Characteristics of fluctuations in salinity and water quality in brackish Lake Obuchi |
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Authors: | S Ueda H Kawabata H Hasegawa K Kondo |
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Institution: | (1) Institute for Environmental Sciences, Obuchi 1-7, Rokkasho, Kamikita, Aomori 039-3212, Japan Tel. +81-175-71-1454; Fax +81-175-71-1492 e-mail: sueda@ies.or.jp, JP |
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Abstract: | Fluctuations in the salinity and physicochemical characteristics of water quality were surveyed in brackish Lake Obuchi on
the Shimokita Peninsula in Aomori, Japan. The mean salinity in the surface layer in all regions of Lake Obuchi was about 10
psu, whereas in the basin region at depths of greater than 3 m it was 20 psu. Furthermore, all the year round the halocline
was formed at depths of 1–4 m. The maximum density gradient along a vertical axis in the center of the lake was observed at
depths of 1–2 m in summer and 2–4 m in spring and fall. The depth of the maximum density gradient fluctuated with the seasons.
In summer the water in the bottom layer was anoxic, and Fe, Mn, PO4
3−-P, and NH4
+-N supplied from the bottom sediment accumulated at high concentrations below the halocline. Thus, it was observed that the
transfer of substances between the layers above and below the barrier formed by the halocline is suppressed. Although Lake
Obuchi is small and shallow, the inflowing seawater easily resides, and a stable halocline readily forms because of the shape
of its basin, which suddenly deepens on the Pacific Ocean side.
Received: May 24, 1999 / Accepted: September 25, 1999 |
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Keywords: | Brackish Lake Obuchi Salinity Water quality Density gradient |
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