Liquefaction Susceptibility of Soils With Clay Particles from Earthquake-induced Landslides

The main reason for earthquake-induced landslides is liquefaction of soil, a process considered to occur mostly in sandy soils. Liquefaction can occur in clayey soils has also been reported and proven in the recent literature, but liquefaction in clayey soils still remains unclear and there are many questions that need to be addressed. In order to address these questions, an depth study on the liquefaction potential of clayey soils was conducted on the basis of field investigation and a series of laboratory tests on the samples collected from the sliding surface of the landslides. The liquefaction potential of the soils was studied by means of undrained cyclic ring-shear tests. Research results show that the liquefaction potential of sandy soils is higher than that of clayey soils given the same void ratio; the soil resistance to liquefaction rises with an increase in plasticity for clayey soils; relation between plasticity index and the liquefaction potential of soil can be used in practical application to estimate the liquefaction potential of soil.     

Charge Properties and Clay Mineral Composition of Tianbao Mountains Soils

The clay mineral association,oxides of clay fraction and surface charge properties of 7 soils,which are developed from granite,located at different altitudesof the Tianbao Mountains were studied.Results indicate that with the increase in altitude,1) the weathering process and desilicification of soil clay minerals became weaker,whereas the leaching depotassication and the formation process of hydroxy-aluminum interlayer got stronger;2)the contents of amorphous and complex aluminum and iron,and the activity of aluminum and iron oxides for soil clay fraction increased;and 3) the amount of variable negarive charge,anion exchange capacity and the values of PZC and PZNC also increased.The activity of aluminum and iron oxides,the accumulation of aluminum,and surface charge characteristics and their relation to clay oxides of the vertical zone soils were observed and recorded.     

Clay Addition to Sandy Soil——Influence of Clay Type and Size on Nutrient Availability in Sandy Soils Amended with Residues Differing in C/N ratio

Addition of clay-rich subsoil to sandy soil results in heterogeneous soil with clay peds(2-mm) or finely ground( 2 mm) clay soil(FG), which may affect the nutrient availability. The aim of this study was to assess the effect of clay soil particle size(FG or peds)and properties on nutrient availability and organic C binding in sandy soil after addition of residues with low(young kikuyu grass,KG) or high(faba bean, FB) C/N ratio. Two clay soils with high and low smectite percentage, clay and exchangeable Fe and Al were added to a sandy soil at a rate of 20%(weight/weight) either as FG or peds. Over 45 d, available N and P as well as microbial biomass N and P concentrations and cumulative respiration were greater in soils with residues of KG than FB. For soils with KG residues,clay addition increased available N and initial microbial biomass C and N concentrations, but decreased cumulative respiration and P availability compared to sandy soil without clay. Differences in measured parameters between clay type and size were inconsistent and varied with time except the increase in total organic C in the 53 μm fraction during the experiment, which was greater for soils with FG than with peds. We concluded that the high exchangeable Fe and Al concentrations in the low-smectite clay soil can compensate a lower clay concentration and proportion of smectite with respect to binding of organic matter and nutrients.     

Clay mineralogy,chemical weathering and landscape evolution in Arctic–Alpine Sweden

The purpose of this research was to: (1) characterize the clay mineralogy of soils in and adjacent to Kärkevagge, a recently deglaciated valley in Arctic Sweden, (2) document chemical weathering in a periglacial environment and (3) use the mineralogy to help explain landscape evolution. Soil samples were analyzed from 11 sites that differ in elevation, parent material, drainage, slope and vegetation. Parent materials include residuum, alluvium, colluvium and glaciofluvial material derived from garnet–mica–schist, plus, in one locality, a till of granitic origin. X-ray diffraction (XRD) was used to characterize the clay-size fraction (<2 μm). Muscovite, chlorite and mixed-layered (ML) minerals are the predominant soil minerals identified. ML minerals indicate chemical weathering and also act as tracers used to identify source areas of soil parent materials. High concentrations of ML minerals in the soils on the alpine ridges flanking Kärkevagge indicate in situ chemical weathering. At lower elevations within the valley, their distribution indicates that the ridges contributed sediments early on in the evolution of the landscape, but more recently the source has shifted towards ML-poor supply areas from lower elevations. Soil chemistry also supports this model; the alpine soils are base-poor while the valley soils are base-rich. The higher abundance of ML minerals in the alpine zone indicates either a long period of weathering or a greater period of development. The latter explanation supports the hypothesis that the ridge crests were covered by cold-based ice during the last glaciation; remnants of which still survive at the highest elevations. Cold-based ice preserved a pre-weathered landscape that was the primary source of the ML minerals in the soils in the valley.     

