Project GB1

G. Fischer, G. Mollenhauer and V. Ratmeyer
R. Schlitzer, M. Iversen, N. Nowald, A. Basse, M. Zabel, H. Ploug, W. Balzer, J.-B.-Stuut, K. Baumann, K. Zonneveld, D. Unger

Background

The efficiency of particle transport between the surface and the deep ocean is largely controlled by the composition and physical characteristics of larger organic-rich particles such as marine snow. However, our knowledge about the distribution of particles, their size and density and the settling behavior of various biogenic and lithogenic components as well as the variable alteration of organic carbon in the water column is still poor. Thus, our main objective is to obtain a mechanistic and quantitative understanding of the processes involved in the degradation of organic matter during sinking of particles in the water column.
 
The coastal upwelling zone off Mauritania (Cape Blanc) and the open ocean region north of the Cape Verde Islands are ideal natural laboratories for examining how ballast minerals influence sinking rates and the distribution of particles and how this affects element fluxes and remineralization rates in the water column over various time scales. At present, we have an exceptional particle flux record from the area off Cape Blanc spanning from 1988 until now. Our approach will combine microbial experiments, biomarker, isotopic, in situ optical, deep ocean flux, remote sensing and modeling studies. The impact of sinking rates on transport pathways of organic carbon will be simulated with a Regional Oceanic Modeling System (ROMS) coupled with built-in ecosystem-aggregation modules. This will also allow quantification of cross-shelf organic carbon export off NW Africa from seasonal to decadal time scales.