Soil, regolith, and weathered rock: Theoretical concepts and evolution in old-growth temperate forests, Central Europe

Šamonil, Pavel; Phillips, Jonathan D.; Daněk, Pavel; Beneš, Vojtěch; Pawlik, Łukasz

doi:10.1016/j.geoderma.2020.114261

Cited by 16 publications

(7 citation statements)

References 57 publications

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“…In several studies, GPR has allowed us to accurately delineate interfaces of several relevant structures in the critical zone (e.g. Carrière et al, 2013;Hare et al, 2017;Guo et al, 2019;Šamonil et al, 2020). However, as GPR requires sliding of the instrument on the ground, its use is much more ticklish and time-consuming over long distances in forests than in open areas, such as grassland or cropland.…”

Section: From the Weierbach Catchment Perspective And Beyondmentioning

confidence: 99%

“…Specifically, the regolith of the Weierbach catchment is representative of the slate regolith which covers a large part of the Rhenish Massif (Moragues-Quiroga et al, 2017). Hence, we anticipate that the proposed protocol could be used in several regions of this large central European geological area that extends from Luxembourg through Belgium, France and Germany (Sauer and Felix-Henningsen, 2006).…”

Section: From the Weierbach Catchment Perspective And Beyondmentioning

confidence: 99%

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Exploring the regolith with electrical resistivity tomography in large-scale surveys: electrode spacing-related issues and possibility

Laurent

Clément²,

Juilleret

et al. 2021

Hydrol. Earth Syst. Sci.

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Abstract. Within the critical zone, regolith plays a key role in the fundamental hydrological functions of water collection, storage, mixing and release. Electrical resistivity tomography (ERT) is recognized as a remarkable tool for characterizing the geometry and properties of the regolith, overcoming limitations inherent to conventional borehole-based investigations. For exploring shallow layers, a small electrode spacing (ES) will provide a denser set of apparent resistivity measurements of the subsurface. As this option is cumbersome and time-consuming, larger ES – albeit offering poorer shallow apparent resistivity data – is often preferred for large horizontal ERT surveys. To investigate the negative trade-off between larger ES and reduced accuracy of the inverted ERT images for shallow layers, we use a set of synthetic “conductive–resistive–conductive” three-layered soil–saprock/saprolite–bedrock models in combination with a reference field dataset. Our results suggest that an increase in ES causes a deterioration of the accuracy of the inverted ERT images in terms of both resistivity distribution and interface delineation and, most importantly, that this degradation increases sharply when the ES exceeds the thickness of the top subsurface layer. This finding, which is obvious for the characterization of shallow layers, is also relevant even when solely aiming for the characterization of deeper layers. We show that an oversized ES leads to overestimations of depth to bedrock and that this overestimation is even more important for subsurface structures with high resistivity contrast. To overcome this limitation, we propose adding interpolated levels of surficial apparent resistivity relying on a limited number of ERT profiles with a smaller ES. We demonstrate that our protocol significantly improves the accuracy of ERT profiles when using large ES, provided that the top layer has a rather constant thickness and resistivity. For the specific case of large-scale ERT surveys the proposed upgrading procedure is cost-effective in comparison to protocols based on small ES.

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Section: From the Weierbach Catchment Perspective And Beyondmentioning

confidence: 99%

Section: From the Weierbach Catchment Perspective And Beyondmentioning

confidence: 99%

Exploring the regolith with electrical resistivity tomography in large-scale surveys: electrode spacing-related issues and possibility

Laurent

Clément²,

Juilleret

et al. 2021

Hydrol. Earth Syst. Sci.

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“…From these studies on agricultural , and forested land, NO 3 – -N has been observed to decrease exponentially with depth, with shallow soil layers storing a large amount of NO 3 – -N. Much more NO 3 – -N could possibly exist deeper in the soil (>100 cm), presenting a threat of a nitrate time bomb that has been neglected . Deep soil extends from the subsurface (100 cm) to the bedrock surface, which in the red soil CZ includes regolith (soil and saprolite) and weathered bedrock . In a recent study, Wu et al reported that NO 3 – -N accumulated in deep soil (827 ± 97 kg N ha –1 ) was about 12 times that in shallow soil layers in a red soil CZ.…”

Section: Introductionmentioning

confidence: 99%

Deep Nitrate Accumulation in a Highly Weathered Subtropical Critical Zone Depends on the Regolith Structure and Planting Year

Yang

Dong

et al. 2020

Environ. Sci. Technol.

