In 1992, a monitoring survey on a national scale was carried out using Hypogymnia physodes (L.) Nyl. as a biomonitor for trace element air pollution. The primary aim was to analyse epiphytic lichens collected at 86 sampling locations of the 16 x 16 km bioindication grid using k(0)-based instrumental neutron activation analysis (k(0)-INAA), and X-ray fluorescence spectrometry (XRF) for sulphur and lead, to obtain information about the levels of elements in the atmosphere and to identify significant pollution sources. The geographical concentration patterns of the trace elements obtained from the lichen data were mapped and compared with the index of atmospheric purity (IAP) calculated on the basis of data from lichen thalli type mapping, obtained on a more dense bioindication grid in 1991. The results obtained showed good agreement between the mapping of sulphur and trace elements with the status of lichen vegetation. The most exposed regions with elevated trace element levels and lower values of IAP were in the north-western Alpine part of Slovenia which coincides with high precipitation, and in the east of Slovenia, where many local pollution sources are situated.

Needles of 20 years old spruces from Prednji vrh, in the area affected by the Sostanj power station, and from Pokljuka (Alps region, with a relatively unpolluted environment), were analysed for total sulphur content (St). Measurements were taken in a period between April and August twice monthly and in the period from August to April every four weeks (May 1993 - June 1994). Sulphur content in one and two years old spruce needles from Prednji vrh were much higher (one year old needles 2.06-2.50 mg/g needle dry weight, 1993) than in needle samples from Pokljuka (one year old needles 1.05-1.25 mg/g needle dry weight, 1993).