Analysis of Mn-nodules from Breitgrund, Baltic Sea

The usually high concentrations of Zn, Pb, Cd, and Cu in the most recently accreted portions of ferromanganese nodules from the western Baltic Sea are thought to reflect increased metal input due to anthropogenic mobilization. If so, the point of increase represents a time horizon within the structure of the nodule. Similar trace metal distributions of radiometrically dated sediments from the same area suggest that the ferromanganese nodules have grown in thickness between 0.02 and 0.16 mm yr-1. From this growth rate anthropogenic Zn flux to the nodule surface was calculated to be 80 mg m-2 yr-1.

Concentrations of phosphates and silicon in near-bottom and interstitial waters of the Baltic Sea

Fine structure of vertical distributions of phosphorus and silicon in near-bottom layers and interstitial waters is studied in different regions of the Baltic Sea (Gulf of Finland, Bornholm area, Gotland trench). Data obtained are used to calculate fluxes of mineral forms of phosphorus and silicon in exchange processes between sediments and the near-bottom water layer. Depending on sediment types, values of nutrient fluxes vary from 9.8 to 632.6 µg-at/m**2/day for phosphorus and from 232.4 to 1881.1 µg-at/m**2/day for silicon. Fluxes calculated for different regions are compared.