Stable oxygen and carbon isotopes of planktic and benthic foraminifera from the Lardos SW hill section, Rhodes, Greece

Stable oxygen and carbon isotopes were measured on (i) the planktic foraminifera species Globigerinoides ruber (white) and alternatively, in samples in which G. ruber was lacking, on Globigerinoides conglobatus; and (ii) the benthic foraminifera species Cibicidoides pachyderma and alternatively, in samples in which C. pachyderma was lacking, on Cibicides lobatulus. 10–15 planktic and 4-6 benthic specimens of the fraction >250 μm were selected. Additionally, attention was paid to select specimens of similar size to minimise influences of metabolic effects and changing preferential habitats during ontogeny. For cleaning and removal of sediment, the selected foraminifera were cracked between two glass plates, transferred to a sample cup, covered with ethanol and immerged into an ultrasonic bath for 5–10 s. The sediment brought into suspension was decanted. The procedure was repeated until the ethanol remained clear after the ultrasonic bath. The cleaned foraminifera were reacted with 100% phosphoric acidat 75 °C using a Kiel III online carbonate preparation line connected to a ThermoFinnigan 252 mass spectrometer (Geochemical Laboratory of the GeoZentrum Nordbayern,Germany). Isotopic data are expressed in per mil relative to V-PDB by assigning a δ18O-value of -2.20 ‰ to NBS19, using the standard δ-notation. The reproducibility was checked by replicate analysis of laboratory standards and was found to be better than ±0.05 for δ18O and δ13C (1σ).