Sediment surface geochemistry of three Baltic Sea deep basins

Three deep basins were chosen for this study and the most recent changes th at are reflected in the uppermost 15 to 35 cm are reported. The Gotland Bas in, the largest continuous sedimentation basin in the southern Baltic Sea, was chosen for the present study. Simultaneously, a quite large basin, the North Central Baltic Basin was investigated and chemical data are reported for the first time. In the southern Baltic Sea the Bornholm Basin was inves tigated. All 3 basins are different as regards the physicochemical conditio ns in the area. The investigated elements were divided into different group s according to their origin and geochemical behavior: elements of natural t errestrial origin; nutrients; elements that are confined to early diageneti c minerals; and in the near-surface zone the anthropogenic elements includi ng several harmful metals. Although there seems to be a decreasing trend in the surface zone the metal concentrations are still clearly elevated.