Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion

doi:10.1016/j.geomorph.2016.09.040

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	Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion
	Slavik, Martin 2; Bruthans, Jiri 2; Filippi, Michal 1; Schweigstillova, Jana 3; Falteisek, Lukas 2; Rihosek, Jaroslav 2
刊名	GEOMORPHOLOGY
	2017
卷号	278 页码:298-313
关键词	Biofilm Biocrust Biologically-initiated rock crust Sandstone protection Case hardening
ISSN号	0169-555X
DOI	10.1016/j.geomorph.2016.09.040
英文摘要	Biocolonization on sandstone surfaces is known to play an important role in rock disintegration, yet it sometimes also aids in the protection of the underlying materials from rapid erosion. There have been few studies comparing the mechanical and/or hydraulic properties of the BIRC (Biologically-Initiated Rock Crust) with its subsurface. As a result, the overall effects of the BIRC are not yet well understood. The objective of the present study was to briefly characterize the BIRC from both the mineralogical and biological points of view, and especially to quantify the effect of the BIRC upon the mechanical and hydraulic properties of friable sandstone. The mineralogical investigation of a well-developed BIRC showed that its surface is enriched in kaolinite and clay-to silt-sized quartz particles. Total organic carbon increases with the age of the BIRC. Based on DNA sequencing and microscopy, the BIRC is formed by various fungi, including components of lichens and green algae. Using the method of drilling resistance, by measuring tensile strength, and based on water jet testing, it was determined that a BIRC is up to 12 times less erodible and has 3-35 times higher tensile strength than the subsurface friable sandstone. Saturated hydraulic conductivity of the studied BIRC is 15-300 times lower than the subsurface, and was measured to also decrease in capillary water absorption (2-33 times). Water-vapor diffusion is not significantly influenced by the presence of the BIRC The BIRC thus forms a hardened surface which protects the underlying material from rain and flowing water erosion, and considerably modifies the sandstone's hydraulic properties. Exposing the material to calcination (550 degrees C), and experiments with the enzyme zymolyase indicated that a major contribution to the surface hardening is provided by organic matter. In firmer sandstones, the BIRC may still considerably decrease the rate of weathering, as it is capable of providing cohesion to strongly weathered (and disintegrated) sandstone surfaces. However, only a near-surface zone of the sandstone is stabilized by the BIRC, and additional sources of stabilization (gravity-induced stress, inorganic cement, etc.) contribute to the resistance of the subsurface zone of sandstone exposures. (C) 2016 Elsevier B.V. All rights reserved.
WOS研究方向	Physical Geography ; Geology
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000392555000022
内容类型	期刊论文
源URL	[http://119.78.100.198/handle/2S6PX9GI/4005]
专题	岩土力学所知识全产出_期刊论文
作者单位	1.CAS, Inst Geol; 2.Charles Univ Prague, Fac Sci; 3.CAS, Inst Rock Struct & Mech
推荐引用方式 GB/T 7714	Slavik, Martin,Bruthans, Jiri,Filippi, Michal,et al. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion[J]. GEOMORPHOLOGY,2017,278:298-313.
APA	Slavik, Martin,Bruthans, Jiri,Filippi, Michal,Schweigstillova, Jana,Falteisek, Lukas,&Rihosek, Jaroslav.(2017).Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion.GEOMORPHOLOGY,278,298-313.
MLA	Slavik, Martin,et al."Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion".GEOMORPHOLOGY 278(2017):298-313.