Luvisolic soils of Canada: Genesis, distribution, and classification

2011 ◽  
Vol 91 (5) ◽  
pp. 781-806 ◽  
Author(s):  
L. M. Lavkulich ◽  
J. M. Arocena
Keyword(s):  
Chemical Weathering ◽  
Ecosystem Functions ◽  
Soil Productivity ◽  
Exchange Reactions ◽  
Forming Process ◽  
Humid Climate ◽  
Forestry Practices ◽  
Air Movement ◽  
The Common ◽  
Bt Horizon

Lavkulich, L. M. and Arocena, J. M. 2011. Luvisols of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 781–806. Luvisols link the soil continuum on the Quaternary landscapes. These soils are developed from parent materials rich in Ca and Mg in a relatively humid climate. An acidic eluvial horizon overlying a phyllosilicate-enriched illuvial Bt horizon is the common horizon sequence in Luvisolic soils. Lessivage or the translocation of clays with minimal chemical alteration is the characteristic soil-forming process and results to the diagnostic Bt horizon with well-developed, oriented clay skins or cutans. These soils commonly form intergrades with Chernozems, Podzols and Vertisols. With time, the eluvial horizons experience increased chemical weathering and further release of sequioxides to form Brunisolic and Podzolic sequences within the eluvial Ae in biseqeual soils. Lessivage significantly influences several ecosystem functions of soils. The high amounts of phyllosilicates in the Bt horizon serve as one of the most active sorption sites in soils for metals and organic materials including soil carbon. Sorption of cations takes place through cation exchange reactions and determines the availability of cations to plant roots as well as in the “colloid facilitated transport” of strongly sorbing metals and organic pollutants. Clays in Bt can be restrictive to water and air movement as well as to root growth and distribution. Agricultural and forestry practices such as tillage can compact the structure of Luvisols and may decrease soil productivity.

Vipera berus (Linnaeus, 1758) remains from the Late Pleistocene of Slovakia

2017 ◽  
Vol 38 (2) ◽  
pp. 133-144 ◽  
Author(s):  
Martin Ivanov ◽  
Andrej Čerňanský
Keyword(s):  
Late Pleistocene ◽  
Mixed Forest ◽  
Axial Skeleton ◽  
Species Group ◽  
Climatic Conditions ◽  
Mammalian Fauna ◽  
Humid Climate ◽  
Vipera Berus ◽  
Faunal Assemblages ◽  
The Common

Completely preserved specimens of fossil snakes are extremely rare and ophidian palaeontologists are usually dependent only on disarticulated elements of a postcranial skeleton. Here we present an unusually well-preserved specimen of a small viperid snake from the Late Pleistocene firm travertine at the famous Gánovce-Hrádok Neanderthal mound in Slovakia. The complex study of both cranial and axial skeleton with well-preserved maxilla and basiparasphenoid confirms the presence of a viper from theVipera berusspecies group, and recent distribution ofV. berusspecies complex members supports identification of these preserved remains as belonging to the common adder,V. berus(Linnaeus, 1758). Associated faunal assemblages of the MFG-C and D mammalian fauna groups reported from the firm travertine indicate a humid climate in a predominantly woodland environment with typical forest species in the Gánovce-Hrádok vicinity throughout the Eemian optimum, and mixed forest and steppe environments in the late Eemian to early Weichselian stages. Occurrence ofV. berusdocuments the presence of open or semi-open biotopes with low vegetation. AlthoughV. berusoccurs in the Quaternary glacial/interglacial cycle and throughout the entire warm part, it never dominated herpetofaunal assemblages during the climatic optimum. Therefore, the presence ofV. berusmost likely indicates late Eemian or early Weichselian (interstadial) climatic conditions.

Researches on Control and Application of Wrinkles in the Thin-Walled Metal Plastic Forming Process

2013 ◽  
Vol 446-447 ◽  
pp. 1193-1196
Author(s):  
Zhu Lin Hu ◽  
Lian Fa Yang ◽  
Yu Lin He
Keyword(s):  
Metal Forming ◽  
Thin Metal ◽  
Forming Process ◽  
Forming Technology ◽  
Plastic Forming ◽  
The Common ◽  
Thin Walled

The thin metal plastic forming is an indispensable metal forming technology. Wrinkling is one of the common defects in plastic forming. If this kind of defects can be used properly, the formability of metal will be better. In this paper, the recent researches on the methods of identifying wrinkles, distinction of the useful wrinkles and harmful wrinkles, control and application of the wrinkles are summarized. The useful wrinkles are expected to improve the forming property.

scholarly journals Changes in the profile properties and chemical weathering characteristics of cultivated soils affected by anthropic activities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiangwen Li ◽  
Jing Du ◽  
Shouqin Zhong ◽  
En Ci ◽  
Chaofu Wei
Keyword(s):  
Chemical Weathering ◽  
Chemical Properties ◽  
Natural Evolution ◽  
Soil Taxonomy ◽  
Forming Process ◽  
Genetic Characteristics ◽  
Reference Base ◽  
Pedogenic Process ◽  
Diagnostic Characteristics ◽  
The Future

AbstractThe study of the pedogenic process in response to natural evolution, gradual anthropogenic shifts and engineering upheavals is of great significance for understanding, utilizing and transforming nature in the future. Although scholars have considered anthropic activities to be an important factor affecting pedogenesis, research on how and how much anthropic activities influence the soil-forming process is scant. This paper was conducted to analyse pedogenic characteristics dominated by anthropic activities. In this study, the parent materials and soils undergoing natural evolution (NE), tillage perturbation (TP) and engineering perturbation (EP) were selected as research objects. The genetic characteristics of soils undergoing NE, TP and EP are investigated mainly from three aspects: soil profile macromorphological characteristics, soil physical and chemical properties and chemical weathering characteristics. The results indicated that the influence of anthropic activities (TP and EP) on the process of pedogenesis is complicated. First, compared with NE, TP decreases the thickness of topsoil from 22.2 to 21.2 cm, while EP increases the thickness of topsoil from 22.2 to 23.2 cm, and EP causes the soil to have a high profile development index. Second, compared with TP, EP can improve bulk density (BD), soil organic carbon (SOC), total nitrogen (TN) and cation exchange capacity (CEC), Finally, the chemical weathering intensity differed among NE, TP and EP and followed the order of TP > NE > EP. Therefore, in the future, the genetic characteristics of soils dominated by anthropic activities should be considered. This will help us systematically understand the genesis and evolutionary characteristics of soil and lay a foundation for further perfecting the diagnostic horizon and diagnostic characteristics of the Soil Taxonomy and World Reference Base.

New Joining Concepts for Self-Pierce Riveting

2021 ◽  
Vol 883 ◽  
pp. 119-126
Author(s):  
Luis M. Alves ◽  
Rafael M. Afonso ◽  
Paulo A.F. Martins
Keyword(s):  
Lap Joints ◽  
Common Element ◽  
Tube Sheet ◽  
Structural Elements ◽  
Forming Process ◽  
Steel Tubes ◽  
Aluminum Sheets ◽  
Different Types ◽  
Deformation Mechanics ◽  
The Common

This paper is focused on innovative self-pierce riveting concepts to produce invisible joints in sheet-sheet and tube-sheet connections. The common element to these two different types of joints is the use of tubular rivets with chamfered ends, which are accessories in the case of sheet-sheet joints and constitutive (structural) elements in the case of tube-sheet joints. The presentation draws from the deformation mechanics of double-sided self-pierce riveting for producing lap joints in overlapped sheets to the development of self-pierce riveting of tubes to sheets, which is a new joining by forming process capable of attaching a sheet to the end of a tube, at room temperature. Aluminum sheets, carbon and stainless-steel tubes are utilized to demonstrate the effectiveness of the new self-pierce riveting concepts and finite element modelling using an in-house computer program gives support to the overall presentation. Destructive tests are carried out to evaluate the destructive strength that the joints are capable to withstand without failure.

Effect of forming process on mechanical and interfacial properties for thermoplastic composite I-stiffened structures

2021 ◽  
pp. 095400832110515
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Bonding Strength ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Forming Process ◽  
Molding Process ◽  
Influencing Mechanism ◽  
Stiffened Structures ◽  
The Common ◽  
Polymer Aging

The forming process is the core factor to control the quality of thermoplastic composite components. In this paper, the common I-stiffened structures in the aerospace field were taken as the research object, and the forming process scheme was designed. Based on the prefabrication of C-shaped parts, the I-stiffened structures were prepared by the compression molding process. The influence law of molding temperature on the quality of the prefabricated C-shaped parts was explored. The time dependence of the PEEK melt viscosity was tested to provide the basis for the optimization of forming process parameters of I-stiffened structures. The influencing mechanism of thermoplastic composites repeatedly forming to the bonding strength of remelting interface was studied. The results show that repeated forming would lead to polymer aging and result in low bonding strength at the remelting interface of the I-stiffened structures. Optimizing the forming process could effectively reduce the aging of materials and improve the bonding strength of the remelting interface and overall mechanical properties of components. The research provides technical guidance for the manufacturing of complex thermoplastic composite components, especially the influence mechanism of the forming process on the bonding strength of remelting interface.

