『Abstract
　The isotope ratio of the meteoric cosmogenic nuclide ¹⁰Be to the mineral-derived stable isotope ⁹Be discloses both the Earth surface denudation rate and its weathering intensity. We develop a set of steady state mass balance equations that describes this system from a soil column over the hillslope scale to an entire river basin. The prerequisites making this new approach possible are: (1) the ⁹Be concentration of parent rock (typically 2.5±0.5 ppm in granitic and clastic sedimentary lithologies) is known; (2) both Be isotopes equilibrate between the fluids decomposing rock and reactive solids formed during weathering; and (3) a critical spatial scale is exceeded at which the fluxes of both isotopes into and out of the weathering zone are at steady state over the time scale of weathering (typically 〜10 kyr). For these cases the isotope ratios can be determined in bulk sediment or soil, on leachates from the reactive (adsorbed and pedogenic mineral-bound) phase in sediment or soil, and even on the dissolved phase in river water. The ¹⁰Be/⁹Be ratio offers substantial advantages over the single-isotope system of meteoric ¹⁰Be.The latter system allows to directly determine erosion rates only in the case that ¹⁰Be is fully retentive in the weathering zone and that riverine sorting has not introduced grain size-dependent ¹⁰Be concentration gradients in sediments. We show the feasibility of the ¹⁰Be/⁹Be tracer approach at the river scale for sediment and water samples in the Amazon basin, where independent estimates of denudation rates from in situ-produced ¹⁰Be exist. We furthermore calculate meaningful denudation rates from a set of published ¹⁰Be/⁹Be ratios measured in the dissolved load of globally distributed rivers. We conclude that this isotope ratio can be used to reconstruct global paleo-denudation from sedimentary records.

Keywords: Earth surface processes; cosmogenic nuclides; critical zone; river weathering and erosion fluxes; Amazon river』

1. Introduction
2. A conceptual framework for the ¹⁰Be/⁹Be system at the Earth surface
　2.1. ¹⁰Be and ⁹Be mass balance during steady-state weathering
3. Assumptions and requirements
4. ¹⁰Be/⁹Be ratios in the Amazon and Orinoco basins
　4.1. Hydrochemical characteristics and sediment fluxes
　4.2. Grain size dependence
　4.3. Equilibrium between (¹⁰Be/⁹Be)reac and (¹⁰Be/⁹Be)diss
　4.4. Amazon basin denudation rates
5. Denudation rates from ¹⁰Be/⁹Be in large rivers
6. Discussion and conclusions
Acknowledgements
Appendix A.1. Quantifying the bias on E introduced by loss of ¹⁰Be to solution
Appendix A.2. Quantifying the bias on D from (¹⁰Be/⁹Be)reac introduced by ignoring the Q/Kd term in Eqs. (12) and (13)
Appendix A. Supporting information
References