After some pilot experiments performed by some members of the network in 2005, with Japanese equipment and expertise, it was decided by CO2GeoNet to mutualise previous experiences and existing expertise, to develop a new Benthic Chamber (BC) as a shared infrastructure for in-situ experiments related to sub-seabed CO2 storage and ecosystems impact assessments.

The Benthic Chamber system is a powerful, reliable and cost effective tool for performing experiments on small sections of sediment in situ also at medium and large depth in the ocean. For such large depths, there are few real alternatives to making pre-programmed, in-situ exposures, due to the difficulties of bringing sediments up and to shore without too much disturbance of the sediments and the organisms adapted to the deep sea conditions.

In the new Benthic Chamber Lander developed by CO2GeoNet, the sediments within the chambers remain quite undisturbed during CO2 exposures. The experimental conditions can be well controlled both through recordings performed by electrodes and by the water samples withdrawn automatically throughout the experimental period.

 

Phases of the Benthic Chamber Lander set up.

The system allows penetration of each chamber to a predetermined depth of sediment so that the same headspace volume of water and other physical parameters can be pre-set and kept as equal as possible.

The size of the chambers is such that the system is suitable for testing effects of CO2 on sediment geochemistry and small organisms, especially bacteria and nanobenthos but also meiofauna. The results obtained so far indicate stimulation or inhibition of distinct groups of micro organisms as a consequence of the exposure of the sedimentary environment to elevated CO2 concentrations. They provide valuable input to ecological models for CO2 impact assessments and to evaluate the vulnerability of the bottom ecosystems to potential leaks of CO2.


For more information please contact: Dominique Durand at Norwegian Institute for Water Research