In Situ Technologies

The sediment surface is characterized by steep gradients and an extensive spatial and temporal heterogeneity. Measurements with high temporal and spatial resolution are crucial for the understanding of early digenesis, microbe-environment interactions and benthic fluxes. To determine microbial conversion rates in sediments and to get insight in their regulation, activity measurements must be complemented by characterization of the habitat, its microenvironments, determination of transport phenomena and, ideally, substrate availability measurements. The microprofiler unit enables the in situ quantification of such processes in environments where core retrieval severely alters the sediment, such as in gas-laden cold seeps, the deep sea, or highly dynamic environments. more ...

In the highly heterogeneous ocean ecosystem, the sediment- bottom water interface represents a boundary zone that connects the two oceanic realms - the sediment and the water column. At the seafloor the sediment- water interface is one of the most important transition zones for solute exchange, both in time and space. The benthic chamber module enables in situ measurements of the total exchange rates (e.g oxygen, methane, nutrients, DIC) between the sediment and the water column. This measurement integrates all relevant solute transport processes (diffusion, advection and fauna-mediated transport). more .....

The distribution of oxygen in marine sediments is often highly heterogeneous due to factors like advection, bioturbation / bioirrigation, plant roots and benthic photosynthesis. The planar optode module enables in situ exploration of the oxygen dynamics at the sediment surface. The sediment oxygen distribution is recorded as 2D-images with a high temporal resolution giving insight to the spatial heterogeneity and its evolution over time. more ......

The sediment-water interface is one of the most important boundary layers of the earth system with crucial filter functions for the mass exchange between the seafloor and the water column. One of the most important exchange processes across this layer is the oxygen flux, which is a predominant control factor for the biogeochemical activity in the sediment. The eddy correlation system (ECS) allows measuring exchange rates across the water-sediment interface in a non-invasive manner providing direct measurements with temporal resolution of minutes and a spatial resolution of several meters. more ....

Oxygen concentrations in the marine environment are highly variable on a wide span of temporal and spatial scales. Thus, for monitoring oxygen dynamics in the sea, continuous measurements at many different positions are often desirable. The MuFO was developed to enable multiple oxygen measurements in the watercolumn and in sediments with a high temporal resolution in combination with high degree of spatial flexibility. more .....