Ecohydrologic processes and soil thickness feedbacks control limestone-weathering rates in a karst landscape

The national soil monitoring network (Nabo) consists of 105 sites across Switzerland, 28 of which are located in forests. After 25 years already seven forest sites (25%) were more or less damaged by storms. Two of them had to be abandoned for a decade to recover. Concerning precautionary soil protection the legal guide value is exceeded at three forest sites for cadmium and at one site also for chromium. These sites are all based on Jurassic limestone, and it is well known that residuals of limestone weathering can be rich in cadmium. Hence, the enrichment is supposed to be of geogenic origin. In the Canton Ticino the top soil at Novaggio site exceeds the guide value for lead. Here, anthropogenic origin is very likely. The analysis of the organic pollutants PAH and PCB in the third sampling campaign revealed moderate concentrations with a maximum lower than or equal to ⅔ of the corresponding guide value. Based on the results of the first four sampling campaigns it can be concluded that only small changes in the measured heavy metal concentrations in the top soils at the 28 Nabo sites were found. The most dynamic element is lead. Most of the concentrations are far below the guide values, the same holds for the organic pollutants PAH and PCB.

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Calcium Budgets for Catchments as Interpreted by Strontium Isotopes

Hydrology Research ◽

10.2166/nh.1989.0007 ◽

1989 ◽

Vol 20 (2) ◽

pp. 85-96 ◽

Cited By ~ 33

Author(s):

Gunnar Jacks ◽

Göran Åberg ◽

P. Joseph Hamilton

Keyword(s):

Steady State ◽

Forest Ecosystem ◽

Coniferous Forest ◽

Strontium Isotopes ◽

Runoff Water ◽

Weathering Rate ◽

Weathering Rates ◽

Exchangeable Calcium

Strontium isotopes in precipitation, soil and runoff water can be used to establish a ratio of wet plus dry deposited Sr to Sr released by weathering. This ratio is especially enhanced in areas with old acid Proterozoic rocks (0.6-2.5 Ga) and Archean rocks (>2.5 Ga). Since Sr and Ca behave in an analogous way in the coniferous forest ecosystem the results for Sr can be used for the determination of Ca. If the deposition of calcium can be calculated reasonably accurately the weathering rate can also be estimated. Five catchments have been investigated using this approach. Three of them seem to be close to a steady state, wherein the losses and gains of calcium to the system are equal. In the two southern-most catchments there seems to be an ongoing loss of exchangeable calcium. The loss by runoff occurs with sulphate being the dominant anion. Weathering rates of 1.5 to 4.8 kg Ca/ha year have been estimated.

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EVALUATING HUMAN-ENVIRONMENTAL IMPACTS TO THE KARST LANDSCAPE OF PHONG NHA-KE BANG NATIONAL PARK, VIETNAM USING A MODIFIED KARST DISTURBANCE INDEX METHODOLOGY

10.1130/abs/2016am-281312 ◽

2016 ◽

Author(s):

Leslie North ◽

◽

Vu Thi Minh Nguyet ◽

Jason Polk ◽

Tong Phuc Tuan ◽

...

Keyword(s):

Environmental Impacts ◽

National Park ◽

Disturbance Index ◽

Karst Landscape

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CARBON DIOXIDE DYNAMICS WITHIN THE CRITICAL ZONE OF A KARST LANDSCAPE: SAVOY EXPERIMENTAL WATERSHED, ARKANSAS

10.1130/abs/2017am-305389 ◽

2017 ◽

Author(s):

Sarah G. Williams ◽

◽

Joshua M. Blackstock ◽

Matthew D. Covington

Keyword(s):

Carbon Dioxide ◽

Critical Zone ◽

Karst Landscape

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SR- AND U-ISOTOPE STUDIES OF KARST LANDSCAPE EVOLUTION AT BUFFALO NATIONAL RIVER, NORTHERN ARKANSAS, USA

10.1130/abs/2018sc-310117 ◽

2018 ◽

Author(s):

James B. Paces ◽

◽

Mark R. Hudson ◽

Chuck Bitting ◽

Adam M. Hudson ◽

...

Keyword(s):

Landscape Evolution ◽

Karst Landscape ◽

Isotope Studies

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Development and Evaluation of Relative Relief Based Soil Thickness Model: A Comparative Study in Hilly Terrain, South Korea

KSCE Journal of Civil Engineering ◽

10.1007/s12205-021-1379-9 ◽

2021 ◽

Author(s):

Ananta Man Singh Pradhan ◽

Yun-Tae Kim

Keyword(s):

South Korea ◽

Comparative Study ◽

Hilly Terrain ◽

Soil Thickness ◽

Relative Relief

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An Improved Segmentation Method for Automatic Mapping of Cone Karst from Remote Sensing Data Based on DeepLab V3+ Model

Remote Sensing ◽

10.3390/rs13030441 ◽

2021 ◽

Vol 13 (3) ◽

pp. 441

Author(s):

