Water samples from the surface and the uppermost 60 m are frequently pumped aboard ship using hoses. Chemical analysis and temperature measurements can then be carried out. A continuous stream of water is sucked up and flushed over electrical thermo-salinometers. Surface temperatures and salinities along the cruise track of a vessel are often measured in this way. The water is then passed through autoanalysers and a range of minor constituents, notably ammonium, nitrite, nitrate, phosphate, silicate and organic carbon can be measured giving a complete record for each constituent as the vessel proceeds along its course. Modern autoanalysers can also measure fluorescence indicating chlorophyll content (a measure of primary productivity).
The use of hoses is cumbersome at greater depths, where water-bottles or rosette samplers still have advantages. Bottles are also more suitable than hoses where samples are to be examined for organisms which might be damaged by passage through pumps.
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