Identifying CO2 Seeps in a Long-Dormant Volcanic Area Using Uncrewed Aerial Vehicle-Based Infrared Thermometry: A Qualitative Study

Ciomadul is a long-dormant volcanic area in the Eastern Carpathians of Romania. The study site, the Stinky Cave, and the surrounding areas are well-known for CO2, and H2S seeps. The gases from these seeps come with high flux and are of magmatic origin, associated with the volcanic activity of Ciomadul. In this study, an Uncrewed Aerial Vehicle coupled with a thermal infrared sensor is used to identify new seeps. In order to achieve this, we carried out several field campaigns, coupling image acquisition with the creation of digital outcrop models and orthomosaics. The study was carried out at low ambient temperatures to identify strong thermal anomalies from the gasses. Using this qualitative study method, we identified several new seeps. The total emission of the greenhouse gas CO2 in the Ciomadul area and other similar sites is highly underestimated. The practical application of this method will serve as a guide for a future regional rollout of the thermal infrared mapping and identification of CO2 seeps in the area

Geochemistry of dissolved gases from the Eastern Carpathians - Transylvanian Basin boundary

We show the results of a study on the volatiles dissolved in mineral waters discharged over a 200km-long transect along the Rodna-Bârgău area and Călimani-Gurghiu-Harghita volcanic chain (Eastern Carpathians, Romania). All of the collected mineral water samples carry dissolved gas with carbon dioxide content up to 1.99cm3STP/gH2O, and helium content up to 2.3×10-5 cm3STP/gH2O. Carbon (δ13CTDIC total dissolved inorganic carbon, ranging from -15.6 to 5.32‰ vs. VPDB), He systematics (He isotopes in the range of 0.38-0.99 Ra, Ra=air-normalized 3He/4He ratio) and CO2/3He ratio spanning over four orders of magnitude from MORB-like values of 2.92×109 to crustal-type values of 3.02×1013, coherently indicate the presence of fluids from different crustal sources (e.g. sediments, hydrocarbon reservoirs) besides minor, but detectable contributions of mantle/magmatic-derived fluids (up to 16.45%). Our investigations show that the wide range of chemical and isotopic composition can be explained in terms of mixings among different gas sources feeding the groundwater and the contemporary occurrence of gas-water interactions like degassing and deposition of carbonates, affecting the circulating waters after their infiltration. © 2016

Compositional measurement of gas emissions in the Eastern Carpathians (Romania) using the Multi-GAS instrument: Approach for in situ data gathering at non-volcanic areas

The Multi-GAS, a robust and low-cost instrument for real-time in-situ gas measurements, has previously been used mainly for compositional measurements of active volcanic plumes. Here we demonstrate novel use of a specially designed Multi-GAS instrument adapted to low temperature degassing areas. We performed compositional measurements in the Eastern Carpathians on dry and bubbling gas emissions using a sensor kit that allows measurement of CO2, CH4 and H2S (three major components of low-temperature hydrothermal/volcanic manifestations). Our results demonstrate good agreement between Multi-GAS measurements and independently obtained CO2 concentrations from gas chromatography. We also provide some novel H2S information for some anomalous sites, which we relate to possible alteration processes of sulphide minerals. The use of Multi-GAS in such environments could open new possibilities for data collection at non-volcanic areas and exploration of mineral resources. Moreover, it can also be a useful tool in exploration surveys to select the best sampling sites for more detailed laboratory measurements

In-situ analysis of the gas-emissions of the Eastern Carpathians (Romania) using the Multi-Gas instrument

