Sulfur isotopic composition and source identification of atmospheric environment in central Zhejiang, China

Abstract

Sulfur dioxide and sulfate aerosols in the atmosphere are significant factors leading to acidification of the atmospheric environment and worsening the pollution of acid deposition. Because of the "fingerprint" characteristics of the stable sulfur isotopic composition, sulfur isotope has been widely adopted in environmental researches concerning sulfur cycle and source identification. In this study, the atmospheric environment of Jinhua City, central Zhejiang Province, was continuously monitored, and the sulfur isotopic composition of SO 2 and sulfate aerosols in the atmosphere was analyzed. The results indicate that the variation of δ 34 S values for SO 2 ranges from 1.0‰ to 7.5‰, and annual average is 4.7‰±2.3‰, whereas that of sulfate aerosols ranges from 6.4‰ to 9.8‰，and annual average is 8.1‰±1.0‰. The δ 34 S values for SO 2 have significant seasonal variations, which are 7.0‰ in winter and 3.3‰ in summer. These variations cannot be attributed to a single factor, and we suggest a temperature-dependent isotope equilibrium fractionation and elevated biogenic sulfur emissions of isotopically light S in summer may be the main controlling mechanisms. Furthermore, we also discuss the δ 34 S model of atmospheric SO 2 oxidation to form sulfate, and suggest that heterogeneous oxidation dominates in the oxidation reactions of atmospheric SO 2 in the central Zhejiang Province. We further suggest that the relative humidity in the atmosphere plays an important role in the oxidation mechanism of atmospheric SO 2 . sulfur isotope, SO 2, aerosol, homogeneous oxidation, heterogeneous oxidation Citation:Zhang M Y, Wang S J, Ma G Q, et al. Sulfur isotopic composition and source identification of atmospheric environment in central Zhejiang, China.

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

“…Previously, the negative correlation between δ 34 S-SO 4 2− and SOR was also found in Nanjing, China, during a haze episode, indicating that SO 2 oxidation would change δ 34 S-SO 4 2− values. 43 Zhang et al 44 suggested a high RH enlarged the surfaces of droplets and wet aerosols in the atmosphere, which resulted in the aqueous-phase oxidation reactions of atmospheric SO 2 with oxidants. In addition, the significant correlation between δ 34 S and RH might suggest that isotope fractionation occurred in aqueous-phase oxidation of SO 2 to sulfate formation.…”

Regional characteristics of atmospheric δ34S-SO42− over three parts of Asia monitored by quartz wool-based passive samplers

“…In this study, the range of δ 34 S-SO 4 2− in North China was 0.8-7.5‰, with the tendency corresponding well to the values of source coals (6.6‰) (Maruyama et al, 2000;Yetang et al, 1993). Sulfur isotopic composition varied greatly in southern coal due to regional differences, for example, the δ 34 S coal ranges in the Pearl River Delta, Southeast China, and Southwest China were 3.1-6.7‰ (Liu et al, 1996;Xiao et al, 2015;Zhang et al, 1995;Zhang et al, 2010), −0.7-10.2‰ (Chameides and Stelson, 1992;Zhang et al, 1995;Zhang et al, 2010), and − 1.7-5.4‰ (Yetang et al, 1993;Zhang et al, 2002;Zhang et al, 2010), respectively. The ranges of δ 34 S-SO 4 2− in the Pearl River Delta, Southeast China, and Southwest China was 3.5-4.4‰, 0.2-2.9‰, and 4.8-5.7‰, respectively, which were close to the δ 34 S coal values at the sites.…”

Anthropogenic Emission Sources of Sulfate Aerosols in Hangzhou, East China: Insights from Isotope Techniques with Consideration of Fractionation Effects between Gas-to-Particle Transformations

“…Some field studies synchronously measured the δ 34 S values in ambient SO 2 and SO 4 2– samples. ,, They found significant differences (>2‰) of δ 34 S values between SO 2 and particulate SO 4 2– in central and northern China, providing evidence to support the fractionation effects of δ 34 S through the transformation of SO 2 into SO 4 2– . The significant fractionation effects were responsible for the apparent seasonality of δ 34 S-SO 4 2– in the atmosphere .…”

“…In general, the fractionation factors of δ 34 S (α 34 S g→p ) through SO 2 oxidation were temperature-dependent, except for that of the SO 2 + NO 2 oxidation pathway. , Compared to SO 2 oxidation by OH, H 2 O 2 /O 3 , and NO 2 , only transition-metal-ion (TMI) catalytic oxidation of SO 2 possessed the negative fractionation factors . Previous many studies have suggested that α 34 S g→p values should be considered in quantification of emission sources to sulfate when the fractionation effects of δ 34 S were significant; otherwise, the estimated source apportionments to sulfate might be more uncertain. ,, In spite of this, none of the previous studies have considered the fractionation effects of δ 34 S when apportioning the emission sources of sulfate by sulfur isotope compositions. , …”