Browsing by Author "Pascual, Marina Astudillo"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- Phosphorus dynamics in Gulf of Finland sediments with contrasting redox conditionsPublication . Pascual, Marina Astudillo; Slompa, Caroline P.; Veiga-Pires, C.Enhanced phosphorus (P) and nitrogen (N) inputs have resulted in eutrophication and subsequent depletion of oxygen (O2) in the bottom water (BW) of the Gulf of Finland (GoF). The P cycling is controlled by the redox state of the system. For a complete understanding of the P dynamics in the GoF, we conducted detailed chemical analyses in order to assess the mechanisms responsible for P burial and release under different redox conditions. Here, we present porewater and sediment data for four different sites in the GoF. We used a combination of three sequential extraction methods (for P, iron (Fe) and sulphur (S)) with synchrotron-based high-resolution elemental mapping of P, manganese (Mn), Fe and S to determine in which mineral forms P is sequestered. We found high amounts of sedimentary Mn, Fe-oxyhydroxides (Feox) and P in the surface sediments upon an increase of BW O2. Electrogenic sulphur oxidation (e-SOx), by the recently discovered cable bacteria, might further contribute to the enhanced formation of Mn, Feox and P compounds in these surface sediments. We suggest that Mn(II) phosphates, Mn-oxyhydroxides (Mnox) and Mn-carbonates might play an important role in the sequestration of P in the GoF. The sulphidic sediments are not effectively sequestering P due to the reductive dissolution of Feox and Mnox and a subsequent release of P to the overlying water during hypoxic intervals. Our results indicate that the organic matter serves as the only permanent burial pathway for P in the GoF, regardless the redox state.