| Autor: |
Fernandez-Cortes, Angel, Cuezva, Soledad, Garcia-Anton, Elena, Alvarez-Gallego, Miriam, Pla, Concepcion, Benavente, David, Cañaveras, Juan, Calaforra, Jose, Mattey, David, Sanchez-Moral, Sergio |
| Předmět: |
|
| Zdroj: |
Environmental Earth Sciences; Dec2015, Vol. 74 Issue 12, p7715-7730, 16p, 1 Chart, 5 Graphs, 3 Maps |
| Abstrakt: |
A comprehensive environmental monitoring program was conducted in the Ojo Guareña cave system (Spain), one of the longest cave systems in Europe, to assess the magnitude of the spatiotemporal changes in carbon dioxide gas (CO) in the cave-soil-atmosphere profile. The key climate-driven processes involved in gas exchange, primarily gas diffusion and cave ventilation due to advective forces, were characterized. The spatial distributions of both processes were described through measurements of CO and its carbon isotopic signal (δC[CO]) from exterior, soil and cave air samples analyzed by cavity ring-down spectroscopy (CRDS). The trigger mechanisms of air advection (temperature or air density differences or barometric imbalances) were controlled by continuous logging systems. Radon monitoring was also used to characterize the changing airflow that results in a predictable seasonal or daily pattern of CO concentrations and its carbon isotopic signal. Large daily oscillations of CO levels, ranging from 680 to 1900 ppm day on average, were registered during the daily oscillations of the exterior air temperature around the cave air temperature. These daily variations in CO concentration were unobservable once the outside air temperature was continuously below the cave temperature and a prevailing advective-renewal of cave air was established, such that the daily-averaged concentrations of CO reached minimum values close to atmospheric background. The daily pulses of CO and other tracer gases such as radon (Rn) were smoothed in the inner cave locations, where fluctuation of both gases was primarily correlated with medium-term changes in air pressure. A pooled analysis of these data provided evidence that atmospheric air that is inhaled into dynamically ventilated caves can then return to the lower troposphere as CO-rich cave air. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Full text from SpringerLink