Bio—Mobilization of Potassium from Clay Minerals：II.By ectmycorrhizal Fungi

Ectomycorrhizal ungi,including Cenococcum geophilum SIV( Cg SIV),and Pisolithus tinctorius 2144(Pt 2144),441(Pt 441) and XC1(Pt XC1),were cultured in Pachlewski liquid medium with H2KPO4,KCl-saturated vermiculite and mica as K sources,respectively,to investigate the mechanism of K absorption and mobilization by the fungi,FUngal growth rate,K absoprtion and mobilization varied significantly among the fungal species,Faster growth and greater K accumulation in Pt XC1 than Pt 2144,Pt 441 and Cg siv were observed.Ectomycorrhizal fungi depressed HCl-soluble K in minerals after successive extractions by water and NH4OAc.Ratio of the total amount of K,including water-,NH4OAc-and HCl-soluble K,lost from substrates to the K accumulated in fungal colonies was less than 60%.These reveal that the ectomycorrhizal fungi could utilize K in Interlayer and structural pools,which are usually unavailable for plants in short period.Large differences in the depletion of K in interlayer and structural pools by fungi were observed at fungal harvest.Taking into account the nutrient absorption by ectomycorrhizal fungi in symbionts and the direct contact between hyphae and soils,the fungi species colonized on the root surfaces seemed to be related to the effectiveness of mycorrhizas to utilize K in soils.Ectomycorrhizal fungi differed in the efflux of protons and oxalate.Pt XC1 was observed to have greatest ability to effuse protons and oxalate among the fungi adopted in the experiment.Furthermore,the higther the concentrations of protons and oxalate in the liquid culture solutions,the larger the depletion of K in interlayer and structural pools in minerals by fungi,Protons could replace interlayer K and chelation of oxalate with Fe and Al in crystal lattice could cause weathering of clay minerals.So,protons and oxalate produced by ectomycorrhizal fungi might play an important role in K mobilization in these two pools.     

Remediation of Perfluorooctane Sulfonate in Contaminated Soils by Modified Clay Adsorbent—a Risk-Based Approach

Perfluorooctane sulfonate (PFOS), which has numerous uses besides being an ingredient in the formulation of aqueous film-forming foams, is considered as an emerging pollutant of increasing public health and environmental concern due to recent reports of its worldwide distribution, environmental persistence and bioaccumulation potential. In an attempt to recommend a ‘risk-based’ remediation strategy, this study investigates the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent (MatCARE?, patent number 2009905953). Batch adsorption tests demonstrated a much faster adsorption kinetics (only 60 min to reach equilibrium) and remarkably higher PFOS adsorption capacity (0.09 mmol g^?1) of the MatCARE? compared to a commercial activated carbon (0.07 mmol g^?1). Treatability studies, performed by treating the PFOS-contaminated soils with the MatCARE? (10 % w/w) and then incubating at 25 and 37 °C temperatures maintaining 60 % of the maximum water holding capacity of the soils for a period of a year, demonstrated a negligible release (water extractable) of the contaminant (only 0.5 to 0.6 %). The fixation of PFOS in soils by the new adsorbent was exothermic in nature. Soils with higher clay and organic matter content, but lower pH values, retained PFOS to a much greater extent. A cost analyses confirmed that the MatCARE^TM could be an economically viable option for the ‘risk-based’ remediation of PFOS in contaminated waters and soils.     

Vermiculite-Type Clay Minerals in Some “Kuroboku” Soils Distributed in Mie Prefecture of West Japan

In the past several years, the occurrence of vermiculite-type clay minerals and the problem of the formation of Al-interlayers have attracted the intensive attention of soil clay mineralogists. A number of papers have appeared in Japan, in Which the identification data of the vermiculite-type minerals with stable 14 Å spacing were given. (Matsui 1959, 1960; Kanno 1961b, Kato 1961, 1962a, 1962b; Egawa 1963).     

Dark-Humus Residual–Hydromorphic Soils of the Slopes of the Northern Uvaly Formed on Clay Triassic Deposits

Northern Uvaly dark-humus soils and agrozems, which formed on Triassic clay deposits, are examined. Their hydromorphic nature is identified based on determination of their organic matter properties. Nonconformity of the hydromorphic features to the current moisture conditions is found, which indicates the residual character of hydromorphism and confirms the concept that the territory of the Uvaly was uplifted during the Holocene.     

