Modelled glacial and non-glacial HCO3-, Si and Ge fluxes since the LGM: little potential for impact on atmospheric CO2 concentrations and a potential proxy of continental chemical erosion, the marine Ge:Si ratio

The runoff and riverine fluxes of HCO3-, Si and Ge that arise from chemical erosion in non-glaciated terrain are modelled at 6 time steps from the Last Glacial Maximum (LGM) to the present day. The fluxes that arise from the Great Ice Sheets are also modelled. Terrestrial HCO3- fluxes decrease during deglaciation, largely because of the reduction in the area of the continental shelves as sea level rises. The HCO3- fluxes, and the inferred consumption of atmospheric CO2 are used as inputs to a carbon cycle model that estimates their impact on atmospheric CO2 concentrations (atmsCO2). A maximum perturbation of atmsCO2 by ~5.5 ppm is calculated. The impact of solutes from glaciated terrain is small in comparison to those from non-glaciated terrain. Little variation in terrestrial Si and Ge fluxes is calculated (<10%). However, the global average riverine Ge:Si ratio may be significantly perturbed if the glacial Ge:Si ratio is high. At present, variations in terrestrial chemical erosion appear to have only a reduced impact on atmsCO2, and only little influence on the global Si and Ge cycle and marine Ge:Si ratios during deglaciation.