Pathways and time scales of nutrient transports in the Baltic Sea

• Applicant: Dr. Thomas Neumann
• Subject Area: Oceanography
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 93407724

Riverine loads provide significant inputs of nutrients into the Baltic Sea that will ultimately accumulate in the deposition areas. The transport of the dissolved matter is controlled by advection and diffusion, while after transformation of nutrients into particulate organic matter, the dynamics of particles can modify the transport routes. The cycling between fixation of nutrients in particles, their sinking and decomposition into dissolved nutrients is part of the transports and affects their characteristic pathways. In shallow systems like the Baltic Sea, bottom near processes can significantly contribute to the material transports. Close to the sea bed, so-called fluffy layers are generated by sinking, organic aggregates. In this easily erodible layer, material is either transported with bottom near currents or re-suspended, in response to strong wind events. Ultimately these processes carry material to the deposition areas, but little is known about the characteristic pathways and the associated time scales. With the aid of an advanced ecosystem model, issues like transport routes, time scales and fate of nutrients from different sources around the Baltic Sea can be investigated. This becomes possible with a numerical technique for tracking of nutrients, i.e. nutrients of specific sources will be 'ear-marked' and tracked in the physical space and through the food web (phase space). In this project the fate of nutrients from different riverine sources as well as from cyanobacterial fixation of dinitrogen will be investigated.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Wolfgang Fennel