DETERMINATION OF SO2, HNO3, NH3 AND AEROSOL COMPONENTS AT A HIGH ALPINE BACKGROUND SITE WITH A FILTER PACK METHOD

In the time period from November 1991 to November 1992 measurements of SO2, HNO3, NH3 and particulate SO42-, NO3- and NH4+ were conducted at the Sonnblick Observatory in the Austrian Alps. To allow continuous daily measurements a filter pack was used. The precision of the method was checked in respect to the harsh meteorological conditions at the high alpine site and showed acceptable coefficients of variance (< 20%) for particulate matter and nitric acid and slightly higher variations for the gases ammonia (25%) and sulphur dioxide (30%). The annual variations showed large seasonal differences for the aerosol components and for the gases nitric acid and ammonia. Maximum summer/winter ratios were 8, 11 and 17 for the aerosol species NO3- SO42- and NH4+ respectively and 5 for HNO3 and NH3, No marked summer/winter differences could be determined for sulphur dioxide. During winter the absolute concentrations at Mt. Sonnblick were comparable with results reported for measurements of free tropospheric air. In summer a wide scatter of concentrations was determined ranging up to values typically for the planetary boundary layer in remote regions.