The CO2 content and the temperature of the air have been measured within the scarce soil (although with
relatively high organic matter concentration) which partially covers the carbonate outcrops over the Nerja
Cave (Málaga). General yearly average values of around 850 ppm and 25 ºC have been identified, both
using continuous recording devices and separated measures with portable equipment.
Temperature evolution closely follows that of the outside atmosphere. Spatial variations in CO2 contents
are related with the vegetal cover and with the soil depth. Seasonal variations are important, with a
maximum of more than 1000 ppm in May (main vegetation development) and minimum (around 350-
500) in December. Daily oscillations have also been identified, ranging up to more than 600 ppm in the
period of maximum CO2 production. These results agree with estimates based in hydrogeochemical
modelling as well as in the TOC content of drip water to the cav