-20 µm fraction.# = Value excluded from mean offset calculation considering the relatively high standard deviations (see Table 4.2).