| Summary: | An imbalance in pyrite weathering and burial is regarded as one of the primary mechanisms responsible for the oxygenation of the atmosphere and oceans, but key processes governing the terrestrial sulfur cycle remain nebulous. Here, we investigate components of the terrestrial sulfur cycle in a highly productive, glacier-fed catchment, and use a global mass balance model to put constraints on the riverine sulfur fluxes. Chemistry of stream water and plant debris in the Jostedal watershed, Norway suggests sulfur isotope discrimination is occurring in the porewater. Global models also corroborate additional, previously overlooked pyrite burial with a modest isotope fractionation (<20‰), similar to values reported from freshwater ecosystems. Collectively, our results support the notion that a significant amount of sulfate produced by weathering remains trapped in terrestrial environments. This terrestrial sulfur sink might have waxed and waned over geologic time in response to major biogeochemical events such as terrestrial afforestation. Funding provided by: National Science Foundation Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001 Award Number: EAR-1225162 Funding provided by: National Science Foundation Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001 Award Number: EAR-1418716 Funding provided by: Korea Polar Research Institute Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100004230 Award Number: PE20900 Funding provided by: National Research Foundation of Korea Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003725 Award Number: 2019R1C1C1005550
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