Fischer & Gaupp(2005)による〔『Change of black shale organic material surface area during oxidative weathering: Implications for rock-water surface evolution』(1213p)から〕

『酸化による風化での黒色頁岩有機物表面積の変化:岩石-水表面の発達との関係』


Abstract
 Black shale oxidative weathering plays a significant role in a variety of processes including acid mine drainage and atmospheric CO2 control. The modeling of weathering is highly dependent o reactive surface area. In this study it is shown that black shale oxidative weathering is regulated mainly by the external, geometrical surface area of rock polyhedrons and the organic matter's (OM) internal surface area. The internal rock surface area decreases dramatically during OM dissolution from 〜15 m2/g to 〜5 m2/g. A linear relationship was found between the decrease of internal rock surface area and quantity of OM dissolved. Optical roughness analyses of black and bleached shale surface area reveal the formation of macropores due to the dissolution of mesoporous and probably microporous OM. However, due to deconsolidation, the geometrical external rock polyhedron surface area increases during weathering. Black shale polyhedrons show a doubling of their external surface area as OM decreases. This provokes an increase of the shale volume which is easily accessible by fluids. The increase of the external rock surface area seems to be self-accelerating during weathering. The upscaling of external and internal rock surface area evolution during weathering presented in this study demonstrates the possible application of these results to the improved understanding of a chemical transport in a variety of natural systems.』

1. Introduction
 1.1. Dissolution processes and the surface area quantification of minerals and rocks
 1.2. Surface area of rocks
 1.3. Surface area evolution during weathering
2. Geological setting
3. Materials and methods
 3.1. Petrographic observations
 3.2. Black shale weathering succession and sample selection
 3.3. Systematic method for surface area quantification
  3.3.1. External surface area quantification
  3.3.2. Internal surface area
4. Results ad discussion
 4.1. Organic carbon content
 4.2. External rock surface area
 4.3. Internal rock surface area
 4.4. Fluid-rock interfacial surface area evolution during black shale weathering−Implications for reactive surface area
 4.5. Generalizations
5. Conclusions
Acknowledgments
References
Appendix


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