Effects of Organic Anions on Phosphate Adsorption and Desorption from Variable—Charge Clay Minerals and Soil

Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite,goethite,amorphous Al-oxide and Ultisol were studied.P adsorption was significantly decreased as the concentration of the organic anions increased from 10^-5 to 10^-1 M.At 0.1 M and pH 7.0,tartrate decreased P adsorption by 27.6%-50.6% and citrate by 37.9-80.4%,depending on the kinds of adsorbent.Little Al and/or Fe were detected in the equilibrium solutions,even at the highest concentration of the organic anions.Effects of the organic anions on phosphate adsorption follow essentially the competitive adsorption mechanism.The selectivity coefficients for competitive adsorption can be used to compare the effectiveness of different organic anions in reducing P adsorption under given gonditions. Phosphate desorption was increased by 3 to 100 times in the presence of 0.001 M citrate or tartrate compared to that in 0.02 M KCl solution alone.However,for all the soil and clay minerals studied the amount of P desorbed by citrate or tartrate was generally lower than or close to that of isotopically exchangeable P.The effect of organic anions on phosphate desorption arises primarily from ligand exchange.     

Clay amendment to sandy soil—effect of clay concentration and ped size on nutrient dynamics after residue addition

Purpose

Crop growth on sandy soils can be increased by claying. In modified sandy soils, the added clay is in the form of peds ranging in size from millimetres to centimetres creating a highly non-uniform matrix where ped size could influence nutrient availability and organic C binding. The aim of the study was to determine the effect of clay addition rate and ped size in residue amended sandy soil on soil respiration, nutrient availability and organic C retention.

Materials and methods

In this study, clay peds of 1, 2 or 3 mm size derived from a clay-rich Vertosol (73 % clay) were added to a sandy soil (3 % clay) at clay addition rates of 10 and 20 % w/w. After the addition of ground faba bean residue (C/N 37) at 10 g kg^?1, the soils were incubated for 45 days at 80 % of water-holding capacity.

Results and discussion

Clay addition had no consistent effect on cumulative respiration, but reduced NH₄ ⁺ availability with a greater reduction at 20 % compared to 10 % clay and with 1 and 2 mm compared to 3 mm peds. Sandy soil with clay peds had a greater maximum NH₄ ⁺ and P sorption capacity than sandy soil alone, and sorption capacity was higher at 20 % compared to 10 % clay addition and greater with 1 mm compared to 3 mm peds. Retrieval of clay peds at the end of the experiment showed ped breakdown during the experiment but also the formation of larger peds. Compared to the <53 μm fraction added at the start of the experiment, the total organic carbon (TOC) content of the <53 μm fraction was increased up to nearly two fold, particularly in the smaller peds (1 and 2 mm).

Conclusions

When sandy soils are amended with clay, N availability and organic C binding depend on both clay addition rate and ped size.

     

The Effect of Treatment with Hydrogen Peroxide and the Mehra–Jackson Reagent on X-ray Diffraction Patterns of Clay Fractions

X-ray diffraction patterns of clay fractions from the AEL and EL horizons of pale-podzolic soil before and after treatment with 10% H₂O₂ and the Mehra–Jackson reagent in different sequences have been examined. The successive treatment with 10% H₂O₂ and then with the Mehra–Jackson reagent causes dissolution of Al-hydroxy-interlayers in pedogenic chlorites and the respective increase in the content of labile minerals because of a dramatic decrease in pH upon the treatment with hydrogen peroxide. The rate of these changes depends on the degree of chloritization of pedogenic chlorites in the initial samples. The result of the reverse sequence of the treatments of clay fractions (initially with the Mehra–Jackson reagent and then with hydrogen peroxide) is opposite: the chloritization of labile minerals becomes more intensive. It is provided by pH values that do not drop below 7.5 at any treatment stage. At particular stages, pH values favors the mobilization of Al compounds and their subsequent polymerization in the interlayer space of labile structures. We suppose that hydroxyl-aluminosilicate layers may be formed in the interlayer space upon this treatment sequence.     

