Assessing pyrite-derived sulfate in the Mississippi River with four years of sulfur and triple-oxygen isotope data

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1021/acs.est.7b05792. This is version 1 of this Preprint.

Downloads

Download Preprint

Supplementary Files
Authors

Bryan Killingsworth, Huiming Bao , Issaku Kohl

Abstract

Riverine dissolved sulfate (SO42−) sulfur and oxygen isotope variations reflect their controls such as SO42− reduction and re-oxidation, and source mixing. However, unconstrained temporal variability of riverine SO42− isotope compositions due to short sampling durations may lead to mischaracterization of SO42− sources, particularly for the pyrite-derived sulfate load. We measured the sulfur and triple-oxygen isotopes (δ34S, δ18O, and ∆’17O) of Mississippi River SO42− with biweekly sampling between 2009-2013 to test isotopic variability and constrain sources. Sulfate δ34S and δ18O ranged from −6.3‰ to −0.2‰ and −3.6‰ to +8.8‰, respectively. Our sampling period captured the most severe flooding and drought in the Mississippi River basin since 1927 and 1956, respectively, and a first year of sampling that was unrepresentative of long-term average SO42−. The δ34SSO4 data indicate pyrite-derived SO42− sources are 74 ±10% of the Mississippi River sulfate budget. Furthermore, pyrite oxidation is implicated as the dominant process supplying SO42− to the Mississippi River, whereas the ∆’17OSO4 data shows 18 ±9% of oxygen in this sulfate is sourced from air O2.

DOI

https://doi.org/10.31223/X50P7Z

Subjects

Geochemistry

Keywords

sulfide oxidation, sulfur isotopes, sulfate, triple oxygen isotopes, mine drainage

Dates

Published: 2021-09-02 19:52

Last Updated: 2021-09-03 02:52

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
The data associated with this work is made available by the publisher at https://doi.org/10.1021/acs.est.7b05792 in the supporting information.

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.