1. Conservative transport of dissolved sulfate across the Rio Madre de Dios floodplain in Peru.
- Author
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Burt, Emily I., Bill, Markus, Conrad, Mark E., Quispe, Adan Julian Ccahuana, Christensen, John N., Hilton, Robert G., Dellinger, Mathieu, and West, A. Joshua
- Subjects
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FLOODPLAINS , *SULFIDE minerals , *SULFUR isotopes , *SEDIMENTARY rocks , *CARBONIC acid , *CARBON cycle , *PYRITES - Abstract
Mineral weathering plays a primary role in the geologic carbon cycle. Silicate weathering by carbonic acid consumes CO² and stabilizes Earth's climate system. However, when sulfuric acid drives weathering, CO² can be released to the atmosphere. Recent work has established that sulfuric acid weathering resulting from sulfide mineral oxidation is globally significant and particularly important in rapidly eroding environments. In contrast, if SO4 ²-produced by sulfide oxidation is reduced during continental transit, then CO² release may be negated. Yet, little is known about how much SO4 ²-reduction takes place in terrestrial environments. We report oxygen and sulfur stable isotope ratios of SO4 ²-in river waters and mass budget calculations, which together suggest that SO4 ²-released from pyrite oxidation in the Peruvian Andes mountains is conservatively exported across ~300 km of the Amazon floodplain. In this system, floodplain SO4 ²-reduction does not counteract the large SO4 ²-flux from Andean pyrite weathering or measurably affect the stable isotope composition of riverine SO4 ²-. These findings support the hypothesis that uplift and erosion of sedimentary rocks drive release of CO² from the rock reservoir to the atmosphere. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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