Liquid Contaminants Adhering to “Water-Dry” Soil Particles in the Unsaturated Zone

2020 ◽  
pp. 51-71
Author(s):  
Warren J. Lyman ◽  
Patrick J. Reidy ◽  
Benjamin Levy ◽  
Chi-Yuan Fan
Keyword(s):  
Unsaturated Zone ◽  
Soil Particles ◽  
Dry Soil

scholarly journals Mechanical Properties, Curing Mechanism, and Microscopic Experimental Study of Polypropylene Fiber Coordinated Fly Ash Modified Cement–Silty Soil

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5441
Author(s):  
Linfang Lu ◽  
Qiang Ma ◽  
Jing Hu ◽  
Qingfu Li
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Strain Curve ◽  
Soil Mass ◽  
Foundation Engineering ◽  
Soil Particles ◽  
Silty Soil ◽  
Curing Mechanism ◽  
Dry Soil ◽  
Modified Soil

Silty soil has the characteristics of low natural moisture content and poor viscosity, and the strength and deformation required for foundation engineering can be satisfied by reinforcing and improving the silt. In order to study the reinforcement and improvement effects of polypropylene (PP) fiber and fly ash (FA) on cement–silty soil, an unconfined compressive strength (UCS) test, scanning electron microscope (SEM) test, and X-ray diffraction (XRD) analysis test were carried out. Cement (mixed amounts are 4%, 8%, 12%, and 16% of dry soil mass) was used as the basic modifier, and PP fiber (mixed amounts are 0%, 0.15%, 0.3%, and 0.45% of dry soil mass) compounded with FA (adding amounts of 0%, 5%, 10%, and 15% of dry soil mass) were used as an external admixture of cement–silty soil to study the mechanical properties, curing mechanism, and microstructure of the modified soil in different ages of 7 d, 14 d, 28 d, and 60 d. The test results show that with the increase in cement and curing age, the UCS of the modified soil increases, and with the increase in the PP fiber and FA, the UCS of the modified soil first increases and then decreases; there is an optimal content of FA and PP fiber, which are 10 and 0.15%, respectively. A large amount of C-S-H and AFt substances are produced inside the modified soil to cover the surface of soil particles or fill in the pores between soil particles, forming a tight spatial network structure and improving the mechanical properties of the cement–soil. The intensity of the diffraction peaks of the mineral components within the modified soils is more influenced by the cement and age, and the effect of FA is weaker. The stress–strain curve of the modified soil is divided into elastic stage, plastic deformation stage, and strain-softening stage, and the specimens in each stage have corresponding deformation characteristics. By analyzing the behavioral characteristics and curing improvement mechanism of modified soil from the duo perspective of macro-mechanical properties and microstructural composition, it can provide some basis for the engineering application of silty soil.

Fungi of a Long Island oak–birch forest. III. Distribution and survival of ascospores in the A horizon

1984 ◽  
Vol 30 (3) ◽  
pp. 389-395 ◽  
Author(s):  
Lois Zlattner ◽  
S. E. Gochenaur
Keyword(s):  
Long Island ◽  
Sampling Period ◽  
Birch Forest ◽  
Measurable Effect ◽  
Soil Particles ◽  
Freeze Thaw ◽  
Coprophilous Fungus ◽  
Sordaria Fimicola ◽  
Dry Soil

A 1-year survey of soil ascomycetes in the A horizon of an oak–birch forest was conducted using the selective Warcup steaming technique. Fourteen species, including two sclerotial anamorphs, belonging to seven genera were isolated. Their propagules were rare and did not exceed an average of 300 per gram of dry soil, except in the fall when numbers increased fivefold. Only Coniochaeta nepalica and an unidentified Eupenicillium species were isolated at every sampling period. Survival of ascospores of C. nepalica and the coprophilous fungus Sordaria fimicola introduced into the A horizon was tested. Both the indigenous and foreign ascospores showed no loss of viability during 210 days of incubation in soil, but approximately 15% of the Sordaria spores were ruptured as soil particles shifted during freeze–thaw cycles. The latter had no measurable effect on the much smaller ascospores of Coniochaeta.

Cohesion in colloidal soils

1925 ◽  
Vol 15 (4) ◽  
pp. 420-433 ◽  
Author(s):  
F. Hardy
Keyword(s):  
Calcium Carbonate ◽  
Moisture Content ◽  
Aqueous Suspension ◽  
Reliable Measure ◽  
Soil Particles ◽  
Colloidal Matter ◽  
Constant Moisture Content ◽  
Dry Soil ◽  
Moisture Conditions ◽  
Film Tension

1. Experiments in which were measured the resistances to (a) transverse breaking, (b) crushing, and (c) parting under tensile pull of standard blocks of soil prepared in different ways and under particular moisture conditions are described and discussed.2. The soils examined comprised three highly colloidal siliceous soils containing amounts of calcium carbonate ranging from 7·2 to 0·2 percent., and two red lateritic soils.3. The most significant results were obtained by employing, in a special tenacity apparatus, granular test-blocks, prepared by moistening sieve-graded dry soil packed into rectangular moulds. The results thus obtained are believed to furnish a reliable measure of the cohesiveness of soil colloidal matter, especially in soil blocks that have previously been brought to constant moisture content in a humidifier. The method of preparation simulates the effect of rain in causing the “running together” of colloidal soil particles.4. The relative cohesiveness of the soils examined appears to follow the same order as their rates of settling from aqueous suspension. This observation strengthens the view that cohesiveness in colloidal soils is to a certain extent due to chemical forces that depend on the presence of active atoms or atomic groups possessing powerful fields of residual affinity, although probably film tension also plays a part.

