No evidence for S isotape fractionation during SO2 oxidation at a continental location

Authors

J. Kolodziej, University of Calgary
A.L. Norman, University of Calgary
Ofelia T. Rempillo, De La Salle University, Manila

College

College of Science

Document Type

Article

Source Title

Journal of Undergraduate Research in Alberta

Volume

4

First Page

26

Last Page

35

Publication Date

2014

Physical Description

9 pages

Abstract

Introduction

Sulfur isotope fractionation during SO₂ oxidation has been shown to occur in laboratory experiments [1] but this has not been observed in whole air samples [2]. Here we replicate the laboratory experiments in a systematic manner using ambient air.

Methods

Particulate matter and SO₂ in ambient air were collected at Calgary in the fall of 2012 using high volume samplers and impingers. Atmospheric SO₂ and SO­₄ concentrations and isotope characteristics were determined.

Results

Variations in concentrations did not reflect changes in δ³⁴S values, suggesting the independence of δ³⁴S from SO₂ and SO₄ concentrations in the atmosphere. d³⁴S_SO2 values for high volume samples was, on average, +13.2‰ ± 0.2‰. SO₂ from the impinger method over the same sampling period yielded a δ³⁴S_SO2 value of +14.0‰ ± 0.2‰. δ³⁴S_SO4 values ranged from +9.9‰ ± 0.5‰ to +15.3‰ ± 0.2‰.

Discussion and Conclusions

δ³⁴S_SO2 values from the high volume and impinger samples were similar (+13.2‰ versus +14.0‰, respectively) and shows d³⁴S values from these collection methods are equivalent. Differences between the impinger and high volume sampler d³⁴S values for SO₂ and submicron aerosol sulfate were used to gauge sulfur isotope fractionation. Standard deviations for differences were greater than averages (Δd³⁴S_SO2 avg.= -0.80‰, s=1.76‰; fine Δd³⁴S_SO4 avg.=+0.28‰, s=5.15‰), indicating little to no fractionation. Additionally, δ³⁴S_SO2 and δ³⁴S_SO4 values were compared to the maximum percent SO₂ that may have reacted to form SO₄. No pattern was evident so the conclusion is that sulfur isotope fractionation in ambient air is negligible under the conditions sampled.

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Recommended Citation

Kolodziej, J., Norman, A., & Rempillo, O. T. (2014). No evidence for S isotape fractionation during SO2 oxidation at a continental location. Journal of Undergraduate Research in Alberta, 4, 26-35. Retrieved from https://animorepository.dlsu.edu.ph/faculty_research/10833

Disciplines

Physical Sciences and Mathematics

Keywords

Sulfur—Isotopes; Sulfur--Oxidation

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