A Benthic chamber with electric stirrer mixing

Abstract

Benthic chambers incorporating electric stirrer mixing have been designed and tested and have proven reliable during seven 18-31 day, 4300m ocean deployments. The chambers are 21 cm diameter by 31 cm long acrylic tubes sealed with pvc lids. A stepper motor and pressure tolerant electronics contained within the lids are magnetically coupled to stirring paddles to provide mixing within the chambers. The stirrers exhibit stable mixing rates and uniform speeds between chambers, require less than 1/3 watt of power, and are maintenance free. Laboratory calibration of stirring and mixing characteristics demonstrate that areal averaged equivalent seawater-sediment boundary layer thickness can be set to agree with in situ measured values.