Climate and soil type effects on crop residue decomposition

2020 ◽  
Author(s):  
Ed Gregorich ◽  
Mike Beare ◽  
Denis Curtin ◽  
Henry Janzen ◽  
Ben Ellert ◽  
...  
Keyword(s):  
Soil Type ◽  
Crop Residue ◽  
Crop Residues ◽  
Thermal Time ◽  
Barley Straw ◽  
Ecosystem Functions ◽  
Mean Annual Precipitation ◽  
Soil Productivity ◽  
Organic Matter Quality ◽  
Crop Residue Decomposition

<p>Crop residues are an important resource for maintaining soil productivity. The decay of crop residues is linked to many ecosystem functions, affecting atmospheric CO<sub>2</sub>, nutrient release, microbial diversity, and soil organic matter quality. The rate of decay, in turn, is regulated by soil type, management, and environmental variables, some of which will be changing in the future. Our objective in this study was to evaluate effects of soil type, climate, residue placement on the decomposition and retention of residue-derived C. <sup>13</sup>C-labelled barley straw was either placed at the surface or mixed to 10 cm in soils at four sites in Canada and one site in New Zealand representing different soil types and climates. Soils were collected periodically over 10 yr to determine <sup>13</sup>C remaining. The loss of C from crop residues occurred quickly, most (70-75%) within the first 2 yrs but with only 5-10% remaining after 10 yrs. There were large losses of C from the mixed treatments within the first year, with 20-50% lost after 6 months over winter and 50-70 % lost after one year; after that decomposition slowed. Temperature was the single most important factor regulating the rate of residue decay. Thermal time, expressed as cumulative degree days, explained more of the variability in residue C recovered than time (in calendar years). Slower decay of surface-placed residues may be attributed to lower mean annual precipitation at those sites. Thermal time is a robust, consistent way of predicting crop residue decay rates (or C storage) for comparing C kinetics across sites with different soils and climates.</p>

Intensive biomass removals and site productivity in Canada: A review of relevant issues

2010 ◽  
Vol 86 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Evelyne Thiffault ◽  
David Paré ◽  
Suzanne Brais ◽  
Brian D. Titus
Keyword(s):  
Forest Biomass ◽  
Field Trials ◽  
Forest Harvesting ◽  
Process Models ◽  
Ecosystem Functions ◽  
Soil Productivity ◽  
Site Productivity ◽  
Biomass Removal ◽  
The World ◽  
The Impact

A renewed interest in the intensive harvesting of forest biomass as a source of bioenergy in North America raises concerns about the impacts that this practice may have on the maintenance of forest soil productivity. In Canada, such concerns were first voiced in the 1970s, and studies were launched to investigate and predict the impact of intensive forest biomass removal on site productivity. Most of these studies focused on static nutrient budgets. In Canada and around the world, more detailed process models were also developed to study carbon, nitrogen and base cation cycles under different forest harvesting intensities. However, the validity of modelling results is still constrained by our lack of knowledge on the capacity of ecosystems to supply nutrients. A few sets of field trials have been established in Canada to gather empirical data on the impact of biomass removal on soil nutrient reserves as well as on tree nutrition and growth. Although still fairly recent, these field trials, along with the older ones established in other countries with similar site conditions and climates, provide opportunities to refine our understanding of the resilience of ecosystem processes and of the impacts of intensive biomass removal on ecosystem functions. Although numerous knowledge gaps and questions remain, some jurisdictions around the world have nevertheless issued policy directives and developed guidelines for biomass harvesting. As described by the concept of adaptive forest management, ecological monitoring of harvesting operations, scientific field testing and modelling can all interact to produce better knowledge that could then help improve policy directives. Key words: bioenergy, biomass, intensive harvesting, environmental sustainability

scholarly journals Chemical weathering and carbon dioxide consumption in a small tropical river catchment, southwestern India

2021 ◽  
Author(s):  
Baby Krishnan Nisha ◽  
Keshava Balakrishna ◽  
Harikripa Narayana Udayashankar ◽  
Busnur Rachotappa Manjunatha
Keyword(s):  
Carbon Dioxide ◽  
Western Ghats ◽  
Chemical Weathering ◽  
Small Rivers ◽  
Humid Climate ◽  
Tropical River ◽  
River Catchment ◽  
River Catchments ◽  
The Western Ghats ◽  
Southwestern India

