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A study of the seasonal changes of the water mass of Christchurch Harbour, England

Published online by Cambridge University Press:  11 May 2009

J. W. Murray
Affiliation:
Department of Geology, University of Bristol

Extract

Detailed sampling of the bottom water of Christchurch Harbour, England, was undertaken in conjunction with a study of the living and dead foraminiferids (to be described later). The Harbour is a shallow estuary with an unusual tidal regime of four high tides daily. During the winter the flow of fresh water from the rivers prevents sea water from entering much of the estuary. During the spring, summer and autumn, when drier conditions prevail on land, the sea enters the estuary as a salt wedge and there is pronounced salinity stratification. In addition to determinations of chlorinity, pH, dissolved oxygen and temperature, analyses of calcium were made during the spring, and of calcium and magnesium in the summer. It was found that calcium was preferentially removed from the bottom water, thus upsetting the calcium-chlorinity ratio. The cause of the calcium removal is thought to be biological activity. Magnesium was not affected by this process. A discussion of the results is presented and it is suggested that biological removal of calcium from the bottom water is particularly well developed in Christchurch Harbour owing to the extensive areas of shoal water favouring biological activity. Estuaries of this type may not be very common.

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 1966

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