Isotopic composition of sulphates from meteoric precipitation as an indicator of pollutant origin in Wrocław (SW Poland).

This paper describes the results of isotopic analyses of (i) hydrogen and oxygen in water (delta DH2O and delta18OH2O ) and (ii) sulphur and oxygen in sulphates (delta34Ssulphate and delta18Osulphate) from atmospheric precipitation collected within a one-year period between 25 May 2004 and 25 May 2005 in Wrocław (SW Poland). The resulting equation of Local Meteoric Water Line for Wrocław is delta D=6.373xdelta18O-0.047, (r2=0.97, n=32). The delta34Ssulphate varies from 1.1 to 4.2 per thousand (with an average of 2.5 per thousand), delta18Osulphate varies from 9.0 to 16.7 per thousand (with an average of 13.8 per thousand) and delta18OH2O varies from-0.8 to-16.3 per thousand (with an average of-8.2 per thousand). The above results indicate two main sources of sulphates in Wrocław precipitation: (i) low-temperature secondary sulphates forming in situ in Wrocław from the atmospheric SO2 as well as precipitation water (heterogeneous and homogeneous pathways oxidation) and (ii) high-temperature primary sulphates forming in rapid high-temperature hydratation of SO3- in an immediate proximity of industrial chimneys. We hypothesise that the secondary low-temperature type of sulphates is probably formed from the local sulphur and oxygen reservoirs, whereas the primary high-temperature type is allochthonous and it is probably transported from industrial areas located outside of Wrocław.