The Multi-Gas instrument is an important tool for the investigations and monitoring of volcanic systems world- wide, because it can be easily placed on a volcano and can provide real-time data on the compositional changes of the fluids that are released (Aiuppa et al., 2005, Shinohara et al., 2005). We used a specially designed Multi-Gas to gather in situ compositional information about low-temperature, CO2-rich gases, emerging from different manifestations like dry gas emissions (mofettes), bubbling pools and springs. The instrument is equipped with two IR sensors for CO2 (0-100%) and CH4 (0-7%) and one electrochemical sensor for H2S (0-200 ppm). The Multi-Gas was used during several field surveys between September-November 2018 across the Eastern Carpathians area, where a total of 69 gas emissions were investigated for their CO2, CH4 and H2S concentrations. Concentrations of the different gas-species varied according to the geological context. The CO2 concentrations varied between 0.96 and 98.08 %. The highest values were measured in the the volcanic area of Ciomadul, the youngest volcano of the Eastern Carpathians (32 kyr, Harangi et al., 2015), characterized by high CO2 gas output up to 8700 t/year (Kis et al., 2017). High values were measured also in the thrusted and folded area of the Carpathian Flysch and, suggesting the tectonic control over the appearance of the gas emissions. The CH4 concentrations ranged between 0.21 and 6.76% and were higher at hydrocarbon-prone areas, such as the sedimentary deposits of the Transylvanian Basin and Carpathian Flysch. In these cases the CO2 concentrations were low (up to 4.6%). The concentrations of H2S were higher at the volcanic area of Ciomadul, reaching values above the detection limit (∼200 ppm). The Multi-Gas proved to be useful tool in the in-situ investigation of cold gas emissions of the Eastern Carpathians, being efficient especially for the measurement of the H2S concentrations that are very sensitive for oxidation processes. This research belongs to the scientific project supported by the OTKA, K116528 (Hungarian National Re- search Fund), the EU and Hungary, co-[U+FB01]nanced by the European Regional Development Fund in the project GINOP-2.3.2-15-2016-00009 ‘ICER’, New York Hungarian Scientific Society and the Deep Carbon Observatory. Aiuppa, A., Federico, C., Giudice, G., Gurrieri, S. 2005, Chemical mapping of fumarolic field: La Fossa Crater, Vulcano Island (AeolianIslands, Italy), Geophysical Research Letters, Vol. 32, LI3309 Harangi, Sz., Lukács, R., Schmitt, A.K., Dunkl, I., Molnár, K., Kiss, B., Seghedi, I., Á. Novothny, Molnár, M. 2015, Constraints on the timing of Quaternary volcanism and duration of magma residence at Ciomadul volcano, east-central Europe, from combined U-Th/He and U-Th zircon geochronology, Journal of Volcanology and Geothermal Research, 301, 66-80 Kis B.M. , Ionescu, A., Cardellini, C., Harangi, Sz., Baciu, C., Caracausi,C. & Viveiros, F. 2017, Quan- tification of carbon dioxide emissions of Ciomadul, the youngest volcano of the Carpathian-Pannonian Region (Eastern-Central Europe, Romania), Journal of Volcanology and Geothermal Research, 341, 119–130 Shinohara, H. 2005, A new technique to estimate volcanic gas composition: plume measurements with a portable multi-sensorsystem, Journal of Volcanology and Geothermal Research, 143, 319– 33

Quantification of carbon dioxide emissions of the Ciomadul, the youngest volcano of the Carpathian-Pannonian Region (Eastern-Central Europe, Romania)

We provide the first high-resolution CO2 flux data for the Neogene to Quaternary volcanic regions of the entire Carpathian-Pannonian Region, Eastern-Central Europe, and estimate the CO2 emission of the seemingly inactive Ciomadul volcanic complex, the youngest volcano of this area. Our estimate includes data from focused and diffuse CO2 emissions from soil. The CO2 fluxes of focused emissions range between 277 and 8172 g d−1, corresponding to a CO2 output into the atmosphere between 0.1 and 2.98 t per year. The investigated areas for diffuse soil gas emissions were characterized by wide range of CO2 flux values, at Apor Baths, ranging from 1.7 × 101 to 8.2 × 104 g m−2 d−1, while at Lăzărești ranging between 1.43 and 3.8 × 104 g m−2 d−1. The highest CO2 focused gas fluxes at Ciomadul were found at the periphery of the youngest volcanic complex, which could be explained either by tectonic control across the brittle older volcanic edifices or by degassing from a deeper crustal zone resulting in CO2 flux at the periphery of the supposed melt-bearing magma body beneath Ciomadul. The estimate of the total CO2 output in the area is 8.70 × 103 t y−1, and it is consistent with other long (N10 kyr) dormant volcanoes with similar age worldwide, such as in Italy and USA. Taking into account the isotopic composition of the gases that indicate deep origin of the CO2 emissions, this yields further support that Ciomadul may be considered indeed a dormant, or PAMS volcano (volcano with potentially active magma storage) rather than an inactive one. Furthermore, hazard of CO2 outpourings has to be taken into account and it has to be communicated to the visitors. Finally, we suggest that CO2 output of dormant volcanic systems has to be also accounted in the estimation of the global volcanic CO2 budget