Regional and temporal (1992-2004) evolution of air-borne sulphur isotope composition in Saxony, southeastern Germany, central Europe

The isotopic composition of air-borne sulphur was investigated in Saxony, Southeast Germany--a region with formerly very high atmospheric SO(2) concentrations. In addition, data from various authors were compiled for different Saxonian locations, spanning from 1992 to 2004, i.e., a time of decreasing SO(2) concentrations in the atmosphere. There were no obvious temporal changes in the mean delta(34)S value of bulk precipitation. However, the variability of monthly mean delta(34)S values decreased. The mean sulphur isotope composition of sulphate from bulk precipitation after the year 2000 converges in Saxony towards 4-5 per thousand, with similar values for different locations. Mean values of different forms of sulphur show the following enrichment order: delta(34)S of SO(2) < delta(34)S of weathering crusts < or =delta(34)S of sulphate from bulk precipitation < or =delta(34)S of dust. Judging from local differences on sulphate crusts and corresponding isotope values of sources, the delta(34)S value of SO(2) as well as for crusts mainly reflects local point sources. The mean delta(34)S value of bulk precipitation represents more regionally well-mixed SO(2) sources and is therefore an ideal tool for monitoring regional atmospheric change.