nationwide survey of airborne mercury in Finland

Continuous measurements of total gaseous mercury (TGM) at an urban background station in Helsinki, Finland, were performed in 2006–2007. Additionally, a one-month campaign to measure TGM continuously from a moving car was organized in 2007, when several cities and industrial areas around Finland were surveyed. In Helsinki, a one-year average of 1.54 ± 0.20 ng m–3 was measured, which is about the global average for this persistent pollutant. The highest concentrations, up to 2500 ng m–3, were measured during firing practice that took place next to the station. Seasonal and diurnal variation was studied, and trajectory maps were constructed to analyze mercury source regions. In the mobile measurement campaign, concentrations varying between 1.0 and 13.8 ng m–3 were measured. The highest concentrations (above 10 ng m–3) were recorded close to former chlor-alkali plants that used mercury in their electrolytic production process.