Han Fu ◽

Bihong Fu ◽

Pilong Shi

Keyword(s):

Remote Sensing ◽

Remote Sensing Data ◽

Guizhou Province ◽

Training Dataset ◽

Optical Remote Sensing ◽

Remote Sensing Images ◽

Karst Landscape ◽

Heritage Site ◽

Training Samples ◽

Input Module

The South China Karst, a United Nations Educational, Scientific and Cultural Organization (UNESCO) natural heritage site, is one of the world’s most spectacular examples of humid tropical to subtropical karst landscapes. The Libo cone karst in the southern Guizhou Province is considered as the world reference site for these types of karst, forming a distinctive and beautiful landscape. Geomorphic information and spatial distribution of cone karst is essential for conservation and management for Libo heritage site. In this study, a deep learning (DL) method based on DeepLab V3+ network was proposed to document the cone karst landscape in Libo by multi-source data, including optical remote sensing images and digital elevation model (DEM) data. The training samples were generated by using Landsat remote sensing images and their combination with satellite derived DEM data. Each group of training dataset contains 898 samples. The input module of DeepLab V3+ network was improved to accept four-channel input data, i.e., combination of Landsat RGB images and DEM data. Our results suggest that the mean intersection over union (MIoU) using the four-channel data as training samples by a new DL-based pixel-level image segmentation approach is the highest, which can reach 95.5%. The proposed method can accomplish automatic extraction of cone karst landscape by self-learning of deep neural network, and therefore it can also provide a powerful and automatic tool for documenting other type of geological landscapes worldwide.

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Co-variation of silicate, carbonate and sulfide weathering drives CO2 release with erosion

Nature Geoscience ◽

10.1038/s41561-021-00714-3 ◽

2021 ◽

Vol 14 (4) ◽

pp. 211-216

Author(s):

Aaron Bufe ◽

Niels Hovius ◽

Robert Emberson ◽

Jeremy K. C. Rugenstein ◽

Albert Galy ◽

...

Keyword(s):

Erosion Rate ◽

Global Climate ◽

Stream Water ◽

Sulfide Oxidation ◽

Silicate Weathering ◽

Emission Rates ◽

Mountain Ranges ◽

Weathering Rates ◽

Southern Taiwan ◽

Co2 Release

AbstractGlobal climate is thought to be modulated by the supply of minerals to Earth’s surface. Whereas silicate weathering removes carbon dioxide (CO2) from the atmosphere, weathering of accessory carbonate and sulfide minerals is a geologically relevant source of CO2. Although these weathering pathways commonly operate side by side, we lack quantitative constraints on their co-variation across erosion rate gradients. Here we use stream-water chemistry across an erosion rate gradient of three orders of magnitude in shales and sandstones of southern Taiwan, and find that sulfide and carbonate weathering rates rise with increasing erosion, while silicate weathering rates remain steady. As a result, on timescales shorter than marine sulfide compensation (approximately 106–107 years), weathering in rapidly eroding terrain leads to net CO2 emission rates that are at least twice as fast as CO2 sequestration rates in slow-eroding terrain. We propose that these weathering reactions are linked and that sulfuric acid generated from sulfide oxidation boosts carbonate solubility, whereas silicate weathering kinetics remain unaffected, possibly due to efficient buffering of the pH. We expect that these patterns are broadly applicable to many Cenozoic mountain ranges that expose marine metasediments.

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A Modified Pressure–Sinkage Model for Studying the Effect of a Hard Layer in Sandy Loam Soil

Applied Sciences ◽

10.3390/app11125499 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5499

Author(s):

Nihal D. Salman ◽

György Pillinger ◽

Muammel M. Hanon ◽

Péter Kiss

Keyword(s):

Bearing Capacity ◽

Sandy Loam ◽

Sandy Loam Soil ◽

High Fidelity ◽

Load Bearing Capacity ◽

Soil Thickness ◽

Load Bearing ◽

Hard Layer ◽

Loam Soil ◽

New Perspective

The applicability of the typical pressure–sinkage models used to characterize the soil’s bearing properties is limited to homogeneous soils (infinite thickness) that have no hard layer. At a given depth, a hard layer can have a considerable impact on the soil’s load-bearing capacity. It is thus necessary to alter the pressure–sinkage equation by taking this condition into account when assessing the load-bearing capacity. The present paper aims to determine a simple, high-fidelity model, in terms of soil characterization, that can account for the hard layer affection. To assess hard layer affection in this paper, a plate sinkage test (bevameter) was conducted on sandy loam soil. To this end, the soil was prepared by considering three bulk densities and two soil thickness levels at 7–9% moisture content levels. According to the results, this paper put forth a new perspective and related equations for characterizing bearing performance. The sinkage modulus (k) is an intrinsic soil parameter that has a determined unit of N/cm2 and is significant for managing the bearing performance. The results showed that the new modulus sinkage model incorporates the main factor of the rigid layer effect involving high fidelity that the conventional models have failed to account for.

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