Characterization of black deposits in karst caves, examples from Slovenia

摘要: Karst caves are important tourism and natural heritage destinations. Within dry cave passages otherwise notable for their rich flowstone decoration, areas with a characteristic black color can sometimes be observed on walls floors speleothems. To determine the origin of these deposits, mineralogical chemical analyses were carried out in two (Postojna Cave Crna Jama (Kocevje), Slovenia). Qualitative composition was obtained by scanning electron microscopy conjunction energy dispersive X-ray spectrometry (SEM/EDS). Organic matter deposits confirmed Walkley–Black (wet burning) loss-on-ignition (LOI, methods. Results showed that from studied could attributed to anthropogenic causes. Natural causes related Mn–Fe oxide precipitation probably dependent microorganism activity. Anthropogenic sources historic (or/and prehistoric) human activities such as visitors using torches fires, events outside forest settlement recent air pollution. Black show effect long-term environmental impact karst included guided tours along scientific explanation origin.