The development of in situ chemical sensor plays a key role in understanding of chemical and biological processes in the ocean. There are few chemical sensors for deep sea use and their accuracy and resolution are not satisfying for the purpose of chemical oceanography. ISFET (Ion Sensitive Field Effect Transistor) is a semiconductor that can measure ion concentrations in aqueous media. Since the ion selectivity of ISFET depends on the membrane attached onto its surface, H⁺, P_CO2, Ca⁺ , K⁺ and Na⁺ can be measured when aproper ion sensitive membranes is used. Furthermore, the silicon chip technology will make it possible to develop the integrated chemical analysis system using ISFET sensor and micro actuator. In this article, we introduce an in situ pH sensor newly developed using ISFET and present its possible application to oceanography.

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Gaseous hydrocarbons were analyzed for interstitial water and soil gas of peat samples from Tateyama, Midagahara, Japan in order to clarify the relationship between the redox coditions and light hydrocarbons of terrestrial origin. Methane, C₂-C₄ alkanes and C₂-C₃ alkenes were recognized nevertheless high redox conditions, in which dissolved oxygen was saturated with the atmosphere. However, light hydrocarbon contents, particularly methane, are extremely low in comparison with other peat land such as Oze and Miyadoko moors. On the basis of the abundance ratios of alkanes and ethylene relative to methane, ethane/ ethylene, and i-butane/n-butane, it is suggested that where methane-bearing interstitial water discharged into aerobic environments microbial methane oxidation may occurred.

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In order to understand the characteristics of dissolved fluorescent substances in the Yodo River system, fluorescence properties of these substances were investigated by three-dimensional excitation emission matrix (3-D EEM) spectroscopy. The water samples were characterized by three excitation (Ex.)/emission (Em.) maxima in the winter and spring seasons. Relative fluorescence intensities of Ex./Em. maxima increased down stream. Positive relationships among relative fluorescence intensities of the three Ex./Em. maxima and dissolved organic carbon, nutrients in the river and pore waters were observed. The results suggest that the major sources of the fluorescent substances are waste water effluents as well as leaching from bottom sediments. Negative relationships between relative fluorescence intensities and chlorophyll a in the spring season, suggesting that these substances are not directly originated from the biological activity in this river system. The peak positions of the fluorescent substances in the river water samples corresponded to the protein and fulvic-like substances which have been reported.

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In Japan, we can study many kinds of volcanic products by volcanic eruption, such as lavas (magma on the earth's surface), volcanic rocks, volcanic ashes, volcanic sublimates, magmatic waters, volcanic hot springs, geysers, radioactive springs, volcanic gases, alteration products, etc. Observation and measurement on the nature and chemical properties of volcanic products in many volcanic areas and hot spring areas in Japan, and model experiments in the laboratory on the formation and properties of artificial magmas, artificial magmatic gases, artificial volcanic sublimates, artificial magmatic waters, artificial strongly radioactive springs have been carried out to explain the formation of volcanic emanations from magmatic emanations by the differentiation of magmatic emanation.

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