SIPA: Sinking particles, their production, transfer and transformation.
Cruise MSM 104/1 is carried out as part of the RECEIVER Unit of the Excellence Cluster "The ocean floor- Earths uncharted interface at the MARUM (University of Bremen).
During the cruise groups from the University of Bremen, University of Oldenburg, Alfred-Wegener-Institute in Bremerhaven and the Royal Nertherlands Institute of Sea Research (NIOZ) will perform joint investigations. They will study the formation, sinking, lateral advection and alteration of particulate organic matter and their environmental proxies in the water column and surface sediments in relationship to upwelling intensity, ambient redox conditions and the presence of nepheloid layers. Furthermore, the relationship between dissolved and particulate organic matter (DOM/POM) as well as their age will be studied. Results shall be compared to long-term particle flux and dust records collected by sediment-traps and dust buoys.
The laterally and temporally highly dynamic Cape Blanc upwelling region, is one of the most productive regions in the world and is a key player in the global carbon cycle. Upper water primary production drives the biological pump which is largely controlled by sinking behaviour and lateral transport of marine snow, particle aggregates and faecal pellets. However, today we still largely lack a quantitative understanding about processes that steer production, sinking velocities, lateral transport and transformation of particulate organic matter.
During the cruise the particle export flux out of the upper water column will be sampled with free drifting traps. These traps float with the upper water currents and collect the particle flux at 100, 200 and 400m water depth. These traps will be positioned in an active upwelling cell, an upwelling filament and offshore waters.The temperature, salinity, chlorophyll-a and turbidity content of/in the Water column characteristics will be monitored throughout the surveys by micro-CTD and chlorophyll-a/turbidity sensors that will be connected to the uppermost trap.
To optain insight into the correlation between DOC and POC, the early diagenetic induced molecular alteration of polysaccharids and polysaccharid microfossils during the settling, the aging of POC as well as the lateral and vertical particle transport in deeper water layers, water and sediment will be collected at several depths in the water column with Rosette sampler and in-situ pumps.Special focus lies on sampling of water and sediments from the nepheloid layers.
Last but not least both the MARUM sediment traps and NIOZ dust buoys will be serviced.