Effect of Magnesium Chloride–Induced Salinity on Carbon Dioxide Evolution and Nitrogen Mineralization in a Silty Clay Loam Soil

A laboratory incubation experiment was conducted to evaluate the effect of magnesium chloride–induced salinity on carbon dioxide (CO₂) evolution and nitrogen (N) mineralization in a silty loam nonsaline alkaline soil. Magnesium chloride (MgCl₂) salinity was induced at 0, 4, 8, 12, 16, 20, 30, and 40.0 dS m^?1 and measured CO₂ evolution and N mineralization during 30 days of incubation. Both CO₂ evolution and N mineralization decreased significantly with increasing salinity. The cumulative CO₂ evolution decreased from 235 mg kg^?1 soil at electrical conductivity (EC) 0.65 dS m^?1 to 11.9 mg kg^?1 soil at 40 dS m^?1 during 30 days of incubation. Similarly, N mineralization decreased from 185.4 mg kg^?1 at EC 0.65 dS m^?1 to 34.45 mg kg^?1 at EC 40.0 dS m^?1 during the same period. These results suggested that increasing magnesium chloride salinity from 4 dS m^?1 adversely affect microbial activity in terms of carbon dioxide evolution and N mineralization.     

Clay,Organic Carbon,Available P and Calcium Carbonate Effects on Phosphorus Release and Sorption–Desorption Kinetics in Alluvial Soils

Information on phosphorus (P) release kinetics and sorption–desorption in soils is important for understanding how quickly reaction approaches equilibrium and replenishes the depleted soil solution. Laboratory experiments were conducted to study the P release and sorption–desorption kinetics in soils differing in clay, soil organic carbon (SOC), available P, and calcium carbonate (CaCO₃) contents. Phosphorus release from soils proceeded in two phases: initially faster phase followed by a slower phase as equilibration progressed. Elovich equation (R² ≥ 0.97**) described well the P release versus time data. P release coefficients for power function were significantly correlated with available P and SOC. Freundlich sorption constants increased with increase in clay and CaCO₃ content. With increase in SOC and available P concentration in soils, substantial reduction in sorption constants was observed. It was concluded that for efficient P management, it is important to take into account soil texture, the existing soil P level, SOC content, and soil calcareousness.     

Acid–Base Characteristics and Clay Mineralogy in the Rhizospheres of Norway Maple and Common Spruce and in the Bulk Mass of Podzolic Soil

Eurasian Soil Science - Acid–base characteristics and composition of clay minerals were estimated in the rhizospheres of Norway maple (Acer platanoides) and common spruce (Picea abies) and in...     

Clay Mineralogy of the Wadi M’Goun Sediments,Their Source,and Distribution on the Southern Flank of the Central High Atlas Mountains (Morocco)

Eurasian Soil Science - Clay minerals are regarded as the most critical chemical and weathering components in ground. To establish the origin and distribution of the clay mineral associations of...     

Mineral Composition of Clay Fractions and Oxygen Vacancies in Silt-Sized Quartz in Soils on the Ka-Etsu Plateau,Fukui, Central Japan—Possibility of Eolian Dust Brought from Northern Asia as Parent Material of Soils

Fine- to medium-textured soils are distributed on the Early Pliocene rocks and Pleistocene sandy sediments in the Ka-Etsu plateau. The Jingaoka (JIN) soil was classified into Aluandic Andosols by WRB, and Low-humic Non-allophanic Kuroboku soils by the Fourth Committee for Soil Classification and Nomenclature of the Japanese Society of Pedology, although it was similar morphologically to Yellow-Brown Forest soils. On the other hand, the Tomitsu (TMI) and Yamamuro (YAM) soils were classified into Hyperdystri-Chromic Cambisols by WRB, and Typic Yellow-Brown Forest soils by the Fourth Committee for Soil Classification and Nomenclature based on the morphological, physical and chemical properties. These soils were influenced considerably by the Akahoya tephra, especially the JIN soil. Based on the results of clay-mineralogical analysis and the measurement of the ESR-signal intensity associated with the oxygen vacancies in fine quartz, a large part of parent materials in the soils distributed on the Ka-Etsu plateau was derived from the eolian dust which was brought with the NW winter monsoon from the Precambrian sediments in the northern part of the Asian continent during MIS 2 (24–11 thousand years ago) at the Last Glacial Maximum. The parent materials of the fine-textured JIN soil located on the highest terrace near the rocky coastline were mostly composed of eolian dust, although the influenced of the Akahoya tephra was recognized. The parent materials of the TMI soil were admixed with a small amount of autochthonous materials from the sandy coast located windward. In the YAM soil which was located on the side of a hilly area distant from the coastline, the ESR-signal intensity in fine quartz was considerably low, and the admixture of autochthonous materials was also considered since the texture of this soil was coarser than that of the JIN and TMI soils.