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Abstract: The sediments of a deep sea core (Z1) taken from the north-eastern part of the Ionian Sea near Corfu Island (Greece) was studied in order to reconstruct the palaeoenvironmental history of the basin over the time interval between 22 and 1.5 ka. The downcore variation in the associations of planktonic foraminifera provides a continuous record of the faunal changes over this period. A succession of eight (8) main biozones, based on the major changes in the planktonic foraminifera record, were recognized. Their comparisons with records from the Tyrrhenian and the Adriatic Seas have shown that there is a similarity and synchroneity in the zonation. Furthermore, the downcore compositional changes of the planktonic foraminiferal assemblages and the δ 18Ο signal made possible allowed the recognition of millennial to centennial climatic instabilities. These climatic instabilities are associated with the Heinrich 1 (H1) event, the GI-1a to GI-1e INTIMATE events, the Younger Dryas and the Holocene cool events at 8.2 ka, 7 ka, 5 ka, 4 ka and 3 ka. R-mode factor analysis applied to the percentage abundance of plantkonic foraminifera species from seven cores in the Ionian, Adriatic and Tyrrhenian Seas showed that the faunal composition in the three seas was controlled by temporal and spatial variations in: (i) the sea surface temperature, (ii) the stratification and mixing of the surficial waters and (iii) the fertility of surface waters associated with upwelling and/or river inputs. These variations were in phase or out of phase in the three seas. [Copyright &y& Elsevier]

Abstract: The distribution of the natural radionuclides (238U, 232Th, 226Ra, 40K) and the artificial 137Cs was studied in sediment cores collected from Amvrakikos Gulf, a seasonal anoxic marine basin, using γ-ray spectrometry. The activity of radionuclides, along with the concentrations of Fe and Mn, were also studied in relation to the total organic carbon and the granulometric fractions of the sediments. The results obtained revealed higher 238U activity concentrations in all the examined sediment samples compared to the world and Greek average values for soil. The high activity values of 238U are attributed, besides the lattice-held fraction, to phosphate fertilizer inputs in the Gulf via major rivers and/or to alteration processes of phosphate ores located mainly in the drainage basin of the river Louros. The elevated activity values of 40K could be attributed to the mineralogical composition of the sediments and to phosphate fertilizers containing potassium. Organic matter seems to be a more efficient sorbent for U than clay minerals and amorphous Fe and Mn-oxyhydroxides. Scanning electron microscopy, together with qualitative analysis of some smectites, reveals the occurrence of U, suggesting a limited absorption of U onto clay minerals. The applied BCR sequential extraction procedure revealed that U was found mainly in the refractory phase or associated with organic matter and to a lesser extent as surface-coating oxides, with the exception of one sediment core which is characterized by high content of fresh marine organic matter and presents high percentage of U in the exchangeable fraction. [Copyright &y& Elsevier]