AbstractStudies done on small tropical west-flowing river catchments located in the Western Ghats in southwestern India have suggested very intense chemical weathering rates and associated CO2 consumption. Very less studies are reported from these catchments notwithstanding their importance as potential sinks of atmospheric CO2 at the global scale. A total of 156 samples were collected from a small river catchment in the southwestern India, the Payaswini–Chandragiri river Basin, during pre-monsoon, monsoon and post-monsoon seasons in 2016 and 2017, respectively. This river system comprises two small rivers originating at an elevation of 1350 m in the Western Ghats in peninsular India. The catchment area is dominated by biotite sillimanite gneiss. Sodium is the dominant cation, contributing ~ 50% of the total cations, whereas HCO3− contributes ~ 75% of total anions. The average anion concentration in the samples varied in the range HCO3− > Cl− > SO42− > NO3− > F−, whereas major cation concentration varied in the range Na+  > Ca2+  > Mg2+  > K+. The average silicate weathering rate (SWR) was 42 t km−2 y−1 in the year 2016 and 36 t km−2 y−1 in 2017. The average annual carbon dioxide consumption rate (CCR) due to silicate rock weathering was 9.6 × 105 mol km−2y−1 and 8.3 × 105 mol km−2 y−1 for 2016 and 2017, respectively. The CCR in the study area is higher than other large tropical river catchments like Amazon, Congo-Zaire, Orinoco, Parana and Indus because of its unique topography, hot and humid climate and intense rainfall.

Clay mineral assemblages as palaeoclimatic indicators in a shallowing carbonate lacustrine system: Oligocene- Miocene, central Ebro Basin (NE Spain)

Clay Minerals ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 355-370
Author(s):  
M. J. Mayayo ◽  
A. Yuste ◽  
A. Luzόn ◽  
B. Bauluz
Keyword(s):  
Clay Mineral ◽  
Association Analysis ◽  
Chemical Weathering ◽  
Clay Mineralogy ◽  
Source Area ◽  
Ebro Basin ◽  
Humid Climate ◽  
Sem And Tem ◽  
Mineral Assemblages ◽  
Ne Spain

AbstractThis paper focuses on the clay mineralogy (using XRD, SEM and TEM methods) of the lacustrine “Calizas de Torrente de Cinca” unit that represents the Oligocene-Miocene transition in the central part of the Ebro Basin (NE Spain). Phyllosilicates are mainly detrital although Mgsmectites could have been generated in the lake.Although a temperate, relatively humid climate dominated the source area during the Oligocene-Miocene transition (Chattian-Aquitanian), as deduced by detrital phyllosilicates assemblage, mineralogical vertical trends along with sedimentological studies indicate some changes.Relatively warmer and more humid conditions during the late Chattian, that favoured increasing chemical weathering, were replaced during the early Aquitanian by drier conditions coinciding with the Mi-1 glaciation effects; this change is coeval with a transition from deeper to shallower lacustrine facies.Phyllosilicate association analysis has also permitted an improvement in the palaeogeographical sketch and infers that the Pyrenees are the main source area for the lacustrine system.

Mineralogy and geochemistry of the Ossa lake Complex sediments, Southern Cameroon: implications for paleoweathering and provenance

2021 ◽  
Vol 14 (4) ◽  
Author(s):  
Armel Zacharie Ekoa Bessa ◽  
Paul-Désiré Ndjigui ◽  
Gentry Calistus Fuh ◽  
John S. Armstrong-Altrin ◽  
Thierry Bineli Betsi
Keyword(s):  
Lake Sediments ◽  
Chemical Weathering ◽  
Source Area ◽  
Compositional Variation ◽  
Climatic Index ◽  
Humid Climate ◽  
Elemental Ratios ◽  
Margin Setting ◽  
Chemical Index ◽  
High Maturity

AbstractThis study investigates the provenance, paleoweathering, and paleoclimate of the Ossa lake sediments, based on the mineralogy and geochemistry data. Ossa lake sediments are characterized by silt and clay with high content of total organic carbon (TOC). Clay minerals are identified as kaolinite and illite types. Other dominant minerals identified are quartz, zircon, rutile, goethite, gibbsite, feldspar, and accessory vivianite. The major, trace, and rare earth element concentrations indicate that the sediments were derived from felsic rocks, such as gneisses and granitoids. The tectonic discrimination diagrams revealed an active margin setting. Weathering indices such as the chemical index of alteration (CIA), the plagioclase index of alteration (PIA), and chemical index of weathering (CIW) suggest intense chemical weathering in the source area. K2O/Na2O ratio and index of compositional variation (ICV) are consistent with high maturity of the sediments. The mineral assemblages and trace elemental ratios and climatic index “C” of the Ossa Lake sediments suggest a warm to semi-humid climate and deposition in an oxic shallow environment.

Sign in / Sign up

Export Citation Format

Share Document