On the relation between anthropogenic SO 2 emissions and concentration of sulfate in air and precipitation

Abstract

The relationship between anthropogenic SO 2 emissions and the concentration of sulfate in air and precipitation has been investigated by comparing variations over the years, during the year and during the week. A 50 per cent increase in sulfate concentration in Swedish precipitation between the late 1950s and the early 1970s, followed by a 20–25 per cent decrease in concentration until the early 1980s agree well with estimated changes in anthropogenic SO 2 emissions in the countries that contribute to the deposition in Sweden. A more detailed analysis of sulfate in precipitation during the period 1972–1986 shows a decrease in concentration of about 40% and in deposition of about 20%. This decrease compares reasonably well with estimates based on model calculations of long-range transport and reported reductions in emissions in northern Europe. Variation of SO 2 concentrations during the week exhibits a systematic pattern in approximate agreement with the expected variation in emission rates. A reasonable agreement also exists for sulfate concentration in air during the summer months in regions close to the major emission areas. We conclude that there seems to be a qualitative agreement between changes in anthropogenic SO 2 emissions and changes in the concentration and deposition of sulfate in northern Europe.