『Abstract
　CO2 consumption by chemical weathering is an integral part of the boundless carbon cycle, whose spatial patterns and controlling factors on continental scale are still not fully understood. A dataset of 338 river catchments throughout North America was used to empirically identify predictors of bicarbonate fluxes by chemical weathering and interpret the underlying controlling factors. Detailed analysis of major ion ratios enables distinction of the contributions of silicate and carbonate weathering and thus quantifying CO2 consumption. Extrapolation of the identified empirical model equations to North America allows the analysis of the spatial patterns of the CO2 consumption by chemical weathering.
　Runoff, lithology and land cover were identified as the major predictors of the riverine bicarbonate fluxes and the associated CO2 consumption. Other influence factors, e.g. temperature, could not be established in the models. Of the distinguished land cover classes, artificial surfaces, dominated by urban areas, increase bicarbonate fluxes most, followed by shrubs, grasslands, managed lands, and forests. The extrapolation results in an average specific bicarbonate flux of 0.3 Mmol km^-2 a^-1 by chemical weathering in North America, of which 64％ originates from atmospheric CO2, and 36％ from carbonate mineral dissolution. Chemical weathering in North America thus consumes 50 Mt atmospheric CO2-C per year. About half of that originates from 10％ of the area of North America.
　The estimated strength of individual predictors differs from previous studies. This highlights the need for a globally representative set of regionally calibrated models of CO2 consumption by chemical weathering, which apply very detailed spatial data to resolve the heterogeneity of earth surface processes.』

1. Introduction
2. Methods
　2.1. Data sources and treatment
　2.2. Estimating bicarbonate fluxes and atmosphere CO2 contribution
　　2.2.1. Bicarbonate fluxes
　　2.2.2. CO2 contribution
　　　2.2.2.1. Correction for atmospheric inputs
　　　2.2.2.2. Correction for Na from non-silicate weathering sources
　　　2.2.2.3. Correction of non-bicarbonate balanced Ca and Na
　　　2.2.2.4. Carbonate contributions to elementary fluxes from silicate lithologies
　　　2.2.2.5. Atmospheric CO2 contribution to bicarbonate flux
　2.3. Extrapolation to North America
3. Results
　3.1. Estimation of bicarbonate fluxes
　3.2. Determination of CO2 consumption
　3.3. Extrapolation to North America
4. Discussion
　4.1. Controls on bicarbonate fluxes
　　4.1.1. Runoff and lithology
　　4.1.2. Land cover
　　4.1.3. Other factors
　4.2. Atmospheric CO2 proportion on bicarbonate fluxes
　4.3. Comparison to previous CO2 consumption model
　4.4. Extrapolation to North America
5. Conclusions
Acknowledgments
Appendix A. Source rock Ca/Na ratio
Appendix B. Maps of atmospheric deposition
Appendix C. Estimates of the prediction equations used for correction of Ca-excess
References