scholarly journals A Theoretical Investigation of the Critical Timescales Needed for Digging in Dry Soil Using a Biomimetic Burrowing Robot

2015 ◽  
Author(s):  
Monica Isava ◽  
Amos G. Winter
Keyword(s):  
Theoretical Model ◽  
Stress State ◽  
Theoretical Investigation ◽  
Sensor Placement ◽  
Contraction Time ◽  
Soil Particles ◽  
Potential Applications ◽  
Dry Soil

RoboClam is a bio-inspired robot that digs into underwater soil efficiently by expanding and contracting its valves to fluidize the substrate around it, thus reducing drag. This technology has potential applications in fields such as anchoring, sensor placement, and cable installation. Though there are similar potential applications in dry soil, the lack of water to advect the soil particles prevents fluidization from occurring. However, theoretically, if the RoboClam contracts quickly enough, it will achieve a zero-stress state that will allow it to dig into dry soil with very little drag, independent of depth. This paper presents a theoretical model of the two modes of soil collapse to determine how quickly a device would need to contract to achieve this zero-stress state. It was found that a contraction time of 0.02 seconds would suffice for most soils, which is an achievable timescale for a RoboClam-like device.

Conception of vadose zone research in the area of Goczałkowice reservoir.

2013 ◽  
Vol 2 (1) ◽  
pp. 22-26
Author(s):  
Joanna Czekaj ◽  
Kamil Trepka
Keyword(s):  
Vadose Zone ◽  
Unsaturated Zone ◽  
Vertical Profile ◽  
Structural Model ◽  
Historical Data ◽  
Integrated System ◽  
Nitrate Transport ◽  
Strategic Research ◽  
Research Site ◽  
Observation Wells

Abstract Goczałkowice reservoir is one of the main source of drinking water for Upper Silesia Region. In reference to Water Frame Directive matter since 2010 the strategic research project: „Integrated system supporting management and protection of dammed reservoir (ZiZoZap)”, which is being conducted on Goczałkowice reservoir, has been pursued. In the framework of this project complex groundwater monitoring is carried on. One aspect is vadose zone research, conducted to obtain information about changes in chemical composition of infiltrating water and mass transport within this zone. Based on historical data and the structural model of direct catchment of Goczałkowice reservoir location of the vadose zone research site was selected. At the end of November 2012 specially designed lysimeter was installed with 10 MacroRhizon samplers at each lithological variation in unsaturated zone. This lysimeter, together with nested observation wells, located in the direct proximity, create the vadose zone research site which main aim is specifying the amount of nitrate transport in the vertical profile.

DYNAMICS OF BARLEY FLAVONOID AND PRODUCTIVITY UNDER UF-A RADIATION

1970 ◽  
pp. 14-18
Author(s):  
L. I. Goncharova ◽  
P. N. Tsygvintsev ◽  
О. А. Guseva
Keyword(s):  
Grain Yield ◽  
Defense Mechanisms ◽  
Antioxidant Defense ◽  
Malonic Dialdehyde ◽  
Growth Period ◽  
Negative Effects ◽  
Uv Spectrum ◽  
Quantum Energy ◽  
Dry Soil ◽  
Universal Mechanism

The effect of increased UV-A radiation during the ontogeny of barley plants of the Vladimir variety in the vegetation experiment was studied. Changes in the content of malonic dialdehyde, flavonoids and grain yield were revealed. UV-A radiation as compared to UV-B radiation, has lower quantum energy and can have both positive and negative effects on plant regulatory and photosynthetic processes. One of the most damaging effects of increased levels of UV-A radiation is oxidative stress, which causes lipid peroxidation of biological membranes. The existence of a plant cell in such conditions is possible only thanks to a system of antioxidant defense mechanisms. The accumulation of phenolic compounds under the action of UV radiation is a universal mechanism of protection against photodamage, which was formed in the early stages of the evolution of photoautotrophic organisms. Flavonoids are localized in the epidermis of plant tissues and act as an internal filter. The content of flavonoids is determined by the genotype and due to ontogenetic patterns. Plants were grown in a greenhouse, in vessels containing 4.5 kg of air-dry soil. The repetition is threefold (3 vessels in each variant). Sowing density - 13 plants in each vessel. As a source of UV-A radiation used lamps Black Light BLUE company Philips. Plants were irradiated for 5 hours a day from 10 to 15 hours at 13, 25, 34, 43 and 52 stages of organogenesis. The magnitude of the daily biologically effective dose of UV-A radiation was 60.7 kJ / m2. The solar part of the UV spectrum in the vegetation experiment was absent in the greenhouse. The nature of changes in the content of flavonoids under the action of UV-A irradiation during the growing season of plants with the dynamics of the oxidative process has been established. The first maximum was observed during the vegetative growth period, the second - at the earing stage. The data obtained indicate that flavonoids have ontogenetic conditionality and perform photoprotective functions. The increase in their content under the action of UV-A radiation is accompanied by an increase in resistance to photodamage, which is confirmed by the formation of grain yield.

Unsaturated zone characteristics rating for North Carolina

2001 ◽  
Author(s):  
Silvia Terziotti ◽  
Jo Leslie Eimers
Keyword(s):  
North Carolina ◽  
Unsaturated Zone
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