Geochemical expressions of late- and post-glacial land–sea interactions in the southern Baltic Sea

The coastal region of the southern Baltic Sea has been extremely sensitive to sea-level changes during the Quaternary. The present environment is comprised of coastal lagoons and is characterized by Pleistocene islands connected by Holocene barrier islands. To determine the effects of late- and post-glacial coastal development on the lagoon sediments, 13 sediment cores from 6 lagoons were investigated. Organic carbon to nitrogen (Corg/N), and organic carbon to sulfur ratios (Corg/S), [delta]13C, [delta]15N, organic carbon, biogenic opal and calcium carbonate values were measured and linked to the late- and post-glacial biostratigraphy of the sediments. Although, with the exception of the Oder lagoon, the lagoons show similarities in their paleoenvironments derived from the Corg/S ratios in the sediment, it is possible to derive the influence of the Baltic Sea waters. Corg/N ratios, [delta]13C, [delta]15N, organic carbon, biogenic opal and calcium carbonate values all reflect changes in productivity over time and influence of river input, transgression and erosion. The results were used to derive the effects of sea-level changes, coastal development and related changes in hydrography and accompanying accumulation processes at the bottom of the lagoons. The results of this study show that, depending on its position to the Baltic Sea, each lagoon responded differently to sea-level changes that occurred during the development of the Baltic Sea and to regional coastal development.