1. Niskin water - sampler
Name – Soumya Ranjan
gouda
Sl no - 001
2. INTRODUCTION
Niskin water sampler is invented by an American
scientist ShaleNiskin in 1966.There widely used than
the Nanson bottle in modern ocean- water sampling
activities.
Niskin water sampler
Niskin water sampler for 1.2 litre size weight
4.5lbs (2kg) , length about 76.2 cm can be used
on a rosette or independely on a cable with a
messenger .
A niskin water bottle is a plastic cylinder with
stoppers at each end in order to seal the bottle
completely.
This device is used to take water samples at a
desired depth without the danger of mixing with
water from other depths.
3. Open Niskin bottles are attached to a cable and
lowered to water depths where seawater
samples are to be obtained for chemical
analysis. A metal messenger “trips” each bottle
on the cable individually, causing it to fill with
water and close securely.
4. Water collecting bottles are arranged around a rigid, circular frame in a
rosette pattern. Technicians are able to close the bottles individually as the
array is lowered or raised through the water column.
Sampling Depths
Chemists must establish the exact sampling depth for each bottle. Otherwise,
the analytical work, no matter how accurate, is of limited use in determining
the exact chemical structure of the water column.
5. Operating and attachment
system
The system locks the bottle when the messanger taps it . The
niskin bottle can also be attached to a main line off up to 6 mm
thick or to an oceanographic rosette.
Analytical procedures
Analytical procedure reveal temperature and salinity of water. recorded in the reversing
thermometers which are fastened to water-sampling bottles, Better precision (up to 0.0001°C) is
obtained by using temperature-sensitive materials, such as quartz crystals, which vibrate at
frequencies that depend on temperature. These signals are transmitted electronically to the ship.
This allows the temperature of the water to be monitored continuously as the instrument is
lowered.
6. Because the composition of seawater is constant, chemists traditionally have determined
water salinity by chemical titration-the process of standardizing silver nitrate against a
normal seawater sample of known chemical composition.The electrical conductivity of
seawater, which is proportional to the total concentration of dissolved ions, is now used
routinely to determine salinity rapidly.
construction
The water sampler is fully made of PVC and its interior is totally free from
metal parts. Top- and bottom plates are held together with a sea water
resistant rubber string, and a drop messenger releases the closing
mechanism. Because of the open construction during the deployment, the
Niskin bottle can be used at any depth.
7. The water sampler can be used singly (by use of 1 pc 60.002 Centre hanger for single
ocean water sampler) or in series and closes correspondingly. The Niskin water bottles
are also available in a special version, which can only be used with our rosette and
rack system.
