No abstract

<p>The relative concentrations of photosynthetic and photoprotective pigments provide important information about the physiological state of the plant and are determined, among other things, by the lighting regime and the presence of nutrients. Relative composition of the pigments is depending on the physiological response of the plant to external influences. In most cases, when an on-line in-situ analysis is required, only the main pigments are measured: Chla, Chlb and a rough estimate of the "total carotenoids" in higher plants, but such an estimate may not always be reliable. Differential Optical Absorption Spectroscopy (DOAS) is known for its applications for the trace gases measurements in the atmosphere sciences; however, no application has been found for the determination of color pigments for plant extracts. For the correct application of the DOAS method, it is necessary to determine the appropriate optical thickness of the sample under study, the fitting intervals for analysis, as well as a set of absorption cross sections for the target pigments.</p><p>Purpose of the work is to determine the appropriate settings for the retrieval of concentrations of colored pigments employing the DOAS method by investigating the sample of pine and spruce needles extraction. The relevance of the work consists in the development of a new method for analyzing transmission spectra, which does not require the creation of specialized software, since programs for analyzing spectra by the DOAS method are available.</p><p>For the spectra registration, Solar M150 spectrometer with Hamamatsu S7031-1006S detector has been used, the transmission spectra recorded in the 330 - 750 nm range, and pure acetone employed as a solvent. The paper presents the results of DOAS-analysis of extracts of various coniferous samples, from which it was possible to retrieve the contents of Cha, Chb, B,b-carotene, B,e-carotene, and small amounts of Phaeophytin-a, Neoxanthin. Optimal settings for the DOAS-analysis and experimental setup details for photosynthetic and photoprotective pigments retrieval are discussed.</p>

<p>Drying out of coniferous trees (Picea abies) due to bark beetle infestation and other diseases leads to a high rate of conifers mortality. The coniferous forests in Belarus are largely exposed to damage by the bark beetle, the early symptoms of which are the changes in the color and loss of shine of the needles.  </p><p>Purpose of the work is to identify drying out stages combining the TripleSat multispectral satellite data (spatial resolution 3.2 m MS, 0.8 m PAN, bands R, G, B, NIR) for the test coniferous forest area in Belarus (53.65419º N, 27.640213º E) with quasi-synchronous airborne photo-spectral measurements which have been used as a reference data. Airborne measurements of reflectance coefficient function of underlying coniferous trees have been carried out by employing two spectrometers (wavelength range 400-900 nm, spectral resolution 4.3 nm) and photo-camera (visible range, FOV 50º) mounted on board of Diamond DA40NG aircraft in nadir geometry.  </p><p>Airborne RGB-images have been used for visual identification of the type of underlying surface and for subsequent training data set formation. Training data consist of several sets (10 – 20) of vegetation indexes for each type of underlying surface. The linear discriminant analysis (LDA) classification algorithm has been applied in this study for distinguishing the conifers drying out stages. A set of vegetation indices evaluated for each reflectance coefficient function has been applied as input data for LDA classification algorithm.</p><p>LDA classification algorithm has been employed to the TripleSat image for identification drying out stages of coniferous trees. The reference data for LDA classification algorithm of the TripleSat image included the combination of coordinates and corresponding types of underlying surface obtained from the results of the airborne experiment classification. A set of vegetation indices has been derived for each pixel of the image and used as input data for LDA algorithm; also vegetation indices calculated for the reference pixels have been applied for training data set formation.</p><p>The classification accuracy of three conifers drying out stages based on the airborne experiment is estimated to be in a range of 27 - 74%. The verification of TripleSat classification results has been performed by visual comparison with high resolution aerial images.</p>

<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>