SO2  measurements in volcanic emissions at the Kuril islands by DOAS method

Abstract

<p>One way to predict eruptions is to analyze measurements of the gas composition of volcanic emissions. Depending on the geological features of the rock and the proximity of magma to the earth's surface, the ratio of the concentrations of volcanic gases in emissions (SO<sub>2</sub>, BrO, etc.) may change. For instance, an increase in SO<sub>2</sub> content in emissions may indicate the proximity of magma to the surface.</p><p>The main problem of measuring the gas composition of volcanic emissions is the relatively high health risk for the researcher, due to the high content of air pollution near the research object. In this regard, portable instruments that allow remote measurements of the gas composition of volcanic emissions are relevant.</p><p>To solve this problem, the authors have developed a portable instrument DEVI (Doas Expedition Volcanic Instrument), which makes it possible to retrieve the slant column of gases in volcanic emissions by the DOAS method. DEVI's main optical module is a spectrometer, designed for the concave diffraction grating (R = 60 mm, 2581 lines / mm) and Toshiba TCD1304DG detector. Optimization of the optical scheme parameters has been carried out aiming to minimize the width of the instrumental function for the spectral range 280-340 nm and the entrance slit 50 × 50 μm.</p><p>The handmade instrument DEVI was applied in an expedition to the Kuril Islands during the period 31.07-13.08.2021, aiming to obtain data about the gas composition of volcanic emissions. The paper will present the results of processing the spectra of the celestial sphere near the volcanoes of the Kuril Islands in order to retrieve SO<sub>2</sub> and BrO slant columns by DOAS method. In addition, the preliminary mathematical processing of raw spectra will be discussed in order to obtain correct data for the slant columns of volcanic trace gases.</p>