Global silicate weathering flux overestimated because of sediment-water cation exchange.

ABSTRACT: Rivers carry the dissolved and solid products of silicate mineral weathering, a process that removes [Formula: see text] from the atmosphere and provides a key negative climate feedback over geological timescales. Here we show that, in some river systems, a reactive exchange pool on river suspended particulate matter, bonded weakly to mineral surfaces, increases the mobile cation flux by 50%. The chemistry of both river waters and the exchange pool demonstrates exchange equilibrium, confirmed by Sr isotopes. Global silicate weathering fluxes are calculated based on riverine dissolved sodium (Na⁺) from silicate minerals. The large exchange pool supplies Na⁺ of nonsilicate origin to the dissolved load, especially in catchments with widespread marine sediments, or where

SUBMITTER: Tipper ET 

PROVIDER: S-EPMC7817223 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature