Tracing the sources of sulfur in Beijing soils with stable sulfur isotopes

Abstract

Stable sulfur isotope analyses were applied in order to trace local sulfur sources and to identify sulfur turnover rates in Beijing soil. Anthropogenic sources and atmospheric deposition are the main processes responsible for the occurrence of sulfide, organic and sulfate sulfur in three soil profiles located in the vicinity of a steel company in Beijing, China. This input results in an atypical invariable sulfur isotopic composition along the vertical profiles. The δ 34S values of soil sulfate from the industrial area revealed that both the topsoil and deep soil have been affected by industrial activities. Three soil profiles from non-industrial areas displayed vertical patterns in both sulfur abundance and sulfur isotopic composition, indicative for (close to) natural soils. Eight soil profiles collected in Beijing and their vertical distribution of different sulfur species, concentrations and sulfur isotopic compositions reveal both anthropogenic and natural contributions.

How does the content of nutrients in soil affect the health status of trees in city parks?

“…There were larger amounts of this component at individual sites. There were similar amounts of sulphur in Beijing (China), where they ranged from 14.7 to 189.9 mg dm -3 at different sites [65]. The content of sulphur in the soil decreased as the depth increased.…”

Using stable isotopes to trace sources and formation processes of sulfate aerosols from Beijing, China

“…In addition, the contribution of oil combustion is relatively constant throughout the year as there is no seasonal variation in oil consumption. By solving equations (1)–(3) , , , the contributions of sulfate sources can be calculated (results listed in Table 3 ), assuming a δ 34 S oc value of 20.5 ± 4.8‰ 47 , a δ 34 S cc value of 6.6 ± 3‰ 47 48 , a δ 34 S bs value of −6 ± 4‰ 21 22 23 and a δ 34 S ts value of 4.5 ± 3.5‰ 51 52 as the respective δ 34 S signature of each sulfur source. The results show that the average contributions of coal combustion, oil combustion, biogenic sulfur and terrigenous sulfate to sulfate in aerosols of Beijing are 49.6 ± 7.5%, 17.6 ± 8.6%, 19.8 ± 9.9% and 10.1 ± 6.2%, respectively, but exhibiting strong seasonal differences ( Table 3 ).…”

“…where f oc , f cc , f bs and f ts represent the fractional contributions of oil combustion, coal combustion, biogenic source and terrigenous source, respectively, and δ 34 S oc , δ 34 S cc , δ 34 S bs and δ 34 S ts represent the corresponding δ 34 S value of each sulfur source. We assume a δ 34 S oc value of 20.5 ± 4.8‰ 47 , a δ 34 S cc value of 6.6 ± 3‰ 47 48 , a δ 34 S bs value of −6 ± 4‰ 21 22 23 and a δ 34 S ts value of 4.5 ± 3.5‰ 51 52 as the respective δ 34 S signature of each sulfur source.…”

Seasonality in the Δ<sup>33</sup>S measured in urban aerosols highlights an additional oxidation pathway for atmospheric SO<sub>2</sub>

“…Two main lines of reasoning are usually evoked to explain such S-isotope compositions. The first one neglects the role of S-isotope fractionation and uses S-isotopes as a direct tracer of emission sources that have been shown to be characterized by large and distinct δ 34 Svalues (Becker and Hirner, 1998;Calhoun et al, 1991;Gaffney et al, 1980;Guo et al, 2016;Newman and Forrest, 1991;Nielsen, 1974;Premuzic et al, 1986;Smith and Batts, 1974;Wadleigh et al, 1996;Wasiuta et al, 2015). For example, sea-salt sulfate is characterized by a δ 34 S-value of 21‰ (Rees et al, 1978), marine biogenic non-sea salt sulfate has a δ 34 S ranging from 12 to 19‰ (Calhoun et al, 1991;Sanusi et al, 2006;Oduro et al, 2012), while anthropogenic sulfur emissions are often lighter although there are significant variations between sources ranging from -40 to 30‰ (Nielsen, 1974;Wasiuta et al, 2015;Krouse and Grinenko, 1991).…”