Campionamento Acque con Bottiglie Niskin
The niskin bottle is a device used for obtaining samples deep or subsurface water.
The bottle, more precisely a metal or plastic cylinder, is lowered on a cable into the sea and when it has reached the required depth, a brass weight called a "messenger" is dropped down the cable. When the weight reaches the bottle, the impact tips the bottle upside down and trips a spring-loaded valve at the end, trapping the water sample inside. The bottle and sample are then retrieved by hauling in the cable. More modern versions of the Niskin bottle have electronic closure. The bottles can be single or mounted on rosette.