A telemetering system for monitoring aqueous polythionates in an active crater lake

We have developed an in-situ monitoring system for aqueous polythionates in the Yugama crater lake at Kusatsu-Shirane volcano. A commercially availabl e nitrate-selective electrode has a Nemstian response to the concentration of polythionates in solution in the range of pH 2.5-11. However, many activ e crater lakes contain highly acidic water (pH ranges from 0.2 to 2). The m onitoring system reduces the acidity of the lake water to pH 4 without chan ging the concentration of polythionates using a high efficiency cation-exch ange membrane technique. The monitoring system was placed in a submersed st ation, because the Yugama surface lake water freezes in mid-winter. The sys tem is described and preliminary data are reported. (C) 2000 Elsevier Scien ce B.V. All rights reserved.