Testing a new quick response oxygen sensor, “RINKO”

Abstract

We evaluated a new quick response dissolved oxygen (DO) sensor “RINKO”, currently under development by JFE Advantech Co., Ltd., to determine its in situ response and applicability to hydrographic and hydrochemical observations in the western North Pacific and in the Sea of Japan. The response time of the RINKO sensor to ambient DO changes was demonstrated at about 1 s in these in situ experiments. RINKO data were calibrated to temperature, pressure, and bottle sample DO data obtained by conventional Winkler method, yielding a precision of < ± 1 μmol kg−1, except in the upper layers of the ocean where vertical DO variations are large. Although the sensor was subject to instrumental drift during the period of a cruise (equivalent to < 6 μmol kg−1 DO) and to pressure hysteresis between downcasts and upcasts (< 4 μmol kg−1 DO), the RINKO sensor is capable of observing continuous vertical DO profiles with a precision that is sufficient for most practical purposes. The RINKO sensor will contribute to an improved understanding of DO variability, providing an expanded DO database with enhanced spatial and temporal resolution.