Déficit de oxígeno y temperatura en superficie en cavidades de la zona centro de la Península Ibérica
- R. Pérez-López
- S. Sánchez-Moral
- T. Martín-Pozas
- A. Fernández-Cortés
- S. Cuezva
- A. Marcos-Nuez
ISSN: 1576-5172
Año de publicación: 2021
Título del ejemplar: X Congreso Geológico de España
Número: 18
Páginas: 491
Tipo: Artículo
Otras publicaciones en: Geotemas (Madrid)
Resumen
Air samplings and an environmental monitoring program have been conducted at Sima CJ-3 (-80 m, Soria) between 2014 and 2019, and Sima de la Tierra Muerta (-45 m, Cuenca) from 2017 to 2019. In both cavities, O2 values were detected well below the usual ones (20-21%) in these environments. In the CJ-3 the minimum value was 16% at -75 m deep. In the Sima de la Tierra Muerta, the lowest oxygen value was 16.1% at -45 m. The data show a downward trend in the O2 profile since 2014, related to the increase in the average monthly temperature outside the cavities that causes a decrease in air exchange rates between the underground environment and outside atmosphere. This lower ventilation rate favours the accumulation of high concentrations of CO2 inside (4.5%) and cause seasonal under-oxygenation by replacing of O2. The isotopic signal of the CO2 source (δ 13CO2) ranging from -21.5‰ to -24,0 ‰, could indicate that CO2 can be generated mainly in the immediately superior vadose zone and be related to special microbial activity of hypoxic cavities, which is different from that produced in other shallower oxygenated cavities.