The Niskin and Go-Flo bottles

1. The Niskin and Go-Flo bottles are used to take water samples at the required depths. The Niskin water sampling bottle is tubular and is available in various sizes (5, 10, 30 litres, etc.). The bottle is lowered into the sea on a steel cable, open. Once the required depth has been reached, a 'messenger' weight is slid along the cable to the bottle and drops onto the closing mechanism. The now hermetically sealed bottle is then brought back up to the surface. The Go-Flo water sampling bottle is used whenever uncontaminated samples need to be taken, for instance for the chemical analysis of trace metals in sea water. The Go-Flo bottles are closed when they are lowered into the water column and open automatically at a depth of about 10 metres. As a result, these bottles are neither contaminated on deck nor as they are lowered into the water, by the uppermost layer of the seawater surface that is contaminated by interaction with the air. Several Niskin or Go-Flo bottles (12 or 24) can also be attached to a rosette, which is then lowered into the water column along with an 'STD' measuring system. In this case, the bottle closing mechanisms are activated by the STD system each time a required depth is reached.

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