ORIGINAL ARTICLE Assessing cave internal aerology in understanding carbon dioxide (CO 2 ) dynamics: implications on calcite mass variation on the wall of Lascaux Cave (France) N. Houillon 1 • R. Lastennet 1 • A. Denis 1 • P. Malaurent 1 • S. Minvielle 1 • N. Peyraube 1 Received: 15 July 2016 / Accepted: 11 February 2017 Ó Springer-Verlag Berlin Heidelberg 2017 Abstract Carbon dioxide gas is a key component in dis- solution and precipitation of carbonates in karst and cave systems. Therefore, characterizing the internal aerology of a cave is essential to obtain the spatiotemporal distribution of temperature and CO 2 level. In this research, Lascaux Cave (France), an important adorned cavity, was studied. First, the spatiotemporal distribution of CO 2 and tempera- tures were examined using continuous monitoring at a per minute basis. High-resolution spatial measurements (14 PCO 2 locations and 27 locations for temperature) were carried out for a year in the epikarst and the cave (February 2015 to February 2016). The spatiotemporal analysis pre- sents that air and rock temperatures vary for less than a degree Celsius (12.4–12.9 °C). These are controlled by the conduction of the external thermal waves through the overlying calcarenite massif. As a consequence, two sea- sonal internal aerologic regimes were identified: stratifi- cation and convection. These regimes govern the spatiotemporal distribution of the CO 2 levels (1.1–3.7%), showing that this parameter is a good natural marker of the internal air movements. Second, a method was proposed to estimate the calcite mass potentially affected by conden- sation water (dissolution process) and exfiltration water (precipitation process). This method, based on numerical simulations, relies on CO 2 and air and rock temperature spatiotemporal distributions in the cave. Third, the method was applied using the case of the left wall of the Hall of the Bulls (one of the most adorned part of the cave). Results showed that the calcite mass, possibly dissolved, varies from 0.0002 to 0.006 g when the mass potentially precip- itated is higher (from 0.013 to 0.067 g) depending on the aerologic conditions. This method allows determining which alteration process (e.g., precipitation or dissolution) could eventually lead to the largest variation of calcite on the wall. The results can serve as useful data to the cave experts of the French Ministry of Culture and Communi- cation in terms of Lascaux Cave management policies. Keywords Carbon dioxide Á Complex monitoring Á Karst cave aerology Á Calcium carbonate Introduction Carbon dioxide (CO 2 ) is involved in the processes that affect calcite in karst cavities (White 1988). This gas increases the dissolution capacity of condensation water and, potentially, of the exfiltration water. On the contrary, decrease in the partial pressure of CO 2 (PCO 2 ) in the cavity can augment degassing of exfiltration water and calcite precipitation. Hence, it is an important parameter in studying the speleothems (Spo ¨tl et al. 2005; Scholz et al. 2009; Dreybrodt and Scholz 2011; Breecker 2017) and in considering the conservation concerns of adorned caves (Fernandez et al. 1986; Cigna 2002). This water is loaded of dissolved CO 2 after flowing in the soil and the epikarst. CO 2 is produced in the subsurface layer by organic matter degradation and root respiration (Kuzya- kov 2006). The average CO 2 partial pressure in the Earth’s atmosphere is about 0.0407% (NOAA, ESRL Global Monitoring Division (2016), measurements per- formed at Mace Head site, Ireland). This gas accumulates in the pores and the fissures or cracks in the vadose zone (Bourges et al. 2012). Benavente et al. (2010) measured a & N. Houillon nicolas.houillon@u-bordeaux.fr 1 Laboratory I2M-GCE (UMR 5295), University of Bordeaux, Alle ´e Geoffroy Saint Hilaire, Pessac Ce ´dex 33615, France 123 Environ Earth Sci (2017) 76:170 DOI 10.1007/s12665-017-6498-8