Optical techniques for measurements of atmospheric trace gases

Sammanfattning: Differential optical absorption spectroscopy (DOAS) and differential absorption lidar (DIAL) have been used for measurement of atmospheric trace gases. A fully automated system for atmospheric pollution monitoring of a medium-sized city has been constructed, based on the DOAS technique. Detection of ammonia and aromatic hydrocarbons in the ultraviolet spectral region has been investigated and demonstrated. The possibility of improved sensitivity in DOAS measurements of ozone in the wavelength range around 283 nm has been investigated and demonstrated. The applicability of the DIAL technique for total flux measurements of industrial emissions has been demonstrated. Comparisons with in-situ point monitors have been performed. Atomic mercury measurements have been performed in geothermic and mineralized areas in addition to industrial sites. The total flux of sulphur dioxide from Italian volcanoes has been measured by simulaneous DOAS and DIAL measurements.