Human impact in a tourist karstic cave (Aracena, Spain)

 Human intrusion on the Cave of Marvels (southwestern Spain) has produced a series of effects on the water (fall in the level of the pools due to pumping from nearby wells), the air (increased temperature and CO₂ concentration as well as decreased relative humidity) and the rock. In addition, plant colonization, favored by the lighting system, has irreversibly altered numerous speleothems. The processes of degradation are especially intense in the sectors with less air volume and limited ventilation. The analysis of the cave deposits by scanning electron microscopy and thin section analysis revealed that floral pollution constitutes one of the most aggressive agents against the calcite and aragonite precipitates, being responsible for biochemical and biophysical degradation of the first order. Received: 18 December 1995 · Accepted 10 September 1996