부산대학교 도서관

An imbalance in pyrite weathering and burial is a primary mechanism responsible for 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 constrain 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 indicate 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. Plain Language Summary: The amount of oxygen in Earth's surface environments is governed by the balance between formation of sulfur‐bearing pyrite and its exposure to the atmosphere and consequent destruction (rusting). Pyrite commonly forms during bacterial activity in oxygen‐free conditions, for example, in bogs, soil, and sediment. Here, we study the destruction and formation of pyrite by examining the chemistry of stream water, meltwater of snow and glacial ice, rain water, sediment, rock, soil, and plants within a glacial meltwater stream environment. Sulfur isotope compositions indicate that a large amount of pyrite forms by bacterial activity in this river system. Modeling of the global sulfur budget also supports our findings that, on the global scale, a significant amount of pyrite has formed in such systems throughout Earth's history, affecting the balance between formation and destruction of pyrite, thus playing a key role in climate and environmental changes. Key Points: Glacier‐driven weathering (both pyrite and silicate) and sulfur cycle were examined in a meltwater systemδ34S of the natural reservoirs indicates microbial sulfate reduction and burial of reduced sulfur occurring in the watershedResults of global sulfur cycle model confirm a significant flux of terrestrial sulfur burial driven by microbial reduction [ABSTRACT FROM AUTHOR]