Analysis of long- and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano,Lanzarote, Canary Islands |
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| Authors: | Pedro A Hernández Germán Padilla Eleazar Padrón Nemesio M Pérez David Calvo Dácil Nolasco Gladys Melián José Barrancos Samara Dionis Fátima Rodríguez Hirochika Sumino |
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| Institution: | 1. Environmental Research Division, ITER, 38611 Granadilla de Abona, Tenerife, Canary Islands, Spain;2. Instituto Volcanológico de Canarias (INVOLCAN), 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain;3. Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan |
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| Abstract: | Reported herein are the results of eight soil CO2 efflux surveys performed from 2006 to 2011 at Timanfaya Volcanic Field (TVF), Lanzarote Island with the aim of evaluating the long- and short-term temporal variations of the diffuse CO2 emission. Soil CO2 efflux values ranged from non-detectable up to 34.2 g m−2 d−1, with the highest values measured in September 2008. Conditional sequential Gaussian simulations (sGs) were applied to construct soil CO2 efflux distribution maps and to estimate the total CO2 output from the studied area at the TVF. Soil CO2 efflux maps showed a high spatial and temporal variability. Total CO2 emission rates ranged between 41 and 518 t d−1, February 2011 (winter) being the season when maximum diffuse CO2 emission rates were observed. To investigate the influence of external variables on the soil CO2 efflux, a geochemical station (LZT01) was installed at TVF to measure continuously the soil CO2 efflux between July 2010 and March 2012 Since external factors such as barometric pressure, rainfall, soil water content, soil and air temperatures, and wind speed influence strongly the observed soil CO2 effluxes, multiple regression analysis was applied to the time series recorded by the automatic geochemical station LZT01 to remove the contribution of these external factors. The influence of meteorological variables on soil CO2 efflux oscillations accounts for 13% of total variance, with barometric pressure, rainfall and/or soil water content having the most influence in the control of the soil CO2 efflux. These observations along with the results from the eight soil gas surveys performed at TVF indicate that the short and long-term trends in the diffuse CO2 degassing are mainly controlled by environmental factors. |
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