Sulfur isotopic fractionation and source appointment of PM2.5 in Nanjing region around the second session of the Youth Olympic Games

Chemical Characterization of PM2.5 at Rural and Urban Sites around the Metropolitan Area of Huancayo (Central Andes of Peru)

“…For instance, Dai et al [61] showed direct evidence of sulfate emission from residential coal combustion present in particulate matter from Xian, China. Guo et al [62] stated that one of the major sources of atmospheric sulfate is attributed to vehicle exhaust. Anthropogenic sulfate from fossil fuel combustion can be included in primary and secondary sulfate.…”

Stable Sulfur Isotopes Revealed a Major Role of Transition-Metal Ion-Catalyzed SO2 Oxidation in Haze Episodes

“…Stable sulfur isotopes (δ 34 S) have the potential to indicate the formation pathways of sulfate aerosols. The fractionation factors for sulfur isotopes during multiple oxidation pathways (SO 2 + OH, SO 2 + H 2 O 2 /O 3 , and TMI) have been determined experimentally. − Yet, to date, there are few studies using sulfate δ 34 S values to interpret the oxidation pathways of SO 2 . ,, This is because the δ 34 S values of sulfate aerosols (δ 34 S sulfate ) are simultaneously controlled by the δ 34 S values of SO 2 sources , (δ 34 S emission ) and the kinetic and equilibrium isotope effects occurring during the oxidation process. The δ 34 S emission values strongly depend on the origin of SO 2 and can, therefore, be difficult to constrain.…”

“…This isotopic fractionation during SO 2 oxidation should be treated as a Rayleigh distillation process since isotopic exchange between the product sulfate and the reactant SO 2 is minimal . Currently, many studies have measured δ 34 S sulfate in Chinese megacities ,,− to understand the sources of atmospheric SO 2 and the secondary sulfate aerosols. Some works also have measured δ 33 S and δ 36 S − to further constrain the origins of atmospheric SO 2 .…”

Roles of Sulfur Oxidation Pathways in the Variability in Stable Sulfur Isotopic Composition of Sulfate Aerosols at an Urban Site in Beijing, China

“…Investigation of formation mechanisms in atmospheric sulfate aerosols gives us a hint to better understand the sulfate budget, linked to climate changes on regional and/or global scales. Oxygen isotopic compositions, such as δ 18 O and Δ 17 O, are frequently used to identify the mechanisms of formation of sulfate aerosols, − whereas δ 34 S was considered to be attributed to the different SO 2 emission sources. , For example, the δ 34 S value of DMS was in the range of +15–19‰, − while most anthropogenic sulfate displayed much lower δ 34 S values such as that from coal combustion (+6.6 ± 3‰) and traffic emissions (+5.8 ± 3.0‰). − Obviously, the different emission sources result in the different δ 34 S values in sulfate aerosols. − Nevertheless, several recent studies used δ 34 S values to quantify the relative contributions of the different oxidation pathways from SO 2 to sulfate. ,, In the conversion of SO 2 and SO 4 2– , the isotope fractionation effects would be produced through different oxidation pathways such as OH, NO 2 , H 2 O 2 , O 3 , and O 2 catalyzed by TMIs, resulting in different signatures of δ 34 S in sulfate aerosols (δ 34 S-SO 4 2– ). , Oxidation by H 2 O 2 and O 3 produced sulfate with enriched 34 S (+15.1–19.9‰) relative to the reactant SO 2 , whereas sulfate formed by TMI catalysis depleted 34 S values (−9.5 ± 3.1‰) relative to SO 2 . In general, δ 34 S in atmospheric sulfate aerosols is definitely influenced by both the oxidation pathways and the emission sources, and the influence exhibits seasonal and geographic variability.…”