Project B2 (2001 - 2005)

Origin, reactivity, and transformation of particulate organic material in the benthic boundary layer in high productivity systems

The scientific work in former project B2 of the Research Center Ocean Margins focused on biogeochemical investigations at the sediment water interface. Rates and pathways of benthic carbon degradation depend on the quality and quantity of carbon flux to the ocean floor. However, the importance of the quantity, sources, quality and composition of the settling organic material (export production) still requires investigation.

Particle transport at a continental margin
For the detailed analysis of the lateral transport of suspended particles in the Bottom Nepheloid Layer a new sampling device (”Beawis” - the Bottom Water Sampler, Fig.1) was build in cooperation with the company KUM from Kiel. It was especially designed to collect water samples from different heights above the seafloor. In addition to model the flow field, geochemical and geophysical investigations on suspended material and surface sediments, were important components to quantify lateral and vertical transport processes.
More information concerning this aspect of the project can be found here.

... to define and quantify the reactivity of organic matter
- that is a major subject for a lot of biogeochemical and geological studies. Therefore, a major focus of the project lay on the relation between microbial controlled flux rates and organo-geochemical indices. Classical geological and biogeochemical methods as well as new degradation indices were applied to characterise the organic matter and determine aerobic and anaerobic flux-rates with ex- and in-situ experiments.
To elucidate effects of both the quality (reactivity) and quantity of organic material on the surface-sediment ecosystem, organic matter of different qualities (fresh and altered algal material, both isotopically labeled, and local shelf sediment) was used. Changing pathways, reaction rates and reaction times were determined by changing the respective conditions. Experiments included in-situ incubations in benthic sediment chambers of a free-falling lander (see Fig. above) and ex-situ incubations of whole sediment cores.