On 16. 7. 2022 severe forest wildfires started in the Kras area on the border between Slovenia and Italy. As it is the place of Soča frontline during the first world war there are still a lot of explosives from that time. Within ELME (Ecological Laboratory with Mobile Unit, Civil Protection of RS) dr. Jože Kotnik performed air quality measurements, including mercury, in areas where fires were most intensive.
Results showed very high values of particulate matter in the air, PM10 were up to 1000 ug/m3 and PM2.5 up to 300 ug/m3. CO2 and ozone were also elevated. Other harmful substances were not detected with available instruments.
Mercury showed very interesting values. On already burned groundout of smoke Hg concentrations are in the range of 2 - 4 ng/m3, which are values comparable to Ljubljana. In main smoke, about 200 m from fire concentrations were constantly between 10 and 20 ng/m3. Several peaks (up to 70 ng/m3) of Hg concentrations were observed a few minutes after the detonations of explosives. At places, a few km from fire, but still in dense smoke concentrations were lower but elevated (up to 10) compared to unpolluted places.
Mercury in the atmosphere originates from two sources: burned biomass which is one of the main natural sources of Hg in the atmosphere, and mercury fulminate, which was used as a detonator for explosives during WWI and II.