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Niskin Bottles
When researchers want to take a sample of seawater from within the water column they often use a relatively simple device called a Niskin Bottle that can be opened at both ends. The open bottle is lowered into the ocean on a wire from a Research Vessel until it reaches a certain depth and then the bottle is closed by a weighted trigger (called a "messenger") that is sent down the cable from the surface. Niskin bottles are often either set up in a series of individual bottles that trigger each other in turn as they close, or they are set up in a circular rosette of as many as 24 bottles attached around a CTD instrument. Either arrangement allows samples to be taken at different water depths in a way that seals off the sample and allows it to be brought to the surface without mixing with water from different depths. Polar researchers sometimes use Niskin Bottles to collect water samples from below the ice . The water collected by Niskin Bottles is used for studying plankton or measuring many physical characteristics such as salinity, dissolved oxygen, nutrient concentrations (such as phosphate, nitrate and nitrite), and dissolved organic and inorganic carbon.
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| A CTD surrounded by a circular rosette of grey Niskin Bottles is lowered over the side of the R/V G.O. SARS during a research cruise along the Mid-Atlantic Ridge. (Mid-Atlantic Ridge Ecosystem Project, MAR-ECO, David Shale) |
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A single small Niskin Bottle is lowered over the side of a research vessel. Note that the device is presently open at both ends so it can take a pure sample at the depth of interest before being sealed off at both ends by a weighted messenger from the surface.
(Cheryl Greengrove, University of Washington, Tacoma; Spring 2005 Estuarine Field Methods Class) |
Click on the links below to see what Census projects use this technology:
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