Selected coring areas along the coast of Sweden

The conditions for erosion, transportation and deposition of sediment continue to change in several of the studied coastal areas mainly due to land uplift and the effect of human activities. In the deeper parts of many bays and basins, formerly oxygeneted bottom waters and sediments have turned anoxic, partly as a result of eutrophication. Since this ongoing process results in progressive environmental changes, a monitoring strategy is required by which such changes can be documented. In several of the coastal areas, named on the map below and in the frame to the left, the method of radiographic core-to-core correlation has been used for monitoring sedimentation.

Locations of the coastal areas with the selected coring stations.

In several of the studied areas the border was sharp between the lower bioturbated and the upper, often gas-rich and annually laminated sediments, though a variation betweeen bioturbated and laminated sediment parts also was found in several of the X-rayed sediment cores. The formation of cyclic and event types of stratification were observed by comparing stereoradiographs of sediment cores collected from selected locations during different seasons, and sometimes also before and after a specific event such as a major storm, algal bloom, or dredging operation. Special attention was given to those bays and basin parts, where annually laminated, modern deposits and datable turbidites, storm deposits, or layers of redeposited dredge material occur, because these can be used to test models for the deposition and reworking of sediment.

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