Main regularities of the Late Pleistocene-Holocene transgression of the Black Sea

A mathematical model describing the Black Sea level change in the Late Pleistocene-Holocene is offered. A theoretical curve for temporal change in the sea level is obtained. It is established that, in the range from 20 to 12 ky BP, the sea level rose to ∼20 m and fluctuated with various amplitudes and periods. In the range from 12 to 11 ky BP during the Bosphorus Strait formation, there was a sea regression by 30–50 meters, and level of the Black Sea dropped to the World Ocean level. Further, it mirrored variation of the ocean level.     

The response of benthic foraminifera and ostracoda to heavy metal pollution in Gulf of Izmir (Eastern Aegean Sea)

Benthic foraminifera can be used as environmental bioindicators, especially in polluted environments where their sensitivity to pollutants may be expressed by a modification in the assemblage. Nineteen sediment samples were collected in November 2002 from surficial sediments of the Gulf of Izmir (Turkey). The Gulf of Izmir is located in Western Turkey and surrounded by a densely populated community. The gulf has been contaminated by numerous heavy metals, but geochemical analyses have shown that metals are significant pollutants only in the inner part of the gulf. Outer and Middle Sections showed low levels of heavy metals, except the estuary of Gediz River. Eight heavy metals have been analyzed in all the sampling points. Sixty-seven foraminifer and 22 ostracod species were identified in 16 sediment samples. Statistical analysis shows that there is a significant correlation between foraminifera species and heavy metals. The most polluted Inner Sections are dominated by the tolerant species Ammonia tepida that may be used as pollution indicator. The gradient observed in heavy metal concentrations between the Outer and Inner Sections has a prevalent influence on the foraminiferal distribution. There is a gradient of the number of species, increasing from the Inner Section toward the Outer Section. The occurrence of test abnormalities among foraminifera may represent a useful biomarker for evaluating long-term environmental impacts in a coastal region.     

Behavior of homogenous rubble mound breakwaters materials under cyclic loads

Rubble-mound breakwaters are subjected not only to water wave action but also to other types of environmental loading, such as earthquakes. The design of coastal structures should take into account the most relevant factors in each case, including seismic loading. The purpose of this study is to understand the dynamic response of breakwater materials in dry and water conditions. Hence, an experimental study was carried out for homogeneous breakwater structures subjected to different dynamic loadings with variable frequencies and amplitudes in a shaking tank. A shaking tank with a single degree of freedom was developed. The experiments were performed with rigid bottom conditions. The model scale was 1/50. The cyclic responses of the breakwater made of entirely armor material and another of entirely core material were examined separately, and their behaviors were then compared. The experimental results are also discussed with a numerical study, and the material properties and failure modes were thus defined. It is found that the settlement of the armor and core materials under cyclic loads increased with increasing base acceleration level. The cyclic deformation of the rubble mound breakwater in water was larger than that under dry conditions. The cyclic deformation of the rubble materials resulted in crest lowering and slumping. Dominant mode of the seismic failure was associated with the settlement of the crown of the structure accompanied by densification of the core material.