niskin watersampler 1.pptx

nis kin water sampler

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.