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Nitrate accumulated deep (>100 cm) in the regolith (soil and saprolite) threatens groundwater quality, but most studies focus only on nitrate nearer the surface (<100 cm). Surface soil management versus regolith interactions affect deep nitrate leaching, but their combined impact remains unclear. This study measured how deep nitrate accumulation was affected by crop practices including orchard/cropland planting years, regolith structure, and soil properties in highly weathered subtropical red soils. Deep nitrate storage varied from 43.6 to 1116.3 kg ha–1. Regolith thickness was positively correlated with nitrate storage (R 2 = 0.43, p < 0.05). Reticulated red clay (110–838 cm) had 81% of the accumulated nitrate and overlapped with 79% of the nitrate accumulation layer. All of the nitrate accumulation parameters (except for peak depth (PD)) generally increased with the planting years. The difference in peak nitrate concentration (9.0–20.0 mg kg–1) with planting year gradient (3–58 years) varied by 2.2 times, and the difference in nitrate storage (43.6–425.7 kg ha–1) varied by 9.8 times. Texture and pH explain 41.6% of the variation in nitrate concentration. As soil management practices interact with deeper regolith to control the spatial pattern of nitrate accumulation, vulnerable regions could be identified to avoid high accumulation.

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“…Therefore, geochemical differences in volcanic rocks compositions (mostly silica content) and geomorphological constraints potentially controlled by differential tectonics have resulted together in differentiation of chemical erosion and bauxitic weathering in highland western Cameroon (see also Samonil et al, 2020). The current bauxitic plateaus stand as long-lived elevated but differentially incised landforms (Figs.…”

Section: Optimal Drainage Upon Weathering Front Was Instrumental For mentioning

confidence: 98%

Differentiated Neogene bauxitization of volcanic rocks (western Cameroon): Morpho-geological constraints on chemical erosion

Momo

Beauvais

Tixier

et al. 2020

CATENA

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Lateritic weathering of Miocene volcanic rocks from western Cameroon highlands formed duricrusted bauxitic profiles. Two weathering profiles on ca. Ma basalt and ca. 16 Ma trachyte were studied using geochemical mass balance functions. Less mobile elements Ti and Zr were used as references to quantify volumetric change (strain, ε), element transfer rate (τ) and geochemical mass transfers during the bauxitization process of basalt and trachyte. Conversion of parent rocks to kaolinite and goethite rich saprolites evolved to Al-Fe rich bauxites, mostly composed of gibbsite and iron oxy-hydroxides (goethite and hematite). However, formation of Al-Fe bauxitic profiles required higher Si leaching on trachyte than on basalt. Our results document that chemical weathering of a larger thickness of trachyte than basalt has been required to form a unit meter of weathering profile, implying differential rates of rock chemical erosion and topographic decay of landscapes. Rates of chemical erosion and formation of lateritic weathering profiles in western Cameroon have been mostly controlled by drainage conditions and volcanic rocks composition (mostly SiO 2 content differences), that also resulted in contrasted landscapes evolution during the Neogene.

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Soil, regolith, and weathered rock: Theoretical concepts and evolution in old-growth temperate forests, Central Europe

Cited by 16 publications

References 57 publications

Exploring the regolith with electrical resistivity tomography in large-scale surveys: electrode spacing-related issues and possibility

Exploring the regolith with electrical resistivity tomography in large-scale surveys: electrode spacing-related issues and possibility

Deep Nitrate Accumulation in a Highly Weathered Subtropical Critical Zone Depends on the Regolith Structure and Planting Year

Differentiated Neogene bauxitization of volcanic rocks (western Cameroon): Morpho-geological constraints on chemical erosion

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