Environmental influences on soil CO2 degassing at Furnas and Fogo volcanoes (São Miguel Island,Azores archipelago) |
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| Authors: | F Viveiros T Ferreira J Cabral Vieira C Silva JL Gaspar |
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| Institution: | 1. Centre of Volcanology and Geological Risk Assessment, University of the Azores, Rua Mãe de Deus, 9501-801 Ponta Delgada, Azores, Portugal;2. Department of Economics, University of the Azores, Rua Mãe de Deus, 9501-801 Ponta Delgada, Azores, Portugal |
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| Abstract: | Since October 2001, four soil CO2 flux stations were installed in the island of São Miguel (Azores archipelago), at Fogo and Furnas quiescent central volcanoes. These stations perform measurements by the accumulation chamber method and, as the gas flux may be influenced by external variables, the stations are equipped with several meteorological sensors. Multivariate regression analysis applied to the large datasets obtained allowed observing that the meteorological variables may influence the soil CO2 flux oscillations from 18% to 50.5% at the different monitoring sites. Additionally, it was observed that meteorological variables (mainly soil water content, barometric pressure, wind speed and rainfall) play a different role in the control of the gas flux, depending on the selected monitoring site and may cause significant short-term (spike-like) fluctuations. These divergences may be potentially explained by the porosity and hydraulic conductivity of the soils, topographic effects, drainage area and different exposure of the monitoring sites to the weather conditions. Seasonal effects are responsible for long-term oscillations on the gas flux. |
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| Keywords: | volcanic gases soil diffuse degassing monitoring soil CO2 flux Azores archipelago |
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