Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing.

摘要: Abstract Radon-222 and carbon dioxide concentrations have been measured during several years at points in the atmosphere of an underground limestone quarry located a depth 18 m Vincennes, near Paris, France. Both showed seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m−3 summer about 800–1400 Bq m−3 winter, indicating winter ventilation rates varying 0.6 2.5 × 10−6 s−1. Carbon 0.9 1.0% summer, 0.1–0.3% winter. can be corrected for natural using temperature measurements. The obtained model also accounts variation dioxide. After correction, radon still exhibit significant temporal variation, mostly associated with atmospheric pressure, coupling coefficients −7 −26 Bq m−3 hPa−1. This accounted barometric pumping model, coupled including internal mixing as well. residual poorly correlated between different points, standard deviations 3 6%. study shows that cavities understood satisfactory level detail non-linear time-dependent modelling. It is important understand limitations their modelling monitor properties or artificial settings, able assess existence new processes, example preparatory phases volcanic eruptions earthquakes.