Abstract Drenov Grič black limestone is considered to be one of the most beautiful Slovenian natural stones due to its black colour interwoven with white veins. Over the centuries, it has been extracted from two major quarries located west of Ljubljana. One of these quarries has been declared a valuable natural feature of national importance and is protected as a natural monument. This well-stratified, Triassic (Carnian) micritic limestone occurs in 10–80 cm thick beds with thin marl interlayers. The limestone occasionally contains abundant fossil bivalves, gastropods and ostracods. It is relatively rich in carbonaceous and bituminous organic matter, which is responsible for the black colour of the stone. The stone has been widely used in Slovenian monuments. Many indoor and outdoor architectural elements have been constructed using this limestone, particularly during the Baroque period, which was known for its extensive use of black limestones in other European countries as well. The most significant use of this limestone has been recorded in sculpted portals and altars. Some important buildings, which were decorated utilizing this stone, have been declared cultural monuments of local or national importance. Use of this limestone was also documented in other European countries (Italy, Austria, Serbia) and worldwide (USA). When exposed to climatic influences, chromatic and salt weathering are recognized as the main deterioration phenomena for this limestone when used in monuments.

Abstract The Škocjan Caves are included in UNESCO’s World Heritage List due to their outstanding natural features. The caves include a large underground canyon containing the Reka River, collapse dolines with vegetation in rock fissures and impressive archaeological sites with a rich history of speleological and scientific research. They are also included in the Ramsar Directory of Wetlands of International Importance. Together with their broader surface area, the site is known as the UNESCO Karst Biosphere Reserve. The aim of the management of the reserve is to protect the World Heritage Site and to preserve its outstanding universal value for future generations. The protection activities are regulated by the provisions of international documents, the Škocjan Caves Regional Park Act and the park’s management plan. These activities include monitoring of the water quality in the Reka River and meteorological surveys on the surface. Monitoring of the microclimate of the caves focuses on measuring the effects of tourism and monitoring the levels of radon, with the aim of the ensuring the safety of the park’s employees. Ensuring a favourable status for the underground habitats and species is laid down in the Natura 2000 management programme. Particular attention is paid to ensuring high-quality, safe visits to the caves and providing educational and awareness-raising activities on the surface of the park.

Abstract Year-long continuous radon monitoring was carried out (using Sarad Radon Scout devices) in a dwelling with high radon levels in the karst region of Slovenia. Two living rooms were selected: one on the ground floor with normal housework activities; and the second, on the first floor, closed and unattended. Meteorological data were also recorded. The following seasonal geometric means of radon activity concentration (kBq m −3 ) have been found: 6.28 ×/: 3.05 for spring, 1.25 ×/: 3.78 for summer, 5.17 ×/: 2.03 kBq m −3 for autumn and 9.83 ×/: 1.48 for winter on the ground floor; and 1.43 ×/: 3.71 for spring, 0.168 ×/: 2.49 for summer, 1.08 ×/: 2.39 for autumn and 2.08 ×/: 2.14 for winter on the first floor. Results are supported by additional radon measurements in other rooms; and in water the results indicate a strong radon source associated with an underground karst shaft.