Chemical Weathering Dynamics in River Systems

Rivers integrate chemical weathering across diverse rock types, climates and land uses, conveying dissolved solutes from catchments to the ocean. The dissolution of silicate minerals consumes atmospheric CO2 and releases bicarbonate and dissolved silica, whereas carbonate dissolution contributes to alkalinity without long‐term CO2 removal. Physical erosion continually exposes fresh mineral surfaces, linking tectonics and landscape steepness to chemical weathering rates. Biotic processes, notably soil respiration and root exudation, regulate soil CO2 concentrations and accelerate mineral breakdown. Additionally, the oxidation of rock‐bound organic carbon in mountain catchments can release substantial CO2, rivalling silicate weathering sinks. Riverine chemistry thus encapsulates a suite of CO2-driven reactions, reflecting interactions among lithology, hydrology, climate and biosphere activity. A comprehensive understanding of these dynamics underpins models of the global carbon cycle and guides predictions of how weathering fluxes will evolve under environmental change.

Research from Nature Portfolio

Recent studies have shown that oxidation of ancient rock‐bound organic carbon in rapidly eroding mountain catchments can offset or even exceed the CO2 drawdown by silicate weathering, identifying hotspots in high‐uplift regions such as the Himalayas, Andes and Rocky Mountains and emphasising a previously underappreciated geological CO2 source. Climate warming is expected to alter the generation of riverine alkalinity by up to 68 % by the end of this century, with lower emissions reducing mid-latitude bicarbonate fluxes and higher emissions enhancing them, thereby creating a sudden feedback on ocean CO2 sequestration. Global compilations of river sediment and solute data confirm that silicate weathering intensity scales primarily with temperature, as feldspar dissolution rates increase monotonically between 0 and 30 °C, supporting a strong negative feedback between surface temperature and atmospheric CO2 over geological timescales.

Chemical Weathering Dynamics in River Systems publication trend

The graph below shows the total number of articles in chemical weathering dynamics in river systems across all publications each year (not limited to Nature Index journals).

Technical terms

Silicate weathering: Reaction of silicate minerals with carbonic acid leading to mineral dissolution, bicarbonate production and net consumption of atmospheric CO2.

Carbonate weathering: Dissolution of carbonate minerals in water, releasing bicarbonate and calcium or magnesium ions and influencing riverine alkalinity without net CO2 removal over short timescales.

Petrogenic organic carbon (OCpetro): Ancient organic carbon preserved in sedimentary rocks that can be oxidised during weathering, releasing CO2.

Alkalinity: The capacity of water to neutralise acid, primarily determined by bicarbonate and carbonate ion concentrations derived from mineral dissolution.

Rhenium tracer: Use of dissolved rhenium concentrations to quantify the oxidation flux of rock‐bound organic carbon in river systems.

References

1. Rock organic carbon oxidation CO2 release offsets silicate weathering sink. Nature (2023).
2. Alkalinity responses to climate warming destabilise the Earth’s thermostat. Nature Communications (2023).
3. High rates of rock organic carbon oxidation sustained as Andean sediment transits the Amazon foreland-floodplain. Proceedings of the National Academy of Sciences of the United States of America (2023).
4. Temperature dependence of basalt weathering. Earth and Planetary Science Letters (2016).
5. Silicate versus carbonate weathering in Iceland: New insights from Ca isotopes. Earth and Planetary Science Letters (2015).
6. A global temperature control of silicate weathering intensity. Nature Communications (2022).