>>>> Operating strategy

In order to obtain significant measures of degradation (mineralization and dissolution) rates of particulate material during its descent through the water column we have developped, in collaboration with Metro-Mesures,  an experimental device named as PASS (for PArticles Sinking Simulator, see below Fig.1) to simulate particle sinking down to 4000 m deep.

This equipment will allow sampling of aliquots without decompression of the main culture, nor of the aliquot fraction, so measurements of microbial activities will be processed without decompression at any stage of the experiment. Furthermore, thanks to the high-pressure serial sampler and transfer systems already available in the LMGEM, at any step of the run (i.e. at any simulated depth) we will be able to inject in the culture vessel samples of deep-sea water freshly collected at the same depth without pressure lost. Such processing will simulate the possible recolonization of sinking particles by deep-sea bacteria.

The uniqueness of our equipment allow laboratory simulations of hydrostatic pressure increase experienced by bacteria attached to particles during their sinking throughout the water column.

Figure 1: picture of the PASS (PArticles Sinking Simulator) composed of (1) several water baths where high-pressure bottles (HPB) are rotated to maintain particles in suspension, (2) a cooler to control the temperature of water baths and (3) a programmable computer-driven: Piloted Pressure Generator (PPG). Classically, incubations are made as follows: one HPB is maintained at atmospheric pressure (ATM), and the other is connected to the PPG which increased the hydrostatic pressure to simulate fall through the water column (HP).

To see a short movie of the PASS used to simulate the fall of particle, click here

Contact: Christian Tamburini (tamburini@univmed.fr) ; Tel.: +33 4 91 82 90 53 - Fax : +33 4 91 82 90 51
Mail adress: LMGEM UMR6117, Centre d'Océanologie de Marseille (COM), Case 901, Campus de Luminy, 13 288 Marseille Cedex 9, France