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River Science: Water Temperature

The Half Moon's journey through Long Island Sound and up the Connecticut River takes it through waters of wildly varying depths. In some places, the water is so deep that its ambient temperature often varies considerably between the bottom and the surface.

Although water temperature has relatively little effect on the ship or its crew (with the exception of extreme temperatures, as Captain Hudson understood while battling the polar ice during his arctic expeditions), it can have obvious effects on the local ecology.

Mouse over to snap the sampler shut.
Matt and Michael drop a weight down the Van Dorn sampler line.

On the Half Moon, our students take temperature readings both from samples drawn from the surface (usually as part of comparative temperature studies), and from the water column, which means water collected from different depths at a single location.

To measure ambient temperatures within the water column, we use a Van Dorn sampler. This hollow tube can be lowered to a desired depth in the water. A brass weight is then dropped down an attached line, producing a minor jolt when it reaches the sampler. This bump snaps the tube shut, trapping a water sample inside, which can then be retrieved for analysis.

On this voyage, the research team of Alanna, Jose, and Tyron used the Van Dorn sampler to measure salinity in a water column as a component of their presentation project.

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