『Abstract
　The spatial and temporal changes in hydrology and pore water elemental and ⁸⁷Sr/⁸⁶Sr compositions are used to determine contemporary weathering rates in a 65- to 226-kyr-old soil chronosequence formed from granitic sediments deposited on marine terraces along coastal California. Soil moisture, tension and saturation exhibit large seasonal variations in shallow soils in response to a Mediterranean climate. These climate effects are dampened in underlying argillic horizons that progressively developed in older soils, and reached steady-state conditions in unsaturated horizons extending to depths in excess of 15 m. Hydraulic fluxes (qh), based on Cl mass balances, vary from 0.06 to 0.22 m yr^-1, resulting in fluid residence times in the terraces of 10-24 yrs.
　As expected for a coastal environment, the order of cation abundances in soil pore waters is comparable to sea water, i.e., Na＞Mg＞Ca＞K＞Sr, while the anion sequence Cl＞NO3＞HCO3＞SO4 reflects modifying effects of nutrient cycling in the grassland vegetation. Net Cl-corrected solute Na, K and Si increase with depth, denoting inputs from feldspar weathering. Solute ⁸⁷Sr/⁸⁶Sr ratios exhibit progressive mixing of sea water-dominated precipitation with inputs from less radiogenic plagioclase. While net Sr and Ca concentrations are anomalously high in shallow soils due to biological cycling, they decline with depth to low and/or negative net concentrations. Ca/Mg, Sr/Mg and ⁸⁷Sr/⁸⁶Sr solute and exchange ratios are similar in all the terraces, denoting active exchange equilibration with selectivities close to unity for both detrital smectite and secondary kaolinite. Large differences in the magnitudes of the pore waters and exchange reservoirs result in short-term buffering of the solute Ca, Sr, and Mg. Such buffering over geologic time scales can not be sustained due to declining inputs from residual plagioclase and smectite, implying periodic resetting of the exchange reservoir such as by past vegetational changes and/or climate.
　Pore waters approach thermodynamic saturation with respect to albite at depth in the younger terraces, indicating that weathering rates ultimately become transport-limited and dependent on hydrologic flux. Contemporary rates Rsolute are estimated from linear Na and Si pore weathering gradients bsolute such that
Rsoluite = qh/bsoluteβSv
where Sv is the volumetric surface area and β is the stoichiometric coefficient. Plagioclase weathering rates (0.38-2.8×10^-15 mol m^-2 s^-1) are comparable to those based on ⁸⁷Sr/⁸⁶Sr mass balances and solid-state Na and Ca gradients using analogous gradient approximations. In addition, contemporary solute gradients, under transport-limited conditions, approximate long-term solid-state gradients when normalized against the mass of protolith plagioclase and its corresponding aqueous solubility. The multi-faceted weathering analysis presented in this paper is perhaps the most comprehensive yet applied to a single field study. Within uncertainties of the methods used, present day weathering rates, based on solute characterizations, are comparable to average long-term past rates as evidenced by soil profiles.』

１. Introduction
2. Methods
3. Results
　3.1. Precipitation inputs
　3.2. Regolith hydrology
　　3.2.1. Soil moisture
　　3.2.2. Soil water tension
　3.3. Solute chemistry
　　3.3.1. Solute Cl compositions
　　3.3.2. Solute Na distributions
　　3.3.3. Solute Ca and Sr distributions
　　3.3.4. ⁸⁷Sr/⁸⁶Sr distributions
　　3.3.5. Solute Mg distributions
　　3.3.6. Solute K distributions
　　3.3.7. Solute Si distributions
　　3.3.8. Aluminum and pH distributions
　3.4. Mineral solubilities and saturation indices
　　3.4.1. Plagioclase
　　3.4.2. K-feldspar
　　3.4.3. Kaolinite
　　3.4.4. Gibbsite
　3.5. Cation exchange
　　3.5.1. Cation exchange capacities
　　3.5.2. Exchange equilibrium
4. Discussion
　4.1. Contemporary plagioclase weathering rates based on solute Na and Si gradients
　4.2. Determination of contemporary plagioclase weathering rates based on solute ⁸⁷Sr/⁸⁶Sr gradients
　4.3. Long-term elemental weathering rates based on solid-state gradients
　　4.3.1. Determining solid-state weathering gradients
　　4.3.2. Determining solid-state weathering velocities and rates
　4.4. Comparisons of contemporary and long-term weathering
　　4.4.1. Comparison of weathering gradients
　　4.4.2. Comparison of contemporary and long-term weathering rates
　4.5. Inconsistencies in base cation weathering
5. Conclusions
Acknowledgments
Appendix A
Appendix B
Appendix C
References