Pierson-Wickmann,A.-C., Aquilina,L., Martin,C., Ruiz,L., Molenat（eの頭に´）,J., Jaffrezic（eの頭に´）,A. and Gascuel-Odoux,C.(2009): High chemical weathering rates in first-order granitic catchments induced by agricultural stress. Chemical Geology, 265, 369-380.

『農業のストレスによって誘引された一次花崗岩質流水域における高い化学風化速度』

『Abstract
　 Chemical erosion rates have been determined on two upland granitic catchments under agricultural pressure in Brittany, France. Intensive agriculture has been carried out for at least 30 years in this region. The influence of geochemical processes related to agriculture on the chemistry of streamwaters is determined through a geochemical mass balance. The elemental export fluxes from these two agricultural catchments are then compared with other catchments around the world.
　The volume and concentrations of the precipitation are taken into account, as well as the inputs of organic and chemical fertilizers, groundwaters and streamwaters, to estimate the relative influence on export fluxes, and then evaluate the elemental fluxes released by weathering. The relatively high Si flux of about 1.8± 0.9 kmol ha-1 yr-1 is directly attributed to the chemical weathering of soil and rock in the catchment system. However, the Si flux remains comparable to values found in both small and large-sized catchments under temperate and tropical conditions. On the other hand, extremely high fluxes of major cations (Ca, Na and Mg) are observed, ranging from 4.2±2.6 to 8.0±4.9 kmol ha-1 yr-1, which can be attributed to chemical weathering. These fluxes remain dramatically higher than those found in granitic catchments worldwide.
　Despite an integrated agriculture, the soil acidification induced by fertilizer application leads mainly to a release of major cations from the system, by processes of soil ion-exchange leaching as well as weathering of soil and rock.

Keywords: Chemical erosion; Granitic catchment; Agricultural inputs; Cation release; Soil acidification

1. Introduction
2. Study site description
3. Material and methods
　3.1. Water sampling
　3.2. Chemical analyses
4. Chemical budget computation
　4.1. Water mass balance
　4.2. Chemical budget computation
　　4.2.1. Precipitation budgets
　　4.2.2. Agricultural inputs
　　4.2.3. Biomass and water storage
　　4.2.4. Solute outputs
　　4.2.5. Chemical budgets
　4.3. Uncertainties
　　4.3.1. Dry deposition
　　4.3.2. Biomass uptake and mineralization
　　4.3.3. Storm events
5. Results
　5.1. Water chemistry
　　5.1.1. Precipitation (F(i)p)
　　5.1.2. Stream- and ground-waters
　5.2. Agricultural inputs (F(i)ARG)
　5.3. Stream solute fluxes and chemical erosion (F(i)SO and N(i))
6. Discussion
　6.1. Cation release and acidification processes
　6.2. Comparison of H\Kerrien and Kerbernez catchments
　6.3. Source of exported cations
　6.4. Chemical fluxes and chemical erosion rates
7. Summary and conclusions
Acknowledgments
Appendix A
Appendix B
Appendix C
References

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