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Abstract: The analysis of the lithofacies preserved in recent marine sediments in Cadiz Bay, shows major fluctuations in the depositional regime, which are characterized by significant energy variations. Drilling and geophysical data indicate the presence of coarse materials such as gravel, imbricated shells and plant remains, and frequent flow structures which have been interpreted as a result of the action of high energy events, while the finest sediments present in the cores are interpreted as a consequence of the ordinary depositional regime, fundamentally controlled by normal storm surge and tidal currents. Three types of sequence are differentiated: Very High Energy (VHE) sequences, High Energy (HE) sequences and Low Energy (LE) sequences. The VHE and HE sequences were caused by highly energetic oceanic agents such as great waves generated by major storms or tsunamis. There is no historical evidence of the action of sufficiently energetic storms, while the geological setting of Cadiz Bay is located near the Azores–Gibraltar fault, the limit between the African and European plates, points to tsunami action as being the most plausible option to explain the origin of these deposits. The radiocarbon age indicates that these high energy events happened between 898±120 BC and 849±121 AD, some of which coincide with several historically documented tsunamis affecting the Cadiz coast. This data indicates that the period from 849 AD to 1200 AD was a time of intense seismic and tsunamigenic activity. [Copyright &y& Elsevier]

Sediments are an essential component of aquatic ecosystems that must be assessed and managed properly. The use of quantitative environmental quality standards derived from consideration of sediment quality guidelines (SQGs) can be effective as part of a tiered risk assessment approach. In Part I of this 2-part paper addressing sediment quality assessment and dredged material management in Spain, different SQG methods are used to evaluate sediment quality in the Bay of Santander, located in the Cantabric Sea along the northern coast of Spain, and to guide development of empirically derived SQGs for marine sediments. The results of the study indicate a great heterogeneity of SQGs, both with regard to the numeric values for a particular chemical and the number of substances for which SQGs have been derived. The analysis highlights the scarce development of empirical SQGs for priority substances identified in current European Union water policy. Nonetheless, the application of SQGs makes it possible to classify different zones of sediment quality in the Bay of Santander. Part II of this 2-part paper considers the environmental impacts of dredged material disposal. Legislation and criteria used to regulate dredged material disposal at sea in different European countries are reviewed, and action levels derived by different countries were used to evaluate management of dredged sediments from Cádiz Bay, located on the South Atlantic coast of Spain. [ABSTRACT FROM AUTHOR]