Soil CO2 fluxes measured in the Acoculco Geothermal System, Mexico: Baseline emissions from a long-term prospection programme
Por:
Pérez-Zárate D., Santoyo E., Jácome-Paz M.P., Guevara M., Guerero F., Yáñez-Dávila D., Santos-Raga G.
Publicada:
1 ene 2024
Ahead of Print:
1 jun 2024
Resumen:
The Acoculco Caldera Complex is considered a promissory hidden high-temperature geothermal system in Mexico. To support the geothermal prospection of this anomalous area, a comprehensive programme of soil CO2 flux measurements was performed. A long-term measurement programme was conducted to determine the baseline of natural soil CO2 effluxes. Significant efforts were devoted both to measuring the CO2 fluxes between 2015 and 2022 and interpreting their origin. Eighteen soil gas surveys of CO2 were carried out by using the accumulation chamber method. >1200 diffuse CO2 fluxes were measured in six different areas of the Acoculco Caldera. Two areas (Los Azufres and Alcaparrosa) exhibited cold degassing sites, acid-sulphate springs, and gas bubbling in surface water bodies. The soil CO2 fluxes ranged from 1 to 26,000 g m-2 d-1, whereas lower fluxes <29 g m-2 d-1 were determined as the degassing baseline. A total CO2 output of 492 t d-1 km-1 was estimated using an integrated SGS-GSA approach, where the highest total soil CO2 fluxes were obtained for Alcaparrosa (299 t d-1 km-2) compared with Los Azufres (164 t d-1 km-2), and Surroundings (29 t d-1 km-2). Such results agree well with those values measured in other worldwide volcanic and active geothermal ecosystems. The range of CO2 isotopic composition values from -28.83 ‰ to -3.11 ‰, together with their statistical distribution, suggests multiple CO2 production sources feeding soil degassing. The combined interpretation of flux and isotopic data allowed us to identify two distinct gas sources: endogenous and biogenic. The present study highlights the importance of using soil CO2 monitoring to determine baseline emissions at the early exploration stage of geothermal systems. © 2024 Elsevier GmbH
Filiaciones:
Pérez-Zárate D.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Santoyo E.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Jácome-Paz M.P.:
Departamento de Recursos Naturales, Instituto de Geofísica, Universidad Nacional Autónoma de México, Circuito de la Investigación s/n, Ciudad Universitaria, Coyoacán, Ciudad de México, CP 04510, Mexico
Guevara M.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Guerero F.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Yáñez-Dávila D.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Posgrado en Ingeniería, Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco s/n, Morelos, Temixco, 62580, Mexico
Santos-Raga G.:
Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Morelos, Temixco, 62580, Mexico
Posgrado en Ingeniería, Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco s/n, Morelos, Temixco, 62580, Mexico
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