New Zealand Journal of Marine and Freshwater Research abstracts

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Optically pure waters in Waikoropupu (`Pupu') Springs, Nelson, New Zealand

R. J. DAVIES-COLLEY
D. G. SMITH

National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11-115
Hamilton, New Zealand

Abstract  We have made in situ observations of the optical properties of Waikoropupu ("Pupu") Springs, Nelson, New Zealand. Visual clarity was measured in the horizontal direction over a sight path "folded" using a plane mirror so as to accommodate the sighting range within the 35 m wide main springs basin. An average black-body visibility of 63 m was obtained, the highest yet reported for any fresh water, and close to the theoretical maximum for optically pure water. Measurements with a beam transmissometer were consistent with the visibility observations. As well as ranking among the very clearest waters in the world, these spring waters are virtually indistinguishable from pure water as regards their spectral irradiance attenuation in the ultraviolet and beam attenuation in the green region of the spectrum, undetectably low content of yellow-coloured organic material, and remarkable blue-violet colour.

Keywords  optical water quality; clarity; colour; Waikoropupu Springs

New Zealand Journal of Marine and Freshwater Research, 1995: Vol. 29: 251-256

0028-8330/95/2902-0251 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (845K); (scanned from paper original: notes about this process)

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